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[Maria-developers] Progress (by Alexi): Store in binlog text of statements that caused RBR events (47)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Store in binlog text of statements that caused RBR events CREATION DATE..: Sat, 15 Aug 2009, 23:48 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Knielsen, Serg CATEGORY.......: Server-Sprint TASK ID........: 47 (http://askmonty.org/worklog/?tid=47) VERSION........: Server-9.x STATUS.........: Code-Review PRIORITY.......: 60 WORKED HOURS...: 72 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 35 PROGRESS NOTES: -=-=(Alexi - Thu, 24 Jun 2010, 09:49)=-=- Final implementation cleanup, testing, help Percona with build issues related to the WL Worked 5 hours and estimate 0 hours remain (original estimate increased by 5 hours). -=-=(Alexi - Thu, 24 Jun 2010, 09:47)=-=- Making rpl- and binlog-tests stable w.r.t. adding new binlog events. Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Knielsen - Mon, 21 Jun 2010, 08:32)=-=- Final review. Assist with some problems applying the patch. Worked 1 hour and estimate 0 hours remain (original estimate increased by 1 hour). -=-=(Guest - Thu, 17 Jun 2010, 00:38)=-=- Dependency deleted: 39 no longer depends on 47 -=-=(Knielsen - Mon, 07 Jun 2010, 07:13)=-=- Help debug some test failures seen in Buildbot. Worked 6 hours and estimate 0 hours remain (original estimate increased by 6 hours). -=-=(Knielsen - Mon, 31 May 2010, 06:49)=-=- Help Alexi debug+fix some test problems in the patch. Worked 4 hours and estimate 0 hours remain (original estimate unchanged). -=-=(Knielsen - Tue, 25 May 2010, 08:29)=-=- Help debug strange problem in mysqlbinlog.test. Worked 1 hour and estimate 4 hours remain (original estimate unchanged). -=-=(Knielsen - Mon, 17 May 2010, 08:45)=-=- Merge with latest trunk and run Buildbot tests. Worked 1 hour and estimate 5 hours remain (original estimate unchanged). -=-=(Knielsen - Wed, 05 May 2010, 13:53)=-=- Review of fixes to first review done. No new issues found. Worked 2 hours and estimate 6 hours remain (original estimate unchanged). -=-=(Knielsen - Fri, 23 Apr 2010, 12:51)=-=- Status updated. --- /tmp/wklog.47.old.28747 2010-04-23 12:51:36.000000000 +0000 +++ /tmp/wklog.47.new.28747 2010-04-23 12:51:36.000000000 +0000 @@ -1 +1 @@ -In-Progress +Code-Review ------------------------------------------------------------ -=-=(View All Progress Notes, 37 total)=-=- http://askmonty.org/worklog/index.pl?tid=47&nolimit=1 DESCRIPTION: Store in binlog (and show in mysqlbinlog output) texts of statements that caused RBR events This is needed for (list from Monty): - Easier to understand why updates happened - Would make it easier to find out where in application things went wrong (as you can search for exact strings) - Allow one to filter things based on comments in the statement. The cost of this can be that the binlog will be approximately 2x in size (especially insert of big blob's would be a bit painful), so this should be an optional feature. HIGH-LEVEL SPECIFICATION: Content ~~~~~~~ 1. Annotate_rows_log_event 2. Server option: --binlog-annotate-rows-events 3. Server option: --replicate-annotate-rows-events 4. mysqlbinlog option: --print-annotate-rows-events 5. mysqlbinlog output 1. Annotate_rows_log_event [ ANNOTATE_ROWS_EVENT ] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Describes the query which caused the corresponding rows events. Has empty post-header and contains the query text in its data part. Example: ************************ ANNOTATE_ROWS_EVENT ************************ 00000220 | B6 A0 2C 4B | time_when = 1261215926 00000224 | 33 | event_type = 51 00000225 | 64 00 00 00 | server_id = 100 00000229 | 36 00 00 00 | event_len = 54 0000022D | 56 02 00 00 | log_pos = 00000256 00000231 | 00 00 | flags = <none> ------------------------ 00000233 | 49 4E 53 45 | query = "INSERT INTO t1 VALUES (1), (2), (3)" 00000237 | 52 54 20 49 | 0000023B | 4E 54 4F 20 | 0000023F | 74 31 20 56 | 00000243 | 41 4C 55 45 | 00000247 | 53 20 28 31 | 0000024B | 29 2C 20 28 | 0000024F | 32 29 2C 20 | 00000253 | 28 33 29 | ************************ In binary log, Annotate_rows event follows the (possible) 'BEGIN' Query event and precedes the first of Table map events which accompany the corresponding rows events. (See example in the "mysqlbinlog output" section below.) 2. Server option: --binlog-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the master to write Annotate_rows events to the binary log. * Variable Name: binlog_annotate_rows_events * Scope: Global & Session * Access Type: Dynamic * Data Type: bool * Default Value: OFF NOTE. Session values allows to annotate only some selected statements: ... SET SESSION binlog_annotate_rows_events=ON; ... statements to be annotated ... SET SESSION binlog_annotate_rows_events=OFF; ... statements not to be annotated ... 3. Server option: --replicate-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the slave to reproduce Annotate_rows events recieved from the master in its own binary log (sensible only in pair with log-slave-updates option). * Variable Name: replicate_annotate_rows_events * Scope: Global * Access Type: Read only * Data Type: bool * Default Value: OFF NOTE. Why do we additionally need this 'replicate' option? Why not to make the slave to reproduce this events when its binlog-annotate-rows-events global value is ON? Well, because, for example, we may want to configure the slave which should reproduce Annotate_rows events but has global binlog-annotate-rows-events = OFF meaning this to be the default value for the client threads (see also "How slave treats replicate-annotate-rows-events option" in LLD part). 4. mysqlbinlog option: --print-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ With this option, mysqlbinlog prints the content of Annotate_rows events (if the binary log does contain them). Without this option (i.e. by default), mysqlbinlog skips Annotate_rows events. 5. mysqlbinlog output ~~~~~~~~~~~~~~~~~~~~~ With --print-annotate-rows-events, mysqlbinlog outputs Annotate_rows events in a form like this: ... # at 1646 #091219 12:45:26 server id 100 end_log_pos 1714 Query thread_id=1 exec_time=0 error_code=0 SET TIMESTAMP=1261215926/*!*/; BEGIN /*!*/; # at 1714 # at 1812 # at 1853 # at 1894 # at 1938 #091219 12:45:26 server id 100 end_log_pos 1812 Query: `DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.a=t2.a AND t2.a=t3.a` #091219 12:45:26 server id 100 end_log_pos 1853 Table_map: `test`.`t1` mapped to number 16 #091219 12:45:26 server id 100 end_log_pos 1894 Table_map: `test`.`t2` mapped to number 17 #091219 12:45:26 server id 100 end_log_pos 1938 Delete_rows: table id 16 #091219 12:45:26 server id 100 end_log_pos 1982 Delete_rows: table id 17 flags: STMT_END_F ... LOW-LEVEL DESIGN: Content ~~~~~~~ 1. Annotate_rows event number 2. Outline of Annotate_rows event behavior 3. How Master writes Annotate_rows events to the binary log 4. How slave treats replicate-annotate-rows-events option 5. How slave IO thread requests Annotate_rows events 6. How master executes the request 7. How slave SQL thread processes Annotate_rows events 8. General remarks 1. Annotate_rows event number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To avoid possible event numbers conflict with MySQL/Sun, we leave a gap between the last MySQL event number and the Annotate_rows event number: enum Log_event_type { ... INCIDENT_EVENT= 26, // New MySQL event numbers are to be added here MYSQL_EVENTS_END, MARIA_EVENTS_BEGIN= 51, // New Maria event numbers start from here ANNOTATE_ROWS_EVENT= 51, ENUM_END_EVENT }; together with the corresponding extension of 'post_header_len' array in the Format description event. (This extension does not affect the compatibility of the binary log). Here is how Format description event looks like with this extension: ************************ FORMAT_DESCRIPTION_EVENT ************************ 00000004 | A1 A0 2C 4B | time_when = 1261215905 00000008 | 0F | event_type = 15 00000009 | 64 00 00 00 | server_id = 100 0000000D | 7F 00 00 00 | event_len = 127 00000011 | 83 00 00 00 | log_pos = 00000083 00000015 | 01 00 | flags = LOG_EVENT_BINLOG_IN_USE_F ------------------------ 00000017 | 04 00 | binlog_ver = 4 00000019 | 35 2E 32 2E | server_ver = 5.2.0-MariaDB-alpha-debug-log ..... ... 0000004B | A1 A0 2C 4B | time_created = 1261215905 0000004F | 13 | common_header_len = 19 ------------------------ post_header_len ------------------------ 00000050 | 38 | 56 - START_EVENT_V3 [1] ..... ... 00000069 | 02 | 2 - INCIDENT_EVENT [26] 0000006A | 00 | 0 - RESERVED [27] ..... ... 00000081 | 00 | 0 - RESERVED [50] 00000082 | 00 | 0 - ANNOTATE_ROWS_EVENT [51] ************************ 2. Outline of Annotate_rows event behavior ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each Annotate_rows_log_event object has two private members describing the corresponding query: char *m_query_txt; uint m_query_len; When the object is created for writing to a binary log, this query is taken from 'thd' (for short, below we omit the 'Annotate_rows_log_event::' prefix as well as other implementation details): Annotate_rows_log_event(THD *thd) { m_query_txt = thd->query(); m_query_len = thd->query_length(); } When the object is read from a binary log, the query is taken from the buffer containing the binary log representation of the event (this buffer is allocated in Log_event object from which all Log events are derived): Annotate_rows_log_event(char *buf, uint event_len, Format_description_log_event *desc) { m_query_len = event_len - desc->common_header_len; m_query_txt = buf + desc->common_header_len; } The events are written to the binary log by the Log_event::write() member which calls virtual write_data_header() and write_data_body() members ("data header" and "post header" are synonym in replication terminology). In our case, data header is empty and data body is just the query: bool write_data_body(IO_CACHE *file) { return my_b_safe_write(file, (uchar*) m_query_txt, m_query_len); } Printing the event is just printing the query: void Annotate_rows_log_event::print(FILE *file, PRINT_EVENT_INFO *pinfo) { my_b_printf(&pinfo->head_cache, "\tQuery: `%s`\n", m_query_txt); } 3. How Master writes Annotate_rows events to the binary log ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The event is written to the binary log just before the group of Table_map events which precede corresponding Rows events (one query may generate several Table map events in the binary log, but the corresponding Annotate_rows event must be written only once before the first Table map event; hence the boolean variable 'with_annotate' below): int write_locked_table_maps(THD *thd) { ... bool with_annotate= thd->variables.binlog_annotate_rows_events; ... for (uint i= 0; i < ... <number of tables> ...; ++i) { ... thd->binlog_write_table_map(table, ..., with_annotate); with_annotate= 0; // write Annotate_event not more than once ... } ... } int THD::binlog_write_table_map(TABLE *table, ..., bool with_annotate) { ... Table_map_log_event the_event(...); ... if (with_annotate) { Annotate_rows_log_event anno(this); mysql_bin_log.write(&anno); } mysql_bin_log.write(&the_event); ... } 4. How slave treats replicate-annotate-rows-events option ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The replicate-annotate-rows-events option is treated just as the session value of the binlog_annotate_rows_events variable for the slave IO and SQL threads. This setting is done during initialization of these threads: pthread_handler_t handle_slave_io(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_IO); ... } pthread_handler_t handle_slave_sql(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_SQL); ... } int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type) { ... thd->variables.binlog_annotate_rows_events= opt_replicate_annotate_rows_events; ... } 5. How slave IO thread requests Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the replicate-annotate-rows-events option is not set on a slave, there is no need for master to send Annotate_rows events to this slave. The slave (or mysqlbinlog in remote case), before requesting binlog dump via the COM_BINLOG_DUMP command, informs the master whether it should send these events by executing the newly added COM_BINLOG_DUMP_OPTIONS_EXT server command: case COM_BINLOG_DUMP_OPTIONS_EXT: thd->binlog_dump_flags_ext= packet[0]; my_ok(thd); break; Note. We add this new command and don't use COM_BINLOG_DUMP to avoid possible conflicts with MySQL/Sun. 6. How master executes the request ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ case COM_BINLOG_DUMP: { ... flags= uint2korr(packet + 4); ... mysql_binlog_send(thd, ..., flags); ... } void mysql_binlog_send(THD* thd, ..., ushort flags) { ... Log_event::read_log_event(&log, packet, ...); ... if ((*packet)[EVENT_TYPE_OFFSET + 1] != ANNOTATE_ROWS_EVENT || flags & BINLOG_SEND_ANNOTATE_ROWS_EVENT) { my_net_write(net, packet->ptr(), packet->length()); } ... } 7. How slave SQL thread processes Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The slave processes each recieved event by "applying" it, i.e. by calling the Log_event::apply_event() function which in turn calls the virtual do_apply_event() member specific for each type of the event. int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev = next_event(rli); ... apply_event_and_update_pos(ev, ...); if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } int apply_event_and_update_pos(Log_event *ev, ...) { ... ev->apply_event(...); ... } int Log_event::apply_event(...) { return do_apply_event(...); } What does it mean to "apply" an Annotate_rows event? It means to set current thd query to that of the described by the event, i.e. to the query which caused the subsequent Rows events (see "How Master writes Annotate_rows events to the binary log" to follow what happens further when the subsequent Rows events are applied): int Annotate_rows_log_event::do_apply_event(...) { thd->set_query(m_query_txt, m_query_len); } NOTE. I am not sure, but possibly current values of thd->query and thd->query_length should be saved before calling set_query() and to be restored on the Annotate_rows_log_event object deletion. Is it really needed ? After calling this do_apply_event() function we may not delete the Annotate_rows_log_event object immediatedly (see exec_relay_log_event() above) because thd->query now points to the string inside this object. We may keep the pointer to this object in the Relay_log_info: class Relay_log_info { public: ... void set_annotate_event(Annotate_rows_log_event*); Annotate_rows_log_event* get_annotate_event(); void free_annotate_event(); ... private: Annotate_rows_log_event* m_annotate_event; }; The saved Annotate_rows object should be deleted when all corresponding Rows events will be processed: int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev= next_event(rli); ... apply_event_and_update_pos(ev, ...); if (rli->get_annotate_event() && is_last_rows_event(ev)) rli->free_annotate_event(); else if (ev->get_type_code() == ANNOTATE_ROWS_EVENT) rli->set_annotate_event((Annotate_rows_log_event*) ev); else if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } where bool is_last_rows_event(Log_event* ev) { Log_event_type type= ev->get_type_code(); if (IS_ROWS_EVENT_TYPE(type)) { Rows_log_event* rows= (Rows_log_event*)ev; return rows->get_flags(Rows_log_event::STMT_END_F); } return 0; } #define IS_ROWS_EVENT_TYPE(type) ((type) == WRITE_ROWS_EVENT || \ (type) == UPDATE_ROWS_EVENT || \ (type) == DELETE_ROWS_EVENT) 8. General remarks ~~~~~~~~~~~~~~~~~~ Kristian noticed that introducing new log event type should be coordinated somehow with MySQL/Sun: Kristian: The numeric code for this event must be assigned carefully. It should be coordinated with MySQL/Sun, otherwise we can get into a situation where MySQL uses the same numeric code for one event that MariaDB uses for ANNOTATE_ROWS_EVENT, which would make merging the two impossible. Alex: I reserved about 20 numbers not to have possible conflicts with MySQL. Kristian: Still, I think it would be appropriate to send a polite email to internals(a)lists.mysql.com about this and suggesting to reserve the event number. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Progress (by Alexi): Store in binlog text of statements that caused RBR events (47)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Store in binlog text of statements that caused RBR events CREATION DATE..: Sat, 15 Aug 2009, 23:48 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Knielsen, Serg CATEGORY.......: Server-Sprint TASK ID........: 47 (http://askmonty.org/worklog/?tid=47) VERSION........: Server-9.x STATUS.........: Code-Review PRIORITY.......: 60 WORKED HOURS...: 72 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 35 PROGRESS NOTES: -=-=(Alexi - Thu, 24 Jun 2010, 09:49)=-=- Final implementation cleanup, testing, help Percona with build issues related to the WL Worked 5 hours and estimate 0 hours remain (original estimate increased by 5 hours). -=-=(Alexi - Thu, 24 Jun 2010, 09:47)=-=- Making rpl- and binlog-tests stable w.r.t. adding new binlog events. Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Knielsen - Mon, 21 Jun 2010, 08:32)=-=- Final review. Assist with some problems applying the patch. Worked 1 hour and estimate 0 hours remain (original estimate increased by 1 hour). -=-=(Guest - Thu, 17 Jun 2010, 00:38)=-=- Dependency deleted: 39 no longer depends on 47 -=-=(Knielsen - Mon, 07 Jun 2010, 07:13)=-=- Help debug some test failures seen in Buildbot. Worked 6 hours and estimate 0 hours remain (original estimate increased by 6 hours). -=-=(Knielsen - Mon, 31 May 2010, 06:49)=-=- Help Alexi debug+fix some test problems in the patch. Worked 4 hours and estimate 0 hours remain (original estimate unchanged). -=-=(Knielsen - Tue, 25 May 2010, 08:29)=-=- Help debug strange problem in mysqlbinlog.test. Worked 1 hour and estimate 4 hours remain (original estimate unchanged). -=-=(Knielsen - Mon, 17 May 2010, 08:45)=-=- Merge with latest trunk and run Buildbot tests. Worked 1 hour and estimate 5 hours remain (original estimate unchanged). -=-=(Knielsen - Wed, 05 May 2010, 13:53)=-=- Review of fixes to first review done. No new issues found. Worked 2 hours and estimate 6 hours remain (original estimate unchanged). -=-=(Knielsen - Fri, 23 Apr 2010, 12:51)=-=- Status updated. --- /tmp/wklog.47.old.28747 2010-04-23 12:51:36.000000000 +0000 +++ /tmp/wklog.47.new.28747 2010-04-23 12:51:36.000000000 +0000 @@ -1 +1 @@ -In-Progress +Code-Review ------------------------------------------------------------ -=-=(View All Progress Notes, 37 total)=-=- http://askmonty.org/worklog/index.pl?tid=47&nolimit=1 DESCRIPTION: Store in binlog (and show in mysqlbinlog output) texts of statements that caused RBR events This is needed for (list from Monty): - Easier to understand why updates happened - Would make it easier to find out where in application things went wrong (as you can search for exact strings) - Allow one to filter things based on comments in the statement. The cost of this can be that the binlog will be approximately 2x in size (especially insert of big blob's would be a bit painful), so this should be an optional feature. HIGH-LEVEL SPECIFICATION: Content ~~~~~~~ 1. Annotate_rows_log_event 2. Server option: --binlog-annotate-rows-events 3. Server option: --replicate-annotate-rows-events 4. mysqlbinlog option: --print-annotate-rows-events 5. mysqlbinlog output 1. Annotate_rows_log_event [ ANNOTATE_ROWS_EVENT ] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Describes the query which caused the corresponding rows events. Has empty post-header and contains the query text in its data part. Example: ************************ ANNOTATE_ROWS_EVENT ************************ 00000220 | B6 A0 2C 4B | time_when = 1261215926 00000224 | 33 | event_type = 51 00000225 | 64 00 00 00 | server_id = 100 00000229 | 36 00 00 00 | event_len = 54 0000022D | 56 02 00 00 | log_pos = 00000256 00000231 | 00 00 | flags = <none> ------------------------ 00000233 | 49 4E 53 45 | query = "INSERT INTO t1 VALUES (1), (2), (3)" 00000237 | 52 54 20 49 | 0000023B | 4E 54 4F 20 | 0000023F | 74 31 20 56 | 00000243 | 41 4C 55 45 | 00000247 | 53 20 28 31 | 0000024B | 29 2C 20 28 | 0000024F | 32 29 2C 20 | 00000253 | 28 33 29 | ************************ In binary log, Annotate_rows event follows the (possible) 'BEGIN' Query event and precedes the first of Table map events which accompany the corresponding rows events. (See example in the "mysqlbinlog output" section below.) 2. Server option: --binlog-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the master to write Annotate_rows events to the binary log. * Variable Name: binlog_annotate_rows_events * Scope: Global & Session * Access Type: Dynamic * Data Type: bool * Default Value: OFF NOTE. Session values allows to annotate only some selected statements: ... SET SESSION binlog_annotate_rows_events=ON; ... statements to be annotated ... SET SESSION binlog_annotate_rows_events=OFF; ... statements not to be annotated ... 3. Server option: --replicate-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the slave to reproduce Annotate_rows events recieved from the master in its own binary log (sensible only in pair with log-slave-updates option). * Variable Name: replicate_annotate_rows_events * Scope: Global * Access Type: Read only * Data Type: bool * Default Value: OFF NOTE. Why do we additionally need this 'replicate' option? Why not to make the slave to reproduce this events when its binlog-annotate-rows-events global value is ON? Well, because, for example, we may want to configure the slave which should reproduce Annotate_rows events but has global binlog-annotate-rows-events = OFF meaning this to be the default value for the client threads (see also "How slave treats replicate-annotate-rows-events option" in LLD part). 4. mysqlbinlog option: --print-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ With this option, mysqlbinlog prints the content of Annotate_rows events (if the binary log does contain them). Without this option (i.e. by default), mysqlbinlog skips Annotate_rows events. 5. mysqlbinlog output ~~~~~~~~~~~~~~~~~~~~~ With --print-annotate-rows-events, mysqlbinlog outputs Annotate_rows events in a form like this: ... # at 1646 #091219 12:45:26 server id 100 end_log_pos 1714 Query thread_id=1 exec_time=0 error_code=0 SET TIMESTAMP=1261215926/*!*/; BEGIN /*!*/; # at 1714 # at 1812 # at 1853 # at 1894 # at 1938 #091219 12:45:26 server id 100 end_log_pos 1812 Query: `DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.a=t2.a AND t2.a=t3.a` #091219 12:45:26 server id 100 end_log_pos 1853 Table_map: `test`.`t1` mapped to number 16 #091219 12:45:26 server id 100 end_log_pos 1894 Table_map: `test`.`t2` mapped to number 17 #091219 12:45:26 server id 100 end_log_pos 1938 Delete_rows: table id 16 #091219 12:45:26 server id 100 end_log_pos 1982 Delete_rows: table id 17 flags: STMT_END_F ... LOW-LEVEL DESIGN: Content ~~~~~~~ 1. Annotate_rows event number 2. Outline of Annotate_rows event behavior 3. How Master writes Annotate_rows events to the binary log 4. How slave treats replicate-annotate-rows-events option 5. How slave IO thread requests Annotate_rows events 6. How master executes the request 7. How slave SQL thread processes Annotate_rows events 8. General remarks 1. Annotate_rows event number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To avoid possible event numbers conflict with MySQL/Sun, we leave a gap between the last MySQL event number and the Annotate_rows event number: enum Log_event_type { ... INCIDENT_EVENT= 26, // New MySQL event numbers are to be added here MYSQL_EVENTS_END, MARIA_EVENTS_BEGIN= 51, // New Maria event numbers start from here ANNOTATE_ROWS_EVENT= 51, ENUM_END_EVENT }; together with the corresponding extension of 'post_header_len' array in the Format description event. (This extension does not affect the compatibility of the binary log). Here is how Format description event looks like with this extension: ************************ FORMAT_DESCRIPTION_EVENT ************************ 00000004 | A1 A0 2C 4B | time_when = 1261215905 00000008 | 0F | event_type = 15 00000009 | 64 00 00 00 | server_id = 100 0000000D | 7F 00 00 00 | event_len = 127 00000011 | 83 00 00 00 | log_pos = 00000083 00000015 | 01 00 | flags = LOG_EVENT_BINLOG_IN_USE_F ------------------------ 00000017 | 04 00 | binlog_ver = 4 00000019 | 35 2E 32 2E | server_ver = 5.2.0-MariaDB-alpha-debug-log ..... ... 0000004B | A1 A0 2C 4B | time_created = 1261215905 0000004F | 13 | common_header_len = 19 ------------------------ post_header_len ------------------------ 00000050 | 38 | 56 - START_EVENT_V3 [1] ..... ... 00000069 | 02 | 2 - INCIDENT_EVENT [26] 0000006A | 00 | 0 - RESERVED [27] ..... ... 00000081 | 00 | 0 - RESERVED [50] 00000082 | 00 | 0 - ANNOTATE_ROWS_EVENT [51] ************************ 2. Outline of Annotate_rows event behavior ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each Annotate_rows_log_event object has two private members describing the corresponding query: char *m_query_txt; uint m_query_len; When the object is created for writing to a binary log, this query is taken from 'thd' (for short, below we omit the 'Annotate_rows_log_event::' prefix as well as other implementation details): Annotate_rows_log_event(THD *thd) { m_query_txt = thd->query(); m_query_len = thd->query_length(); } When the object is read from a binary log, the query is taken from the buffer containing the binary log representation of the event (this buffer is allocated in Log_event object from which all Log events are derived): Annotate_rows_log_event(char *buf, uint event_len, Format_description_log_event *desc) { m_query_len = event_len - desc->common_header_len; m_query_txt = buf + desc->common_header_len; } The events are written to the binary log by the Log_event::write() member which calls virtual write_data_header() and write_data_body() members ("data header" and "post header" are synonym in replication terminology). In our case, data header is empty and data body is just the query: bool write_data_body(IO_CACHE *file) { return my_b_safe_write(file, (uchar*) m_query_txt, m_query_len); } Printing the event is just printing the query: void Annotate_rows_log_event::print(FILE *file, PRINT_EVENT_INFO *pinfo) { my_b_printf(&pinfo->head_cache, "\tQuery: `%s`\n", m_query_txt); } 3. How Master writes Annotate_rows events to the binary log ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The event is written to the binary log just before the group of Table_map events which precede corresponding Rows events (one query may generate several Table map events in the binary log, but the corresponding Annotate_rows event must be written only once before the first Table map event; hence the boolean variable 'with_annotate' below): int write_locked_table_maps(THD *thd) { ... bool with_annotate= thd->variables.binlog_annotate_rows_events; ... for (uint i= 0; i < ... <number of tables> ...; ++i) { ... thd->binlog_write_table_map(table, ..., with_annotate); with_annotate= 0; // write Annotate_event not more than once ... } ... } int THD::binlog_write_table_map(TABLE *table, ..., bool with_annotate) { ... Table_map_log_event the_event(...); ... if (with_annotate) { Annotate_rows_log_event anno(this); mysql_bin_log.write(&anno); } mysql_bin_log.write(&the_event); ... } 4. How slave treats replicate-annotate-rows-events option ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The replicate-annotate-rows-events option is treated just as the session value of the binlog_annotate_rows_events variable for the slave IO and SQL threads. This setting is done during initialization of these threads: pthread_handler_t handle_slave_io(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_IO); ... } pthread_handler_t handle_slave_sql(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_SQL); ... } int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type) { ... thd->variables.binlog_annotate_rows_events= opt_replicate_annotate_rows_events; ... } 5. How slave IO thread requests Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the replicate-annotate-rows-events option is not set on a slave, there is no need for master to send Annotate_rows events to this slave. The slave (or mysqlbinlog in remote case), before requesting binlog dump via the COM_BINLOG_DUMP command, informs the master whether it should send these events by executing the newly added COM_BINLOG_DUMP_OPTIONS_EXT server command: case COM_BINLOG_DUMP_OPTIONS_EXT: thd->binlog_dump_flags_ext= packet[0]; my_ok(thd); break; Note. We add this new command and don't use COM_BINLOG_DUMP to avoid possible conflicts with MySQL/Sun. 6. How master executes the request ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ case COM_BINLOG_DUMP: { ... flags= uint2korr(packet + 4); ... mysql_binlog_send(thd, ..., flags); ... } void mysql_binlog_send(THD* thd, ..., ushort flags) { ... Log_event::read_log_event(&log, packet, ...); ... if ((*packet)[EVENT_TYPE_OFFSET + 1] != ANNOTATE_ROWS_EVENT || flags & BINLOG_SEND_ANNOTATE_ROWS_EVENT) { my_net_write(net, packet->ptr(), packet->length()); } ... } 7. How slave SQL thread processes Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The slave processes each recieved event by "applying" it, i.e. by calling the Log_event::apply_event() function which in turn calls the virtual do_apply_event() member specific for each type of the event. int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev = next_event(rli); ... apply_event_and_update_pos(ev, ...); if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } int apply_event_and_update_pos(Log_event *ev, ...) { ... ev->apply_event(...); ... } int Log_event::apply_event(...) { return do_apply_event(...); } What does it mean to "apply" an Annotate_rows event? It means to set current thd query to that of the described by the event, i.e. to the query which caused the subsequent Rows events (see "How Master writes Annotate_rows events to the binary log" to follow what happens further when the subsequent Rows events are applied): int Annotate_rows_log_event::do_apply_event(...) { thd->set_query(m_query_txt, m_query_len); } NOTE. I am not sure, but possibly current values of thd->query and thd->query_length should be saved before calling set_query() and to be restored on the Annotate_rows_log_event object deletion. Is it really needed ? After calling this do_apply_event() function we may not delete the Annotate_rows_log_event object immediatedly (see exec_relay_log_event() above) because thd->query now points to the string inside this object. We may keep the pointer to this object in the Relay_log_info: class Relay_log_info { public: ... void set_annotate_event(Annotate_rows_log_event*); Annotate_rows_log_event* get_annotate_event(); void free_annotate_event(); ... private: Annotate_rows_log_event* m_annotate_event; }; The saved Annotate_rows object should be deleted when all corresponding Rows events will be processed: int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev= next_event(rli); ... apply_event_and_update_pos(ev, ...); if (rli->get_annotate_event() && is_last_rows_event(ev)) rli->free_annotate_event(); else if (ev->get_type_code() == ANNOTATE_ROWS_EVENT) rli->set_annotate_event((Annotate_rows_log_event*) ev); else if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } where bool is_last_rows_event(Log_event* ev) { Log_event_type type= ev->get_type_code(); if (IS_ROWS_EVENT_TYPE(type)) { Rows_log_event* rows= (Rows_log_event*)ev; return rows->get_flags(Rows_log_event::STMT_END_F); } return 0; } #define IS_ROWS_EVENT_TYPE(type) ((type) == WRITE_ROWS_EVENT || \ (type) == UPDATE_ROWS_EVENT || \ (type) == DELETE_ROWS_EVENT) 8. General remarks ~~~~~~~~~~~~~~~~~~ Kristian noticed that introducing new log event type should be coordinated somehow with MySQL/Sun: Kristian: The numeric code for this event must be assigned carefully. It should be coordinated with MySQL/Sun, otherwise we can get into a situation where MySQL uses the same numeric code for one event that MariaDB uses for ANNOTATE_ROWS_EVENT, which would make merging the two impossible. Alex: I reserved about 20 numbers not to have possible conflicts with MySQL. Kristian: Still, I think it would be appropriate to send a polite email to internals(a)lists.mysql.com about this and suggesting to reserve the event number. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Progress (by Alexi): Store in binlog text of statements that caused RBR events (47)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Store in binlog text of statements that caused RBR events CREATION DATE..: Sat, 15 Aug 2009, 23:48 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Knielsen, Serg CATEGORY.......: Server-Sprint TASK ID........: 47 (http://askmonty.org/worklog/?tid=47) VERSION........: Server-9.x STATUS.........: Code-Review PRIORITY.......: 60 WORKED HOURS...: 72 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 35 PROGRESS NOTES: -=-=(Alexi - Thu, 24 Jun 2010, 09:49)=-=- Final implementation cleanup, testing, help Percona with build issues related to the WL Worked 5 hours and estimate 0 hours remain (original estimate increased by 5 hours). -=-=(Alexi - Thu, 24 Jun 2010, 09:47)=-=- Making rpl- and binlog-tests stable w.r.t. adding new binlog events. Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Knielsen - Mon, 21 Jun 2010, 08:32)=-=- Final review. Assist with some problems applying the patch. Worked 1 hour and estimate 0 hours remain (original estimate increased by 1 hour). -=-=(Guest - Thu, 17 Jun 2010, 00:38)=-=- Dependency deleted: 39 no longer depends on 47 -=-=(Knielsen - Mon, 07 Jun 2010, 07:13)=-=- Help debug some test failures seen in Buildbot. Worked 6 hours and estimate 0 hours remain (original estimate increased by 6 hours). -=-=(Knielsen - Mon, 31 May 2010, 06:49)=-=- Help Alexi debug+fix some test problems in the patch. Worked 4 hours and estimate 0 hours remain (original estimate unchanged). -=-=(Knielsen - Tue, 25 May 2010, 08:29)=-=- Help debug strange problem in mysqlbinlog.test. Worked 1 hour and estimate 4 hours remain (original estimate unchanged). -=-=(Knielsen - Mon, 17 May 2010, 08:45)=-=- Merge with latest trunk and run Buildbot tests. Worked 1 hour and estimate 5 hours remain (original estimate unchanged). -=-=(Knielsen - Wed, 05 May 2010, 13:53)=-=- Review of fixes to first review done. No new issues found. Worked 2 hours and estimate 6 hours remain (original estimate unchanged). -=-=(Knielsen - Fri, 23 Apr 2010, 12:51)=-=- Status updated. --- /tmp/wklog.47.old.28747 2010-04-23 12:51:36.000000000 +0000 +++ /tmp/wklog.47.new.28747 2010-04-23 12:51:36.000000000 +0000 @@ -1 +1 @@ -In-Progress +Code-Review ------------------------------------------------------------ -=-=(View All Progress Notes, 37 total)=-=- http://askmonty.org/worklog/index.pl?tid=47&nolimit=1 DESCRIPTION: Store in binlog (and show in mysqlbinlog output) texts of statements that caused RBR events This is needed for (list from Monty): - Easier to understand why updates happened - Would make it easier to find out where in application things went wrong (as you can search for exact strings) - Allow one to filter things based on comments in the statement. The cost of this can be that the binlog will be approximately 2x in size (especially insert of big blob's would be a bit painful), so this should be an optional feature. HIGH-LEVEL SPECIFICATION: Content ~~~~~~~ 1. Annotate_rows_log_event 2. Server option: --binlog-annotate-rows-events 3. Server option: --replicate-annotate-rows-events 4. mysqlbinlog option: --print-annotate-rows-events 5. mysqlbinlog output 1. Annotate_rows_log_event [ ANNOTATE_ROWS_EVENT ] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Describes the query which caused the corresponding rows events. Has empty post-header and contains the query text in its data part. Example: ************************ ANNOTATE_ROWS_EVENT ************************ 00000220 | B6 A0 2C 4B | time_when = 1261215926 00000224 | 33 | event_type = 51 00000225 | 64 00 00 00 | server_id = 100 00000229 | 36 00 00 00 | event_len = 54 0000022D | 56 02 00 00 | log_pos = 00000256 00000231 | 00 00 | flags = <none> ------------------------ 00000233 | 49 4E 53 45 | query = "INSERT INTO t1 VALUES (1), (2), (3)" 00000237 | 52 54 20 49 | 0000023B | 4E 54 4F 20 | 0000023F | 74 31 20 56 | 00000243 | 41 4C 55 45 | 00000247 | 53 20 28 31 | 0000024B | 29 2C 20 28 | 0000024F | 32 29 2C 20 | 00000253 | 28 33 29 | ************************ In binary log, Annotate_rows event follows the (possible) 'BEGIN' Query event and precedes the first of Table map events which accompany the corresponding rows events. (See example in the "mysqlbinlog output" section below.) 2. Server option: --binlog-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the master to write Annotate_rows events to the binary log. * Variable Name: binlog_annotate_rows_events * Scope: Global & Session * Access Type: Dynamic * Data Type: bool * Default Value: OFF NOTE. Session values allows to annotate only some selected statements: ... SET SESSION binlog_annotate_rows_events=ON; ... statements to be annotated ... SET SESSION binlog_annotate_rows_events=OFF; ... statements not to be annotated ... 3. Server option: --replicate-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the slave to reproduce Annotate_rows events recieved from the master in its own binary log (sensible only in pair with log-slave-updates option). * Variable Name: replicate_annotate_rows_events * Scope: Global * Access Type: Read only * Data Type: bool * Default Value: OFF NOTE. Why do we additionally need this 'replicate' option? Why not to make the slave to reproduce this events when its binlog-annotate-rows-events global value is ON? Well, because, for example, we may want to configure the slave which should reproduce Annotate_rows events but has global binlog-annotate-rows-events = OFF meaning this to be the default value for the client threads (see also "How slave treats replicate-annotate-rows-events option" in LLD part). 4. mysqlbinlog option: --print-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ With this option, mysqlbinlog prints the content of Annotate_rows events (if the binary log does contain them). Without this option (i.e. by default), mysqlbinlog skips Annotate_rows events. 5. mysqlbinlog output ~~~~~~~~~~~~~~~~~~~~~ With --print-annotate-rows-events, mysqlbinlog outputs Annotate_rows events in a form like this: ... # at 1646 #091219 12:45:26 server id 100 end_log_pos 1714 Query thread_id=1 exec_time=0 error_code=0 SET TIMESTAMP=1261215926/*!*/; BEGIN /*!*/; # at 1714 # at 1812 # at 1853 # at 1894 # at 1938 #091219 12:45:26 server id 100 end_log_pos 1812 Query: `DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.a=t2.a AND t2.a=t3.a` #091219 12:45:26 server id 100 end_log_pos 1853 Table_map: `test`.`t1` mapped to number 16 #091219 12:45:26 server id 100 end_log_pos 1894 Table_map: `test`.`t2` mapped to number 17 #091219 12:45:26 server id 100 end_log_pos 1938 Delete_rows: table id 16 #091219 12:45:26 server id 100 end_log_pos 1982 Delete_rows: table id 17 flags: STMT_END_F ... LOW-LEVEL DESIGN: Content ~~~~~~~ 1. Annotate_rows event number 2. Outline of Annotate_rows event behavior 3. How Master writes Annotate_rows events to the binary log 4. How slave treats replicate-annotate-rows-events option 5. How slave IO thread requests Annotate_rows events 6. How master executes the request 7. How slave SQL thread processes Annotate_rows events 8. General remarks 1. Annotate_rows event number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To avoid possible event numbers conflict with MySQL/Sun, we leave a gap between the last MySQL event number and the Annotate_rows event number: enum Log_event_type { ... INCIDENT_EVENT= 26, // New MySQL event numbers are to be added here MYSQL_EVENTS_END, MARIA_EVENTS_BEGIN= 51, // New Maria event numbers start from here ANNOTATE_ROWS_EVENT= 51, ENUM_END_EVENT }; together with the corresponding extension of 'post_header_len' array in the Format description event. (This extension does not affect the compatibility of the binary log). Here is how Format description event looks like with this extension: ************************ FORMAT_DESCRIPTION_EVENT ************************ 00000004 | A1 A0 2C 4B | time_when = 1261215905 00000008 | 0F | event_type = 15 00000009 | 64 00 00 00 | server_id = 100 0000000D | 7F 00 00 00 | event_len = 127 00000011 | 83 00 00 00 | log_pos = 00000083 00000015 | 01 00 | flags = LOG_EVENT_BINLOG_IN_USE_F ------------------------ 00000017 | 04 00 | binlog_ver = 4 00000019 | 35 2E 32 2E | server_ver = 5.2.0-MariaDB-alpha-debug-log ..... ... 0000004B | A1 A0 2C 4B | time_created = 1261215905 0000004F | 13 | common_header_len = 19 ------------------------ post_header_len ------------------------ 00000050 | 38 | 56 - START_EVENT_V3 [1] ..... ... 00000069 | 02 | 2 - INCIDENT_EVENT [26] 0000006A | 00 | 0 - RESERVED [27] ..... ... 00000081 | 00 | 0 - RESERVED [50] 00000082 | 00 | 0 - ANNOTATE_ROWS_EVENT [51] ************************ 2. Outline of Annotate_rows event behavior ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each Annotate_rows_log_event object has two private members describing the corresponding query: char *m_query_txt; uint m_query_len; When the object is created for writing to a binary log, this query is taken from 'thd' (for short, below we omit the 'Annotate_rows_log_event::' prefix as well as other implementation details): Annotate_rows_log_event(THD *thd) { m_query_txt = thd->query(); m_query_len = thd->query_length(); } When the object is read from a binary log, the query is taken from the buffer containing the binary log representation of the event (this buffer is allocated in Log_event object from which all Log events are derived): Annotate_rows_log_event(char *buf, uint event_len, Format_description_log_event *desc) { m_query_len = event_len - desc->common_header_len; m_query_txt = buf + desc->common_header_len; } The events are written to the binary log by the Log_event::write() member which calls virtual write_data_header() and write_data_body() members ("data header" and "post header" are synonym in replication terminology). In our case, data header is empty and data body is just the query: bool write_data_body(IO_CACHE *file) { return my_b_safe_write(file, (uchar*) m_query_txt, m_query_len); } Printing the event is just printing the query: void Annotate_rows_log_event::print(FILE *file, PRINT_EVENT_INFO *pinfo) { my_b_printf(&pinfo->head_cache, "\tQuery: `%s`\n", m_query_txt); } 3. How Master writes Annotate_rows events to the binary log ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The event is written to the binary log just before the group of Table_map events which precede corresponding Rows events (one query may generate several Table map events in the binary log, but the corresponding Annotate_rows event must be written only once before the first Table map event; hence the boolean variable 'with_annotate' below): int write_locked_table_maps(THD *thd) { ... bool with_annotate= thd->variables.binlog_annotate_rows_events; ... for (uint i= 0; i < ... <number of tables> ...; ++i) { ... thd->binlog_write_table_map(table, ..., with_annotate); with_annotate= 0; // write Annotate_event not more than once ... } ... } int THD::binlog_write_table_map(TABLE *table, ..., bool with_annotate) { ... Table_map_log_event the_event(...); ... if (with_annotate) { Annotate_rows_log_event anno(this); mysql_bin_log.write(&anno); } mysql_bin_log.write(&the_event); ... } 4. How slave treats replicate-annotate-rows-events option ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The replicate-annotate-rows-events option is treated just as the session value of the binlog_annotate_rows_events variable for the slave IO and SQL threads. This setting is done during initialization of these threads: pthread_handler_t handle_slave_io(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_IO); ... } pthread_handler_t handle_slave_sql(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_SQL); ... } int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type) { ... thd->variables.binlog_annotate_rows_events= opt_replicate_annotate_rows_events; ... } 5. How slave IO thread requests Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the replicate-annotate-rows-events option is not set on a slave, there is no need for master to send Annotate_rows events to this slave. The slave (or mysqlbinlog in remote case), before requesting binlog dump via the COM_BINLOG_DUMP command, informs the master whether it should send these events by executing the newly added COM_BINLOG_DUMP_OPTIONS_EXT server command: case COM_BINLOG_DUMP_OPTIONS_EXT: thd->binlog_dump_flags_ext= packet[0]; my_ok(thd); break; Note. We add this new command and don't use COM_BINLOG_DUMP to avoid possible conflicts with MySQL/Sun. 6. How master executes the request ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ case COM_BINLOG_DUMP: { ... flags= uint2korr(packet + 4); ... mysql_binlog_send(thd, ..., flags); ... } void mysql_binlog_send(THD* thd, ..., ushort flags) { ... Log_event::read_log_event(&log, packet, ...); ... if ((*packet)[EVENT_TYPE_OFFSET + 1] != ANNOTATE_ROWS_EVENT || flags & BINLOG_SEND_ANNOTATE_ROWS_EVENT) { my_net_write(net, packet->ptr(), packet->length()); } ... } 7. How slave SQL thread processes Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The slave processes each recieved event by "applying" it, i.e. by calling the Log_event::apply_event() function which in turn calls the virtual do_apply_event() member specific for each type of the event. int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev = next_event(rli); ... apply_event_and_update_pos(ev, ...); if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } int apply_event_and_update_pos(Log_event *ev, ...) { ... ev->apply_event(...); ... } int Log_event::apply_event(...) { return do_apply_event(...); } What does it mean to "apply" an Annotate_rows event? It means to set current thd query to that of the described by the event, i.e. to the query which caused the subsequent Rows events (see "How Master writes Annotate_rows events to the binary log" to follow what happens further when the subsequent Rows events are applied): int Annotate_rows_log_event::do_apply_event(...) { thd->set_query(m_query_txt, m_query_len); } NOTE. I am not sure, but possibly current values of thd->query and thd->query_length should be saved before calling set_query() and to be restored on the Annotate_rows_log_event object deletion. Is it really needed ? After calling this do_apply_event() function we may not delete the Annotate_rows_log_event object immediatedly (see exec_relay_log_event() above) because thd->query now points to the string inside this object. We may keep the pointer to this object in the Relay_log_info: class Relay_log_info { public: ... void set_annotate_event(Annotate_rows_log_event*); Annotate_rows_log_event* get_annotate_event(); void free_annotate_event(); ... private: Annotate_rows_log_event* m_annotate_event; }; The saved Annotate_rows object should be deleted when all corresponding Rows events will be processed: int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev= next_event(rli); ... apply_event_and_update_pos(ev, ...); if (rli->get_annotate_event() && is_last_rows_event(ev)) rli->free_annotate_event(); else if (ev->get_type_code() == ANNOTATE_ROWS_EVENT) rli->set_annotate_event((Annotate_rows_log_event*) ev); else if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } where bool is_last_rows_event(Log_event* ev) { Log_event_type type= ev->get_type_code(); if (IS_ROWS_EVENT_TYPE(type)) { Rows_log_event* rows= (Rows_log_event*)ev; return rows->get_flags(Rows_log_event::STMT_END_F); } return 0; } #define IS_ROWS_EVENT_TYPE(type) ((type) == WRITE_ROWS_EVENT || \ (type) == UPDATE_ROWS_EVENT || \ (type) == DELETE_ROWS_EVENT) 8. General remarks ~~~~~~~~~~~~~~~~~~ Kristian noticed that introducing new log event type should be coordinated somehow with MySQL/Sun: Kristian: The numeric code for this event must be assigned carefully. It should be coordinated with MySQL/Sun, otherwise we can get into a situation where MySQL uses the same numeric code for one event that MariaDB uses for ANNOTATE_ROWS_EVENT, which would make merging the two impossible. Alex: I reserved about 20 numbers not to have possible conflicts with MySQL. Kristian: Still, I think it would be appropriate to send a polite email to internals(a)lists.mysql.com about this and suggesting to reserve the event number. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Progress (by Alexi): Store in binlog text of statements that caused RBR events (47)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Store in binlog text of statements that caused RBR events CREATION DATE..: Sat, 15 Aug 2009, 23:48 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Knielsen, Serg CATEGORY.......: Server-Sprint TASK ID........: 47 (http://askmonty.org/worklog/?tid=47) VERSION........: Server-9.x STATUS.........: Code-Review PRIORITY.......: 60 WORKED HOURS...: 67 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 35 PROGRESS NOTES: -=-=(Alexi - Thu, 24 Jun 2010, 09:47)=-=- Making rpl- and binlog-tests stable w.r.t. adding new binlog events. Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Knielsen - Mon, 21 Jun 2010, 08:32)=-=- Final review. Assist with some problems applying the patch. Worked 1 hour and estimate 0 hours remain (original estimate increased by 1 hour). -=-=(Guest - Thu, 17 Jun 2010, 00:38)=-=- Dependency deleted: 39 no longer depends on 47 -=-=(Knielsen - Mon, 07 Jun 2010, 07:13)=-=- Help debug some test failures seen in Buildbot. Worked 6 hours and estimate 0 hours remain (original estimate increased by 6 hours). -=-=(Knielsen - Mon, 31 May 2010, 06:49)=-=- Help Alexi debug+fix some test problems in the patch. Worked 4 hours and estimate 0 hours remain (original estimate unchanged). -=-=(Knielsen - Tue, 25 May 2010, 08:29)=-=- Help debug strange problem in mysqlbinlog.test. Worked 1 hour and estimate 4 hours remain (original estimate unchanged). -=-=(Knielsen - Mon, 17 May 2010, 08:45)=-=- Merge with latest trunk and run Buildbot tests. Worked 1 hour and estimate 5 hours remain (original estimate unchanged). -=-=(Knielsen - Wed, 05 May 2010, 13:53)=-=- Review of fixes to first review done. No new issues found. Worked 2 hours and estimate 6 hours remain (original estimate unchanged). -=-=(Knielsen - Fri, 23 Apr 2010, 12:51)=-=- Status updated. --- /tmp/wklog.47.old.28747 2010-04-23 12:51:36.000000000 +0000 +++ /tmp/wklog.47.new.28747 2010-04-23 12:51:36.000000000 +0000 @@ -1 +1 @@ -In-Progress +Code-Review -=-=(Knielsen - Tue, 06 Apr 2010, 15:26)=-=- Code review (mailed to maria-developers@). Worked 7 hours and estimate 8 hours remain (original estimate unchanged). ------------------------------------------------------------ -=-=(View All Progress Notes, 36 total)=-=- http://askmonty.org/worklog/index.pl?tid=47&nolimit=1 DESCRIPTION: Store in binlog (and show in mysqlbinlog output) texts of statements that caused RBR events This is needed for (list from Monty): - Easier to understand why updates happened - Would make it easier to find out where in application things went wrong (as you can search for exact strings) - Allow one to filter things based on comments in the statement. The cost of this can be that the binlog will be approximately 2x in size (especially insert of big blob's would be a bit painful), so this should be an optional feature. HIGH-LEVEL SPECIFICATION: Content ~~~~~~~ 1. Annotate_rows_log_event 2. Server option: --binlog-annotate-rows-events 3. Server option: --replicate-annotate-rows-events 4. mysqlbinlog option: --print-annotate-rows-events 5. mysqlbinlog output 1. Annotate_rows_log_event [ ANNOTATE_ROWS_EVENT ] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Describes the query which caused the corresponding rows events. Has empty post-header and contains the query text in its data part. Example: ************************ ANNOTATE_ROWS_EVENT ************************ 00000220 | B6 A0 2C 4B | time_when = 1261215926 00000224 | 33 | event_type = 51 00000225 | 64 00 00 00 | server_id = 100 00000229 | 36 00 00 00 | event_len = 54 0000022D | 56 02 00 00 | log_pos = 00000256 00000231 | 00 00 | flags = <none> ------------------------ 00000233 | 49 4E 53 45 | query = "INSERT INTO t1 VALUES (1), (2), (3)" 00000237 | 52 54 20 49 | 0000023B | 4E 54 4F 20 | 0000023F | 74 31 20 56 | 00000243 | 41 4C 55 45 | 00000247 | 53 20 28 31 | 0000024B | 29 2C 20 28 | 0000024F | 32 29 2C 20 | 00000253 | 28 33 29 | ************************ In binary log, Annotate_rows event follows the (possible) 'BEGIN' Query event and precedes the first of Table map events which accompany the corresponding rows events. (See example in the "mysqlbinlog output" section below.) 2. Server option: --binlog-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the master to write Annotate_rows events to the binary log. * Variable Name: binlog_annotate_rows_events * Scope: Global & Session * Access Type: Dynamic * Data Type: bool * Default Value: OFF NOTE. Session values allows to annotate only some selected statements: ... SET SESSION binlog_annotate_rows_events=ON; ... statements to be annotated ... SET SESSION binlog_annotate_rows_events=OFF; ... statements not to be annotated ... 3. Server option: --replicate-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the slave to reproduce Annotate_rows events recieved from the master in its own binary log (sensible only in pair with log-slave-updates option). * Variable Name: replicate_annotate_rows_events * Scope: Global * Access Type: Read only * Data Type: bool * Default Value: OFF NOTE. Why do we additionally need this 'replicate' option? Why not to make the slave to reproduce this events when its binlog-annotate-rows-events global value is ON? Well, because, for example, we may want to configure the slave which should reproduce Annotate_rows events but has global binlog-annotate-rows-events = OFF meaning this to be the default value for the client threads (see also "How slave treats replicate-annotate-rows-events option" in LLD part). 4. mysqlbinlog option: --print-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ With this option, mysqlbinlog prints the content of Annotate_rows events (if the binary log does contain them). Without this option (i.e. by default), mysqlbinlog skips Annotate_rows events. 5. mysqlbinlog output ~~~~~~~~~~~~~~~~~~~~~ With --print-annotate-rows-events, mysqlbinlog outputs Annotate_rows events in a form like this: ... # at 1646 #091219 12:45:26 server id 100 end_log_pos 1714 Query thread_id=1 exec_time=0 error_code=0 SET TIMESTAMP=1261215926/*!*/; BEGIN /*!*/; # at 1714 # at 1812 # at 1853 # at 1894 # at 1938 #091219 12:45:26 server id 100 end_log_pos 1812 Query: `DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.a=t2.a AND t2.a=t3.a` #091219 12:45:26 server id 100 end_log_pos 1853 Table_map: `test`.`t1` mapped to number 16 #091219 12:45:26 server id 100 end_log_pos 1894 Table_map: `test`.`t2` mapped to number 17 #091219 12:45:26 server id 100 end_log_pos 1938 Delete_rows: table id 16 #091219 12:45:26 server id 100 end_log_pos 1982 Delete_rows: table id 17 flags: STMT_END_F ... LOW-LEVEL DESIGN: Content ~~~~~~~ 1. Annotate_rows event number 2. Outline of Annotate_rows event behavior 3. How Master writes Annotate_rows events to the binary log 4. How slave treats replicate-annotate-rows-events option 5. How slave IO thread requests Annotate_rows events 6. How master executes the request 7. How slave SQL thread processes Annotate_rows events 8. General remarks 1. Annotate_rows event number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To avoid possible event numbers conflict with MySQL/Sun, we leave a gap between the last MySQL event number and the Annotate_rows event number: enum Log_event_type { ... INCIDENT_EVENT= 26, // New MySQL event numbers are to be added here MYSQL_EVENTS_END, MARIA_EVENTS_BEGIN= 51, // New Maria event numbers start from here ANNOTATE_ROWS_EVENT= 51, ENUM_END_EVENT }; together with the corresponding extension of 'post_header_len' array in the Format description event. (This extension does not affect the compatibility of the binary log). Here is how Format description event looks like with this extension: ************************ FORMAT_DESCRIPTION_EVENT ************************ 00000004 | A1 A0 2C 4B | time_when = 1261215905 00000008 | 0F | event_type = 15 00000009 | 64 00 00 00 | server_id = 100 0000000D | 7F 00 00 00 | event_len = 127 00000011 | 83 00 00 00 | log_pos = 00000083 00000015 | 01 00 | flags = LOG_EVENT_BINLOG_IN_USE_F ------------------------ 00000017 | 04 00 | binlog_ver = 4 00000019 | 35 2E 32 2E | server_ver = 5.2.0-MariaDB-alpha-debug-log ..... ... 0000004B | A1 A0 2C 4B | time_created = 1261215905 0000004F | 13 | common_header_len = 19 ------------------------ post_header_len ------------------------ 00000050 | 38 | 56 - START_EVENT_V3 [1] ..... ... 00000069 | 02 | 2 - INCIDENT_EVENT [26] 0000006A | 00 | 0 - RESERVED [27] ..... ... 00000081 | 00 | 0 - RESERVED [50] 00000082 | 00 | 0 - ANNOTATE_ROWS_EVENT [51] ************************ 2. Outline of Annotate_rows event behavior ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each Annotate_rows_log_event object has two private members describing the corresponding query: char *m_query_txt; uint m_query_len; When the object is created for writing to a binary log, this query is taken from 'thd' (for short, below we omit the 'Annotate_rows_log_event::' prefix as well as other implementation details): Annotate_rows_log_event(THD *thd) { m_query_txt = thd->query(); m_query_len = thd->query_length(); } When the object is read from a binary log, the query is taken from the buffer containing the binary log representation of the event (this buffer is allocated in Log_event object from which all Log events are derived): Annotate_rows_log_event(char *buf, uint event_len, Format_description_log_event *desc) { m_query_len = event_len - desc->common_header_len; m_query_txt = buf + desc->common_header_len; } The events are written to the binary log by the Log_event::write() member which calls virtual write_data_header() and write_data_body() members ("data header" and "post header" are synonym in replication terminology). In our case, data header is empty and data body is just the query: bool write_data_body(IO_CACHE *file) { return my_b_safe_write(file, (uchar*) m_query_txt, m_query_len); } Printing the event is just printing the query: void Annotate_rows_log_event::print(FILE *file, PRINT_EVENT_INFO *pinfo) { my_b_printf(&pinfo->head_cache, "\tQuery: `%s`\n", m_query_txt); } 3. How Master writes Annotate_rows events to the binary log ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The event is written to the binary log just before the group of Table_map events which precede corresponding Rows events (one query may generate several Table map events in the binary log, but the corresponding Annotate_rows event must be written only once before the first Table map event; hence the boolean variable 'with_annotate' below): int write_locked_table_maps(THD *thd) { ... bool with_annotate= thd->variables.binlog_annotate_rows_events; ... for (uint i= 0; i < ... <number of tables> ...; ++i) { ... thd->binlog_write_table_map(table, ..., with_annotate); with_annotate= 0; // write Annotate_event not more than once ... } ... } int THD::binlog_write_table_map(TABLE *table, ..., bool with_annotate) { ... Table_map_log_event the_event(...); ... if (with_annotate) { Annotate_rows_log_event anno(this); mysql_bin_log.write(&anno); } mysql_bin_log.write(&the_event); ... } 4. How slave treats replicate-annotate-rows-events option ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The replicate-annotate-rows-events option is treated just as the session value of the binlog_annotate_rows_events variable for the slave IO and SQL threads. This setting is done during initialization of these threads: pthread_handler_t handle_slave_io(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_IO); ... } pthread_handler_t handle_slave_sql(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_SQL); ... } int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type) { ... thd->variables.binlog_annotate_rows_events= opt_replicate_annotate_rows_events; ... } 5. How slave IO thread requests Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the replicate-annotate-rows-events option is not set on a slave, there is no need for master to send Annotate_rows events to this slave. The slave (or mysqlbinlog in remote case), before requesting binlog dump via the COM_BINLOG_DUMP command, informs the master whether it should send these events by executing the newly added COM_BINLOG_DUMP_OPTIONS_EXT server command: case COM_BINLOG_DUMP_OPTIONS_EXT: thd->binlog_dump_flags_ext= packet[0]; my_ok(thd); break; Note. We add this new command and don't use COM_BINLOG_DUMP to avoid possible conflicts with MySQL/Sun. 6. How master executes the request ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ case COM_BINLOG_DUMP: { ... flags= uint2korr(packet + 4); ... mysql_binlog_send(thd, ..., flags); ... } void mysql_binlog_send(THD* thd, ..., ushort flags) { ... Log_event::read_log_event(&log, packet, ...); ... if ((*packet)[EVENT_TYPE_OFFSET + 1] != ANNOTATE_ROWS_EVENT || flags & BINLOG_SEND_ANNOTATE_ROWS_EVENT) { my_net_write(net, packet->ptr(), packet->length()); } ... } 7. How slave SQL thread processes Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The slave processes each recieved event by "applying" it, i.e. by calling the Log_event::apply_event() function which in turn calls the virtual do_apply_event() member specific for each type of the event. int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev = next_event(rli); ... apply_event_and_update_pos(ev, ...); if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } int apply_event_and_update_pos(Log_event *ev, ...) { ... ev->apply_event(...); ... } int Log_event::apply_event(...) { return do_apply_event(...); } What does it mean to "apply" an Annotate_rows event? It means to set current thd query to that of the described by the event, i.e. to the query which caused the subsequent Rows events (see "How Master writes Annotate_rows events to the binary log" to follow what happens further when the subsequent Rows events are applied): int Annotate_rows_log_event::do_apply_event(...) { thd->set_query(m_query_txt, m_query_len); } NOTE. I am not sure, but possibly current values of thd->query and thd->query_length should be saved before calling set_query() and to be restored on the Annotate_rows_log_event object deletion. Is it really needed ? After calling this do_apply_event() function we may not delete the Annotate_rows_log_event object immediatedly (see exec_relay_log_event() above) because thd->query now points to the string inside this object. We may keep the pointer to this object in the Relay_log_info: class Relay_log_info { public: ... void set_annotate_event(Annotate_rows_log_event*); Annotate_rows_log_event* get_annotate_event(); void free_annotate_event(); ... private: Annotate_rows_log_event* m_annotate_event; }; The saved Annotate_rows object should be deleted when all corresponding Rows events will be processed: int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev= next_event(rli); ... apply_event_and_update_pos(ev, ...); if (rli->get_annotate_event() && is_last_rows_event(ev)) rli->free_annotate_event(); else if (ev->get_type_code() == ANNOTATE_ROWS_EVENT) rli->set_annotate_event((Annotate_rows_log_event*) ev); else if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } where bool is_last_rows_event(Log_event* ev) { Log_event_type type= ev->get_type_code(); if (IS_ROWS_EVENT_TYPE(type)) { Rows_log_event* rows= (Rows_log_event*)ev; return rows->get_flags(Rows_log_event::STMT_END_F); } return 0; } #define IS_ROWS_EVENT_TYPE(type) ((type) == WRITE_ROWS_EVENT || \ (type) == UPDATE_ROWS_EVENT || \ (type) == DELETE_ROWS_EVENT) 8. General remarks ~~~~~~~~~~~~~~~~~~ Kristian noticed that introducing new log event type should be coordinated somehow with MySQL/Sun: Kristian: The numeric code for this event must be assigned carefully. It should be coordinated with MySQL/Sun, otherwise we can get into a situation where MySQL uses the same numeric code for one event that MariaDB uses for ANNOTATE_ROWS_EVENT, which would make merging the two impossible. Alex: I reserved about 20 numbers not to have possible conflicts with MySQL. Kristian: Still, I think it would be appropriate to send a polite email to internals(a)lists.mysql.com about this and suggesting to reserve the event number. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Progress (by Alexi): Store in binlog text of statements that caused RBR events (47)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Store in binlog text of statements that caused RBR events CREATION DATE..: Sat, 15 Aug 2009, 23:48 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Knielsen, Serg CATEGORY.......: Server-Sprint TASK ID........: 47 (http://askmonty.org/worklog/?tid=47) VERSION........: Server-9.x STATUS.........: Code-Review PRIORITY.......: 60 WORKED HOURS...: 67 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 35 PROGRESS NOTES: -=-=(Alexi - Thu, 24 Jun 2010, 09:47)=-=- Making rpl- and binlog-tests stable w.r.t. adding new binlog events. Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Knielsen - Mon, 21 Jun 2010, 08:32)=-=- Final review. Assist with some problems applying the patch. Worked 1 hour and estimate 0 hours remain (original estimate increased by 1 hour). -=-=(Guest - Thu, 17 Jun 2010, 00:38)=-=- Dependency deleted: 39 no longer depends on 47 -=-=(Knielsen - Mon, 07 Jun 2010, 07:13)=-=- Help debug some test failures seen in Buildbot. Worked 6 hours and estimate 0 hours remain (original estimate increased by 6 hours). -=-=(Knielsen - Mon, 31 May 2010, 06:49)=-=- Help Alexi debug+fix some test problems in the patch. Worked 4 hours and estimate 0 hours remain (original estimate unchanged). -=-=(Knielsen - Tue, 25 May 2010, 08:29)=-=- Help debug strange problem in mysqlbinlog.test. Worked 1 hour and estimate 4 hours remain (original estimate unchanged). -=-=(Knielsen - Mon, 17 May 2010, 08:45)=-=- Merge with latest trunk and run Buildbot tests. Worked 1 hour and estimate 5 hours remain (original estimate unchanged). -=-=(Knielsen - Wed, 05 May 2010, 13:53)=-=- Review of fixes to first review done. No new issues found. Worked 2 hours and estimate 6 hours remain (original estimate unchanged). -=-=(Knielsen - Fri, 23 Apr 2010, 12:51)=-=- Status updated. --- /tmp/wklog.47.old.28747 2010-04-23 12:51:36.000000000 +0000 +++ /tmp/wklog.47.new.28747 2010-04-23 12:51:36.000000000 +0000 @@ -1 +1 @@ -In-Progress +Code-Review -=-=(Knielsen - Tue, 06 Apr 2010, 15:26)=-=- Code review (mailed to maria-developers@). Worked 7 hours and estimate 8 hours remain (original estimate unchanged). ------------------------------------------------------------ -=-=(View All Progress Notes, 36 total)=-=- http://askmonty.org/worklog/index.pl?tid=47&nolimit=1 DESCRIPTION: Store in binlog (and show in mysqlbinlog output) texts of statements that caused RBR events This is needed for (list from Monty): - Easier to understand why updates happened - Would make it easier to find out where in application things went wrong (as you can search for exact strings) - Allow one to filter things based on comments in the statement. The cost of this can be that the binlog will be approximately 2x in size (especially insert of big blob's would be a bit painful), so this should be an optional feature. HIGH-LEVEL SPECIFICATION: Content ~~~~~~~ 1. Annotate_rows_log_event 2. Server option: --binlog-annotate-rows-events 3. Server option: --replicate-annotate-rows-events 4. mysqlbinlog option: --print-annotate-rows-events 5. mysqlbinlog output 1. Annotate_rows_log_event [ ANNOTATE_ROWS_EVENT ] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Describes the query which caused the corresponding rows events. Has empty post-header and contains the query text in its data part. Example: ************************ ANNOTATE_ROWS_EVENT ************************ 00000220 | B6 A0 2C 4B | time_when = 1261215926 00000224 | 33 | event_type = 51 00000225 | 64 00 00 00 | server_id = 100 00000229 | 36 00 00 00 | event_len = 54 0000022D | 56 02 00 00 | log_pos = 00000256 00000231 | 00 00 | flags = <none> ------------------------ 00000233 | 49 4E 53 45 | query = "INSERT INTO t1 VALUES (1), (2), (3)" 00000237 | 52 54 20 49 | 0000023B | 4E 54 4F 20 | 0000023F | 74 31 20 56 | 00000243 | 41 4C 55 45 | 00000247 | 53 20 28 31 | 0000024B | 29 2C 20 28 | 0000024F | 32 29 2C 20 | 00000253 | 28 33 29 | ************************ In binary log, Annotate_rows event follows the (possible) 'BEGIN' Query event and precedes the first of Table map events which accompany the corresponding rows events. (See example in the "mysqlbinlog output" section below.) 2. Server option: --binlog-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the master to write Annotate_rows events to the binary log. * Variable Name: binlog_annotate_rows_events * Scope: Global & Session * Access Type: Dynamic * Data Type: bool * Default Value: OFF NOTE. Session values allows to annotate only some selected statements: ... SET SESSION binlog_annotate_rows_events=ON; ... statements to be annotated ... SET SESSION binlog_annotate_rows_events=OFF; ... statements not to be annotated ... 3. Server option: --replicate-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the slave to reproduce Annotate_rows events recieved from the master in its own binary log (sensible only in pair with log-slave-updates option). * Variable Name: replicate_annotate_rows_events * Scope: Global * Access Type: Read only * Data Type: bool * Default Value: OFF NOTE. Why do we additionally need this 'replicate' option? Why not to make the slave to reproduce this events when its binlog-annotate-rows-events global value is ON? Well, because, for example, we may want to configure the slave which should reproduce Annotate_rows events but has global binlog-annotate-rows-events = OFF meaning this to be the default value for the client threads (see also "How slave treats replicate-annotate-rows-events option" in LLD part). 4. mysqlbinlog option: --print-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ With this option, mysqlbinlog prints the content of Annotate_rows events (if the binary log does contain them). Without this option (i.e. by default), mysqlbinlog skips Annotate_rows events. 5. mysqlbinlog output ~~~~~~~~~~~~~~~~~~~~~ With --print-annotate-rows-events, mysqlbinlog outputs Annotate_rows events in a form like this: ... # at 1646 #091219 12:45:26 server id 100 end_log_pos 1714 Query thread_id=1 exec_time=0 error_code=0 SET TIMESTAMP=1261215926/*!*/; BEGIN /*!*/; # at 1714 # at 1812 # at 1853 # at 1894 # at 1938 #091219 12:45:26 server id 100 end_log_pos 1812 Query: `DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.a=t2.a AND t2.a=t3.a` #091219 12:45:26 server id 100 end_log_pos 1853 Table_map: `test`.`t1` mapped to number 16 #091219 12:45:26 server id 100 end_log_pos 1894 Table_map: `test`.`t2` mapped to number 17 #091219 12:45:26 server id 100 end_log_pos 1938 Delete_rows: table id 16 #091219 12:45:26 server id 100 end_log_pos 1982 Delete_rows: table id 17 flags: STMT_END_F ... LOW-LEVEL DESIGN: Content ~~~~~~~ 1. Annotate_rows event number 2. Outline of Annotate_rows event behavior 3. How Master writes Annotate_rows events to the binary log 4. How slave treats replicate-annotate-rows-events option 5. How slave IO thread requests Annotate_rows events 6. How master executes the request 7. How slave SQL thread processes Annotate_rows events 8. General remarks 1. Annotate_rows event number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To avoid possible event numbers conflict with MySQL/Sun, we leave a gap between the last MySQL event number and the Annotate_rows event number: enum Log_event_type { ... INCIDENT_EVENT= 26, // New MySQL event numbers are to be added here MYSQL_EVENTS_END, MARIA_EVENTS_BEGIN= 51, // New Maria event numbers start from here ANNOTATE_ROWS_EVENT= 51, ENUM_END_EVENT }; together with the corresponding extension of 'post_header_len' array in the Format description event. (This extension does not affect the compatibility of the binary log). Here is how Format description event looks like with this extension: ************************ FORMAT_DESCRIPTION_EVENT ************************ 00000004 | A1 A0 2C 4B | time_when = 1261215905 00000008 | 0F | event_type = 15 00000009 | 64 00 00 00 | server_id = 100 0000000D | 7F 00 00 00 | event_len = 127 00000011 | 83 00 00 00 | log_pos = 00000083 00000015 | 01 00 | flags = LOG_EVENT_BINLOG_IN_USE_F ------------------------ 00000017 | 04 00 | binlog_ver = 4 00000019 | 35 2E 32 2E | server_ver = 5.2.0-MariaDB-alpha-debug-log ..... ... 0000004B | A1 A0 2C 4B | time_created = 1261215905 0000004F | 13 | common_header_len = 19 ------------------------ post_header_len ------------------------ 00000050 | 38 | 56 - START_EVENT_V3 [1] ..... ... 00000069 | 02 | 2 - INCIDENT_EVENT [26] 0000006A | 00 | 0 - RESERVED [27] ..... ... 00000081 | 00 | 0 - RESERVED [50] 00000082 | 00 | 0 - ANNOTATE_ROWS_EVENT [51] ************************ 2. Outline of Annotate_rows event behavior ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each Annotate_rows_log_event object has two private members describing the corresponding query: char *m_query_txt; uint m_query_len; When the object is created for writing to a binary log, this query is taken from 'thd' (for short, below we omit the 'Annotate_rows_log_event::' prefix as well as other implementation details): Annotate_rows_log_event(THD *thd) { m_query_txt = thd->query(); m_query_len = thd->query_length(); } When the object is read from a binary log, the query is taken from the buffer containing the binary log representation of the event (this buffer is allocated in Log_event object from which all Log events are derived): Annotate_rows_log_event(char *buf, uint event_len, Format_description_log_event *desc) { m_query_len = event_len - desc->common_header_len; m_query_txt = buf + desc->common_header_len; } The events are written to the binary log by the Log_event::write() member which calls virtual write_data_header() and write_data_body() members ("data header" and "post header" are synonym in replication terminology). In our case, data header is empty and data body is just the query: bool write_data_body(IO_CACHE *file) { return my_b_safe_write(file, (uchar*) m_query_txt, m_query_len); } Printing the event is just printing the query: void Annotate_rows_log_event::print(FILE *file, PRINT_EVENT_INFO *pinfo) { my_b_printf(&pinfo->head_cache, "\tQuery: `%s`\n", m_query_txt); } 3. How Master writes Annotate_rows events to the binary log ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The event is written to the binary log just before the group of Table_map events which precede corresponding Rows events (one query may generate several Table map events in the binary log, but the corresponding Annotate_rows event must be written only once before the first Table map event; hence the boolean variable 'with_annotate' below): int write_locked_table_maps(THD *thd) { ... bool with_annotate= thd->variables.binlog_annotate_rows_events; ... for (uint i= 0; i < ... <number of tables> ...; ++i) { ... thd->binlog_write_table_map(table, ..., with_annotate); with_annotate= 0; // write Annotate_event not more than once ... } ... } int THD::binlog_write_table_map(TABLE *table, ..., bool with_annotate) { ... Table_map_log_event the_event(...); ... if (with_annotate) { Annotate_rows_log_event anno(this); mysql_bin_log.write(&anno); } mysql_bin_log.write(&the_event); ... } 4. How slave treats replicate-annotate-rows-events option ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The replicate-annotate-rows-events option is treated just as the session value of the binlog_annotate_rows_events variable for the slave IO and SQL threads. This setting is done during initialization of these threads: pthread_handler_t handle_slave_io(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_IO); ... } pthread_handler_t handle_slave_sql(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_SQL); ... } int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type) { ... thd->variables.binlog_annotate_rows_events= opt_replicate_annotate_rows_events; ... } 5. How slave IO thread requests Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the replicate-annotate-rows-events option is not set on a slave, there is no need for master to send Annotate_rows events to this slave. The slave (or mysqlbinlog in remote case), before requesting binlog dump via the COM_BINLOG_DUMP command, informs the master whether it should send these events by executing the newly added COM_BINLOG_DUMP_OPTIONS_EXT server command: case COM_BINLOG_DUMP_OPTIONS_EXT: thd->binlog_dump_flags_ext= packet[0]; my_ok(thd); break; Note. We add this new command and don't use COM_BINLOG_DUMP to avoid possible conflicts with MySQL/Sun. 6. How master executes the request ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ case COM_BINLOG_DUMP: { ... flags= uint2korr(packet + 4); ... mysql_binlog_send(thd, ..., flags); ... } void mysql_binlog_send(THD* thd, ..., ushort flags) { ... Log_event::read_log_event(&log, packet, ...); ... if ((*packet)[EVENT_TYPE_OFFSET + 1] != ANNOTATE_ROWS_EVENT || flags & BINLOG_SEND_ANNOTATE_ROWS_EVENT) { my_net_write(net, packet->ptr(), packet->length()); } ... } 7. How slave SQL thread processes Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The slave processes each recieved event by "applying" it, i.e. by calling the Log_event::apply_event() function which in turn calls the virtual do_apply_event() member specific for each type of the event. int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev = next_event(rli); ... apply_event_and_update_pos(ev, ...); if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } int apply_event_and_update_pos(Log_event *ev, ...) { ... ev->apply_event(...); ... } int Log_event::apply_event(...) { return do_apply_event(...); } What does it mean to "apply" an Annotate_rows event? It means to set current thd query to that of the described by the event, i.e. to the query which caused the subsequent Rows events (see "How Master writes Annotate_rows events to the binary log" to follow what happens further when the subsequent Rows events are applied): int Annotate_rows_log_event::do_apply_event(...) { thd->set_query(m_query_txt, m_query_len); } NOTE. I am not sure, but possibly current values of thd->query and thd->query_length should be saved before calling set_query() and to be restored on the Annotate_rows_log_event object deletion. Is it really needed ? After calling this do_apply_event() function we may not delete the Annotate_rows_log_event object immediatedly (see exec_relay_log_event() above) because thd->query now points to the string inside this object. We may keep the pointer to this object in the Relay_log_info: class Relay_log_info { public: ... void set_annotate_event(Annotate_rows_log_event*); Annotate_rows_log_event* get_annotate_event(); void free_annotate_event(); ... private: Annotate_rows_log_event* m_annotate_event; }; The saved Annotate_rows object should be deleted when all corresponding Rows events will be processed: int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev= next_event(rli); ... apply_event_and_update_pos(ev, ...); if (rli->get_annotate_event() && is_last_rows_event(ev)) rli->free_annotate_event(); else if (ev->get_type_code() == ANNOTATE_ROWS_EVENT) rli->set_annotate_event((Annotate_rows_log_event*) ev); else if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } where bool is_last_rows_event(Log_event* ev) { Log_event_type type= ev->get_type_code(); if (IS_ROWS_EVENT_TYPE(type)) { Rows_log_event* rows= (Rows_log_event*)ev; return rows->get_flags(Rows_log_event::STMT_END_F); } return 0; } #define IS_ROWS_EVENT_TYPE(type) ((type) == WRITE_ROWS_EVENT || \ (type) == UPDATE_ROWS_EVENT || \ (type) == DELETE_ROWS_EVENT) 8. General remarks ~~~~~~~~~~~~~~~~~~ Kristian noticed that introducing new log event type should be coordinated somehow with MySQL/Sun: Kristian: The numeric code for this event must be assigned carefully. It should be coordinated with MySQL/Sun, otherwise we can get into a situation where MySQL uses the same numeric code for one event that MariaDB uses for ANNOTATE_ROWS_EVENT, which would make merging the two impossible. Alex: I reserved about 20 numbers not to have possible conflicts with MySQL. Kristian: Still, I think it would be appropriate to send a polite email to internals(a)lists.mysql.com about this and suggesting to reserve the event number. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Progress (by Alexi): Store in binlog text of statements that caused RBR events (47)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Store in binlog text of statements that caused RBR events CREATION DATE..: Sat, 15 Aug 2009, 23:48 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Knielsen, Serg CATEGORY.......: Server-Sprint TASK ID........: 47 (http://askmonty.org/worklog/?tid=47) VERSION........: Server-9.x STATUS.........: Code-Review PRIORITY.......: 60 WORKED HOURS...: 67 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 35 PROGRESS NOTES: -=-=(Alexi - Thu, 24 Jun 2010, 09:47)=-=- Making rpl- and binlog-tests stable w.r.t. adding new binlog events. Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Knielsen - Mon, 21 Jun 2010, 08:32)=-=- Final review. Assist with some problems applying the patch. Worked 1 hour and estimate 0 hours remain (original estimate increased by 1 hour). -=-=(Guest - Thu, 17 Jun 2010, 00:38)=-=- Dependency deleted: 39 no longer depends on 47 -=-=(Knielsen - Mon, 07 Jun 2010, 07:13)=-=- Help debug some test failures seen in Buildbot. Worked 6 hours and estimate 0 hours remain (original estimate increased by 6 hours). -=-=(Knielsen - Mon, 31 May 2010, 06:49)=-=- Help Alexi debug+fix some test problems in the patch. Worked 4 hours and estimate 0 hours remain (original estimate unchanged). -=-=(Knielsen - Tue, 25 May 2010, 08:29)=-=- Help debug strange problem in mysqlbinlog.test. Worked 1 hour and estimate 4 hours remain (original estimate unchanged). -=-=(Knielsen - Mon, 17 May 2010, 08:45)=-=- Merge with latest trunk and run Buildbot tests. Worked 1 hour and estimate 5 hours remain (original estimate unchanged). -=-=(Knielsen - Wed, 05 May 2010, 13:53)=-=- Review of fixes to first review done. No new issues found. Worked 2 hours and estimate 6 hours remain (original estimate unchanged). -=-=(Knielsen - Fri, 23 Apr 2010, 12:51)=-=- Status updated. --- /tmp/wklog.47.old.28747 2010-04-23 12:51:36.000000000 +0000 +++ /tmp/wklog.47.new.28747 2010-04-23 12:51:36.000000000 +0000 @@ -1 +1 @@ -In-Progress +Code-Review -=-=(Knielsen - Tue, 06 Apr 2010, 15:26)=-=- Code review (mailed to maria-developers@). Worked 7 hours and estimate 8 hours remain (original estimate unchanged). ------------------------------------------------------------ -=-=(View All Progress Notes, 36 total)=-=- http://askmonty.org/worklog/index.pl?tid=47&nolimit=1 DESCRIPTION: Store in binlog (and show in mysqlbinlog output) texts of statements that caused RBR events This is needed for (list from Monty): - Easier to understand why updates happened - Would make it easier to find out where in application things went wrong (as you can search for exact strings) - Allow one to filter things based on comments in the statement. The cost of this can be that the binlog will be approximately 2x in size (especially insert of big blob's would be a bit painful), so this should be an optional feature. HIGH-LEVEL SPECIFICATION: Content ~~~~~~~ 1. Annotate_rows_log_event 2. Server option: --binlog-annotate-rows-events 3. Server option: --replicate-annotate-rows-events 4. mysqlbinlog option: --print-annotate-rows-events 5. mysqlbinlog output 1. Annotate_rows_log_event [ ANNOTATE_ROWS_EVENT ] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Describes the query which caused the corresponding rows events. Has empty post-header and contains the query text in its data part. Example: ************************ ANNOTATE_ROWS_EVENT ************************ 00000220 | B6 A0 2C 4B | time_when = 1261215926 00000224 | 33 | event_type = 51 00000225 | 64 00 00 00 | server_id = 100 00000229 | 36 00 00 00 | event_len = 54 0000022D | 56 02 00 00 | log_pos = 00000256 00000231 | 00 00 | flags = <none> ------------------------ 00000233 | 49 4E 53 45 | query = "INSERT INTO t1 VALUES (1), (2), (3)" 00000237 | 52 54 20 49 | 0000023B | 4E 54 4F 20 | 0000023F | 74 31 20 56 | 00000243 | 41 4C 55 45 | 00000247 | 53 20 28 31 | 0000024B | 29 2C 20 28 | 0000024F | 32 29 2C 20 | 00000253 | 28 33 29 | ************************ In binary log, Annotate_rows event follows the (possible) 'BEGIN' Query event and precedes the first of Table map events which accompany the corresponding rows events. (See example in the "mysqlbinlog output" section below.) 2. Server option: --binlog-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the master to write Annotate_rows events to the binary log. * Variable Name: binlog_annotate_rows_events * Scope: Global & Session * Access Type: Dynamic * Data Type: bool * Default Value: OFF NOTE. Session values allows to annotate only some selected statements: ... SET SESSION binlog_annotate_rows_events=ON; ... statements to be annotated ... SET SESSION binlog_annotate_rows_events=OFF; ... statements not to be annotated ... 3. Server option: --replicate-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the slave to reproduce Annotate_rows events recieved from the master in its own binary log (sensible only in pair with log-slave-updates option). * Variable Name: replicate_annotate_rows_events * Scope: Global * Access Type: Read only * Data Type: bool * Default Value: OFF NOTE. Why do we additionally need this 'replicate' option? Why not to make the slave to reproduce this events when its binlog-annotate-rows-events global value is ON? Well, because, for example, we may want to configure the slave which should reproduce Annotate_rows events but has global binlog-annotate-rows-events = OFF meaning this to be the default value for the client threads (see also "How slave treats replicate-annotate-rows-events option" in LLD part). 4. mysqlbinlog option: --print-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ With this option, mysqlbinlog prints the content of Annotate_rows events (if the binary log does contain them). Without this option (i.e. by default), mysqlbinlog skips Annotate_rows events. 5. mysqlbinlog output ~~~~~~~~~~~~~~~~~~~~~ With --print-annotate-rows-events, mysqlbinlog outputs Annotate_rows events in a form like this: ... # at 1646 #091219 12:45:26 server id 100 end_log_pos 1714 Query thread_id=1 exec_time=0 error_code=0 SET TIMESTAMP=1261215926/*!*/; BEGIN /*!*/; # at 1714 # at 1812 # at 1853 # at 1894 # at 1938 #091219 12:45:26 server id 100 end_log_pos 1812 Query: `DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.a=t2.a AND t2.a=t3.a` #091219 12:45:26 server id 100 end_log_pos 1853 Table_map: `test`.`t1` mapped to number 16 #091219 12:45:26 server id 100 end_log_pos 1894 Table_map: `test`.`t2` mapped to number 17 #091219 12:45:26 server id 100 end_log_pos 1938 Delete_rows: table id 16 #091219 12:45:26 server id 100 end_log_pos 1982 Delete_rows: table id 17 flags: STMT_END_F ... LOW-LEVEL DESIGN: Content ~~~~~~~ 1. Annotate_rows event number 2. Outline of Annotate_rows event behavior 3. How Master writes Annotate_rows events to the binary log 4. How slave treats replicate-annotate-rows-events option 5. How slave IO thread requests Annotate_rows events 6. How master executes the request 7. How slave SQL thread processes Annotate_rows events 8. General remarks 1. Annotate_rows event number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To avoid possible event numbers conflict with MySQL/Sun, we leave a gap between the last MySQL event number and the Annotate_rows event number: enum Log_event_type { ... INCIDENT_EVENT= 26, // New MySQL event numbers are to be added here MYSQL_EVENTS_END, MARIA_EVENTS_BEGIN= 51, // New Maria event numbers start from here ANNOTATE_ROWS_EVENT= 51, ENUM_END_EVENT }; together with the corresponding extension of 'post_header_len' array in the Format description event. (This extension does not affect the compatibility of the binary log). Here is how Format description event looks like with this extension: ************************ FORMAT_DESCRIPTION_EVENT ************************ 00000004 | A1 A0 2C 4B | time_when = 1261215905 00000008 | 0F | event_type = 15 00000009 | 64 00 00 00 | server_id = 100 0000000D | 7F 00 00 00 | event_len = 127 00000011 | 83 00 00 00 | log_pos = 00000083 00000015 | 01 00 | flags = LOG_EVENT_BINLOG_IN_USE_F ------------------------ 00000017 | 04 00 | binlog_ver = 4 00000019 | 35 2E 32 2E | server_ver = 5.2.0-MariaDB-alpha-debug-log ..... ... 0000004B | A1 A0 2C 4B | time_created = 1261215905 0000004F | 13 | common_header_len = 19 ------------------------ post_header_len ------------------------ 00000050 | 38 | 56 - START_EVENT_V3 [1] ..... ... 00000069 | 02 | 2 - INCIDENT_EVENT [26] 0000006A | 00 | 0 - RESERVED [27] ..... ... 00000081 | 00 | 0 - RESERVED [50] 00000082 | 00 | 0 - ANNOTATE_ROWS_EVENT [51] ************************ 2. Outline of Annotate_rows event behavior ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each Annotate_rows_log_event object has two private members describing the corresponding query: char *m_query_txt; uint m_query_len; When the object is created for writing to a binary log, this query is taken from 'thd' (for short, below we omit the 'Annotate_rows_log_event::' prefix as well as other implementation details): Annotate_rows_log_event(THD *thd) { m_query_txt = thd->query(); m_query_len = thd->query_length(); } When the object is read from a binary log, the query is taken from the buffer containing the binary log representation of the event (this buffer is allocated in Log_event object from which all Log events are derived): Annotate_rows_log_event(char *buf, uint event_len, Format_description_log_event *desc) { m_query_len = event_len - desc->common_header_len; m_query_txt = buf + desc->common_header_len; } The events are written to the binary log by the Log_event::write() member which calls virtual write_data_header() and write_data_body() members ("data header" and "post header" are synonym in replication terminology). In our case, data header is empty and data body is just the query: bool write_data_body(IO_CACHE *file) { return my_b_safe_write(file, (uchar*) m_query_txt, m_query_len); } Printing the event is just printing the query: void Annotate_rows_log_event::print(FILE *file, PRINT_EVENT_INFO *pinfo) { my_b_printf(&pinfo->head_cache, "\tQuery: `%s`\n", m_query_txt); } 3. How Master writes Annotate_rows events to the binary log ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The event is written to the binary log just before the group of Table_map events which precede corresponding Rows events (one query may generate several Table map events in the binary log, but the corresponding Annotate_rows event must be written only once before the first Table map event; hence the boolean variable 'with_annotate' below): int write_locked_table_maps(THD *thd) { ... bool with_annotate= thd->variables.binlog_annotate_rows_events; ... for (uint i= 0; i < ... <number of tables> ...; ++i) { ... thd->binlog_write_table_map(table, ..., with_annotate); with_annotate= 0; // write Annotate_event not more than once ... } ... } int THD::binlog_write_table_map(TABLE *table, ..., bool with_annotate) { ... Table_map_log_event the_event(...); ... if (with_annotate) { Annotate_rows_log_event anno(this); mysql_bin_log.write(&anno); } mysql_bin_log.write(&the_event); ... } 4. How slave treats replicate-annotate-rows-events option ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The replicate-annotate-rows-events option is treated just as the session value of the binlog_annotate_rows_events variable for the slave IO and SQL threads. This setting is done during initialization of these threads: pthread_handler_t handle_slave_io(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_IO); ... } pthread_handler_t handle_slave_sql(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_SQL); ... } int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type) { ... thd->variables.binlog_annotate_rows_events= opt_replicate_annotate_rows_events; ... } 5. How slave IO thread requests Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the replicate-annotate-rows-events option is not set on a slave, there is no need for master to send Annotate_rows events to this slave. The slave (or mysqlbinlog in remote case), before requesting binlog dump via the COM_BINLOG_DUMP command, informs the master whether it should send these events by executing the newly added COM_BINLOG_DUMP_OPTIONS_EXT server command: case COM_BINLOG_DUMP_OPTIONS_EXT: thd->binlog_dump_flags_ext= packet[0]; my_ok(thd); break; Note. We add this new command and don't use COM_BINLOG_DUMP to avoid possible conflicts with MySQL/Sun. 6. How master executes the request ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ case COM_BINLOG_DUMP: { ... flags= uint2korr(packet + 4); ... mysql_binlog_send(thd, ..., flags); ... } void mysql_binlog_send(THD* thd, ..., ushort flags) { ... Log_event::read_log_event(&log, packet, ...); ... if ((*packet)[EVENT_TYPE_OFFSET + 1] != ANNOTATE_ROWS_EVENT || flags & BINLOG_SEND_ANNOTATE_ROWS_EVENT) { my_net_write(net, packet->ptr(), packet->length()); } ... } 7. How slave SQL thread processes Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The slave processes each recieved event by "applying" it, i.e. by calling the Log_event::apply_event() function which in turn calls the virtual do_apply_event() member specific for each type of the event. int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev = next_event(rli); ... apply_event_and_update_pos(ev, ...); if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } int apply_event_and_update_pos(Log_event *ev, ...) { ... ev->apply_event(...); ... } int Log_event::apply_event(...) { return do_apply_event(...); } What does it mean to "apply" an Annotate_rows event? It means to set current thd query to that of the described by the event, i.e. to the query which caused the subsequent Rows events (see "How Master writes Annotate_rows events to the binary log" to follow what happens further when the subsequent Rows events are applied): int Annotate_rows_log_event::do_apply_event(...) { thd->set_query(m_query_txt, m_query_len); } NOTE. I am not sure, but possibly current values of thd->query and thd->query_length should be saved before calling set_query() and to be restored on the Annotate_rows_log_event object deletion. Is it really needed ? After calling this do_apply_event() function we may not delete the Annotate_rows_log_event object immediatedly (see exec_relay_log_event() above) because thd->query now points to the string inside this object. We may keep the pointer to this object in the Relay_log_info: class Relay_log_info { public: ... void set_annotate_event(Annotate_rows_log_event*); Annotate_rows_log_event* get_annotate_event(); void free_annotate_event(); ... private: Annotate_rows_log_event* m_annotate_event; }; The saved Annotate_rows object should be deleted when all corresponding Rows events will be processed: int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev= next_event(rli); ... apply_event_and_update_pos(ev, ...); if (rli->get_annotate_event() && is_last_rows_event(ev)) rli->free_annotate_event(); else if (ev->get_type_code() == ANNOTATE_ROWS_EVENT) rli->set_annotate_event((Annotate_rows_log_event*) ev); else if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } where bool is_last_rows_event(Log_event* ev) { Log_event_type type= ev->get_type_code(); if (IS_ROWS_EVENT_TYPE(type)) { Rows_log_event* rows= (Rows_log_event*)ev; return rows->get_flags(Rows_log_event::STMT_END_F); } return 0; } #define IS_ROWS_EVENT_TYPE(type) ((type) == WRITE_ROWS_EVENT || \ (type) == UPDATE_ROWS_EVENT || \ (type) == DELETE_ROWS_EVENT) 8. General remarks ~~~~~~~~~~~~~~~~~~ Kristian noticed that introducing new log event type should be coordinated somehow with MySQL/Sun: Kristian: The numeric code for this event must be assigned carefully. It should be coordinated with MySQL/Sun, otherwise we can get into a situation where MySQL uses the same numeric code for one event that MariaDB uses for ANNOTATE_ROWS_EVENT, which would make merging the two impossible. Alex: I reserved about 20 numbers not to have possible conflicts with MySQL. Kristian: Still, I think it would be appropriate to send a polite email to internals(a)lists.mysql.com about this and suggesting to reserve the event number. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

1 0

[Maria-developers] Progress (by Alexi): Store in binlog text of statements that caused RBR events (47)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Store in binlog text of statements that caused RBR events CREATION DATE..: Sat, 15 Aug 2009, 23:48 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: Knielsen, Serg CATEGORY.......: Server-Sprint TASK ID........: 47 (http://askmonty.org/worklog/?tid=47) VERSION........: Server-9.x STATUS.........: Code-Review PRIORITY.......: 60 WORKED HOURS...: 67 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 35 PROGRESS NOTES: -=-=(Alexi - Thu, 24 Jun 2010, 09:47)=-=- Making rpl- and binlog-tests stable w.r.t. adding new binlog events. Worked 25 hours and estimate 0 hours remain (original estimate increased by 25 hours). -=-=(Knielsen - Mon, 21 Jun 2010, 08:32)=-=- Final review. Assist with some problems applying the patch. Worked 1 hour and estimate 0 hours remain (original estimate increased by 1 hour). -=-=(Guest - Thu, 17 Jun 2010, 00:38)=-=- Dependency deleted: 39 no longer depends on 47 -=-=(Knielsen - Mon, 07 Jun 2010, 07:13)=-=- Help debug some test failures seen in Buildbot. Worked 6 hours and estimate 0 hours remain (original estimate increased by 6 hours). -=-=(Knielsen - Mon, 31 May 2010, 06:49)=-=- Help Alexi debug+fix some test problems in the patch. Worked 4 hours and estimate 0 hours remain (original estimate unchanged). -=-=(Knielsen - Tue, 25 May 2010, 08:29)=-=- Help debug strange problem in mysqlbinlog.test. Worked 1 hour and estimate 4 hours remain (original estimate unchanged). -=-=(Knielsen - Mon, 17 May 2010, 08:45)=-=- Merge with latest trunk and run Buildbot tests. Worked 1 hour and estimate 5 hours remain (original estimate unchanged). -=-=(Knielsen - Wed, 05 May 2010, 13:53)=-=- Review of fixes to first review done. No new issues found. Worked 2 hours and estimate 6 hours remain (original estimate unchanged). -=-=(Knielsen - Fri, 23 Apr 2010, 12:51)=-=- Status updated. --- /tmp/wklog.47.old.28747 2010-04-23 12:51:36.000000000 +0000 +++ /tmp/wklog.47.new.28747 2010-04-23 12:51:36.000000000 +0000 @@ -1 +1 @@ -In-Progress +Code-Review -=-=(Knielsen - Tue, 06 Apr 2010, 15:26)=-=- Code review (mailed to maria-developers@). Worked 7 hours and estimate 8 hours remain (original estimate unchanged). ------------------------------------------------------------ -=-=(View All Progress Notes, 36 total)=-=- http://askmonty.org/worklog/index.pl?tid=47&nolimit=1 DESCRIPTION: Store in binlog (and show in mysqlbinlog output) texts of statements that caused RBR events This is needed for (list from Monty): - Easier to understand why updates happened - Would make it easier to find out where in application things went wrong (as you can search for exact strings) - Allow one to filter things based on comments in the statement. The cost of this can be that the binlog will be approximately 2x in size (especially insert of big blob's would be a bit painful), so this should be an optional feature. HIGH-LEVEL SPECIFICATION: Content ~~~~~~~ 1. Annotate_rows_log_event 2. Server option: --binlog-annotate-rows-events 3. Server option: --replicate-annotate-rows-events 4. mysqlbinlog option: --print-annotate-rows-events 5. mysqlbinlog output 1. Annotate_rows_log_event [ ANNOTATE_ROWS_EVENT ] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Describes the query which caused the corresponding rows events. Has empty post-header and contains the query text in its data part. Example: ************************ ANNOTATE_ROWS_EVENT ************************ 00000220 | B6 A0 2C 4B | time_when = 1261215926 00000224 | 33 | event_type = 51 00000225 | 64 00 00 00 | server_id = 100 00000229 | 36 00 00 00 | event_len = 54 0000022D | 56 02 00 00 | log_pos = 00000256 00000231 | 00 00 | flags = <none> ------------------------ 00000233 | 49 4E 53 45 | query = "INSERT INTO t1 VALUES (1), (2), (3)" 00000237 | 52 54 20 49 | 0000023B | 4E 54 4F 20 | 0000023F | 74 31 20 56 | 00000243 | 41 4C 55 45 | 00000247 | 53 20 28 31 | 0000024B | 29 2C 20 28 | 0000024F | 32 29 2C 20 | 00000253 | 28 33 29 | ************************ In binary log, Annotate_rows event follows the (possible) 'BEGIN' Query event and precedes the first of Table map events which accompany the corresponding rows events. (See example in the "mysqlbinlog output" section below.) 2. Server option: --binlog-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the master to write Annotate_rows events to the binary log. * Variable Name: binlog_annotate_rows_events * Scope: Global & Session * Access Type: Dynamic * Data Type: bool * Default Value: OFF NOTE. Session values allows to annotate only some selected statements: ... SET SESSION binlog_annotate_rows_events=ON; ... statements to be annotated ... SET SESSION binlog_annotate_rows_events=OFF; ... statements not to be annotated ... 3. Server option: --replicate-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Tells the slave to reproduce Annotate_rows events recieved from the master in its own binary log (sensible only in pair with log-slave-updates option). * Variable Name: replicate_annotate_rows_events * Scope: Global * Access Type: Read only * Data Type: bool * Default Value: OFF NOTE. Why do we additionally need this 'replicate' option? Why not to make the slave to reproduce this events when its binlog-annotate-rows-events global value is ON? Well, because, for example, we may want to configure the slave which should reproduce Annotate_rows events but has global binlog-annotate-rows-events = OFF meaning this to be the default value for the client threads (see also "How slave treats replicate-annotate-rows-events option" in LLD part). 4. mysqlbinlog option: --print-annotate-rows-events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ With this option, mysqlbinlog prints the content of Annotate_rows events (if the binary log does contain them). Without this option (i.e. by default), mysqlbinlog skips Annotate_rows events. 5. mysqlbinlog output ~~~~~~~~~~~~~~~~~~~~~ With --print-annotate-rows-events, mysqlbinlog outputs Annotate_rows events in a form like this: ... # at 1646 #091219 12:45:26 server id 100 end_log_pos 1714 Query thread_id=1 exec_time=0 error_code=0 SET TIMESTAMP=1261215926/*!*/; BEGIN /*!*/; # at 1714 # at 1812 # at 1853 # at 1894 # at 1938 #091219 12:45:26 server id 100 end_log_pos 1812 Query: `DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.a=t2.a AND t2.a=t3.a` #091219 12:45:26 server id 100 end_log_pos 1853 Table_map: `test`.`t1` mapped to number 16 #091219 12:45:26 server id 100 end_log_pos 1894 Table_map: `test`.`t2` mapped to number 17 #091219 12:45:26 server id 100 end_log_pos 1938 Delete_rows: table id 16 #091219 12:45:26 server id 100 end_log_pos 1982 Delete_rows: table id 17 flags: STMT_END_F ... LOW-LEVEL DESIGN: Content ~~~~~~~ 1. Annotate_rows event number 2. Outline of Annotate_rows event behavior 3. How Master writes Annotate_rows events to the binary log 4. How slave treats replicate-annotate-rows-events option 5. How slave IO thread requests Annotate_rows events 6. How master executes the request 7. How slave SQL thread processes Annotate_rows events 8. General remarks 1. Annotate_rows event number ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To avoid possible event numbers conflict with MySQL/Sun, we leave a gap between the last MySQL event number and the Annotate_rows event number: enum Log_event_type { ... INCIDENT_EVENT= 26, // New MySQL event numbers are to be added here MYSQL_EVENTS_END, MARIA_EVENTS_BEGIN= 51, // New Maria event numbers start from here ANNOTATE_ROWS_EVENT= 51, ENUM_END_EVENT }; together with the corresponding extension of 'post_header_len' array in the Format description event. (This extension does not affect the compatibility of the binary log). Here is how Format description event looks like with this extension: ************************ FORMAT_DESCRIPTION_EVENT ************************ 00000004 | A1 A0 2C 4B | time_when = 1261215905 00000008 | 0F | event_type = 15 00000009 | 64 00 00 00 | server_id = 100 0000000D | 7F 00 00 00 | event_len = 127 00000011 | 83 00 00 00 | log_pos = 00000083 00000015 | 01 00 | flags = LOG_EVENT_BINLOG_IN_USE_F ------------------------ 00000017 | 04 00 | binlog_ver = 4 00000019 | 35 2E 32 2E | server_ver = 5.2.0-MariaDB-alpha-debug-log ..... ... 0000004B | A1 A0 2C 4B | time_created = 1261215905 0000004F | 13 | common_header_len = 19 ------------------------ post_header_len ------------------------ 00000050 | 38 | 56 - START_EVENT_V3 [1] ..... ... 00000069 | 02 | 2 - INCIDENT_EVENT [26] 0000006A | 00 | 0 - RESERVED [27] ..... ... 00000081 | 00 | 0 - RESERVED [50] 00000082 | 00 | 0 - ANNOTATE_ROWS_EVENT [51] ************************ 2. Outline of Annotate_rows event behavior ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Each Annotate_rows_log_event object has two private members describing the corresponding query: char *m_query_txt; uint m_query_len; When the object is created for writing to a binary log, this query is taken from 'thd' (for short, below we omit the 'Annotate_rows_log_event::' prefix as well as other implementation details): Annotate_rows_log_event(THD *thd) { m_query_txt = thd->query(); m_query_len = thd->query_length(); } When the object is read from a binary log, the query is taken from the buffer containing the binary log representation of the event (this buffer is allocated in Log_event object from which all Log events are derived): Annotate_rows_log_event(char *buf, uint event_len, Format_description_log_event *desc) { m_query_len = event_len - desc->common_header_len; m_query_txt = buf + desc->common_header_len; } The events are written to the binary log by the Log_event::write() member which calls virtual write_data_header() and write_data_body() members ("data header" and "post header" are synonym in replication terminology). In our case, data header is empty and data body is just the query: bool write_data_body(IO_CACHE *file) { return my_b_safe_write(file, (uchar*) m_query_txt, m_query_len); } Printing the event is just printing the query: void Annotate_rows_log_event::print(FILE *file, PRINT_EVENT_INFO *pinfo) { my_b_printf(&pinfo->head_cache, "\tQuery: `%s`\n", m_query_txt); } 3. How Master writes Annotate_rows events to the binary log ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The event is written to the binary log just before the group of Table_map events which precede corresponding Rows events (one query may generate several Table map events in the binary log, but the corresponding Annotate_rows event must be written only once before the first Table map event; hence the boolean variable 'with_annotate' below): int write_locked_table_maps(THD *thd) { ... bool with_annotate= thd->variables.binlog_annotate_rows_events; ... for (uint i= 0; i < ... <number of tables> ...; ++i) { ... thd->binlog_write_table_map(table, ..., with_annotate); with_annotate= 0; // write Annotate_event not more than once ... } ... } int THD::binlog_write_table_map(TABLE *table, ..., bool with_annotate) { ... Table_map_log_event the_event(...); ... if (with_annotate) { Annotate_rows_log_event anno(this); mysql_bin_log.write(&anno); } mysql_bin_log.write(&the_event); ... } 4. How slave treats replicate-annotate-rows-events option ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The replicate-annotate-rows-events option is treated just as the session value of the binlog_annotate_rows_events variable for the slave IO and SQL threads. This setting is done during initialization of these threads: pthread_handler_t handle_slave_io(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_IO); ... } pthread_handler_t handle_slave_sql(void *arg) { THD *thd= new THD; ... init_slave_thread(thd, SLAVE_THD_SQL); ... } int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type) { ... thd->variables.binlog_annotate_rows_events= opt_replicate_annotate_rows_events; ... } 5. How slave IO thread requests Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ If the replicate-annotate-rows-events option is not set on a slave, there is no need for master to send Annotate_rows events to this slave. The slave (or mysqlbinlog in remote case), before requesting binlog dump via the COM_BINLOG_DUMP command, informs the master whether it should send these events by executing the newly added COM_BINLOG_DUMP_OPTIONS_EXT server command: case COM_BINLOG_DUMP_OPTIONS_EXT: thd->binlog_dump_flags_ext= packet[0]; my_ok(thd); break; Note. We add this new command and don't use COM_BINLOG_DUMP to avoid possible conflicts with MySQL/Sun. 6. How master executes the request ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ case COM_BINLOG_DUMP: { ... flags= uint2korr(packet + 4); ... mysql_binlog_send(thd, ..., flags); ... } void mysql_binlog_send(THD* thd, ..., ushort flags) { ... Log_event::read_log_event(&log, packet, ...); ... if ((*packet)[EVENT_TYPE_OFFSET + 1] != ANNOTATE_ROWS_EVENT || flags & BINLOG_SEND_ANNOTATE_ROWS_EVENT) { my_net_write(net, packet->ptr(), packet->length()); } ... } 7. How slave SQL thread processes Annotate_rows events ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The slave processes each recieved event by "applying" it, i.e. by calling the Log_event::apply_event() function which in turn calls the virtual do_apply_event() member specific for each type of the event. int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev = next_event(rli); ... apply_event_and_update_pos(ev, ...); if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } int apply_event_and_update_pos(Log_event *ev, ...) { ... ev->apply_event(...); ... } int Log_event::apply_event(...) { return do_apply_event(...); } What does it mean to "apply" an Annotate_rows event? It means to set current thd query to that of the described by the event, i.e. to the query which caused the subsequent Rows events (see "How Master writes Annotate_rows events to the binary log" to follow what happens further when the subsequent Rows events are applied): int Annotate_rows_log_event::do_apply_event(...) { thd->set_query(m_query_txt, m_query_len); } NOTE. I am not sure, but possibly current values of thd->query and thd->query_length should be saved before calling set_query() and to be restored on the Annotate_rows_log_event object deletion. Is it really needed ? After calling this do_apply_event() function we may not delete the Annotate_rows_log_event object immediatedly (see exec_relay_log_event() above) because thd->query now points to the string inside this object. We may keep the pointer to this object in the Relay_log_info: class Relay_log_info { public: ... void set_annotate_event(Annotate_rows_log_event*); Annotate_rows_log_event* get_annotate_event(); void free_annotate_event(); ... private: Annotate_rows_log_event* m_annotate_event; }; The saved Annotate_rows object should be deleted when all corresponding Rows events will be processed: int exec_relay_log_event(THD* thd, Relay_log_info* rli) { ... Log_event *ev= next_event(rli); ... apply_event_and_update_pos(ev, ...); if (rli->get_annotate_event() && is_last_rows_event(ev)) rli->free_annotate_event(); else if (ev->get_type_code() == ANNOTATE_ROWS_EVENT) rli->set_annotate_event((Annotate_rows_log_event*) ev); else if (ev->get_type_code() != FORMAT_DESCRIPTION_EVENT) delete ev; ... } where bool is_last_rows_event(Log_event* ev) { Log_event_type type= ev->get_type_code(); if (IS_ROWS_EVENT_TYPE(type)) { Rows_log_event* rows= (Rows_log_event*)ev; return rows->get_flags(Rows_log_event::STMT_END_F); } return 0; } #define IS_ROWS_EVENT_TYPE(type) ((type) == WRITE_ROWS_EVENT || \ (type) == UPDATE_ROWS_EVENT || \ (type) == DELETE_ROWS_EVENT) 8. General remarks ~~~~~~~~~~~~~~~~~~ Kristian noticed that introducing new log event type should be coordinated somehow with MySQL/Sun: Kristian: The numeric code for this event must be assigned carefully. It should be coordinated with MySQL/Sun, otherwise we can get into a situation where MySQL uses the same numeric code for one event that MariaDB uses for ANNOTATE_ROWS_EVENT, which would make merging the two impossible. Alex: I reserved about 20 numbers not to have possible conflicts with MySQL. Kristian: Still, I think it would be appropriate to send a polite email to internals(a)lists.mysql.com about this and suggesting to reserve the event number. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] XtraDB and FederatedX in the Windows zip file
by Bo Thorsen 24 Jun '10

24 Jun '10

Hi all, For the next release of 5.2, we wanted to be sure that it comes with the proper engines. In previous releases it had to be built manually to include XtraDB, and didn't have FederatedX at all. I spent some time looking at the plugin loading code, which turned out to be irrelevant. Because a standard build of the zip file now actually has FederatedX and XtraDB in it. So the Windows code is good to go :-) Bo Thorsen. Monty Program AB. -- MariaDB: MySQL replacement Community developed. Feature enhanced. Backward compatible.

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[Maria-developers] Updated (by Sanja): Subquery optimization: Avoid recalculating subquery if external fields values found in subquery cache (66)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Subquery optimization: Avoid recalculating subquery if external fields values found in subquery cache CREATION DATE..: Wed, 25 Nov 2009, 22:25 SUPERVISOR.....: Monty IMPLEMENTOR....: Sanja COPIES TO......: CATEGORY.......: Client-Sprint TASK ID........: 66 (http://askmonty.org/worklog/?tid=66) VERSION........: 9.x STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Sanja - Thu, 24 Jun 2010, 06:01)=-=- Low Level Design modified. --- /tmp/wklog.66.old.19228 2010-06-24 06:01:35.000000000 +0000 +++ /tmp/wklog.66.new.19228 2010-06-24 06:01:35.000000000 +0000 @@ -1,10 +1,10 @@ -* Target version: base on mysql-5.2 code +* Target version: base on mysql-5.3 code All items on which subquery depend could be collected in -st_select_lex::mark_as_dependent (direct of indirect reference?) +st_select_lex::register_dependency_item (indirect reference) Temporary table index should be created by all fields except result field -(TMP_TABLE_PARAM::keyinfo). +(TABLE::add_tmp_key). How to fill the temptable ------------------------- @@ -49,7 +49,8 @@ if (res || !sjm->in_equality->val_int()) DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS); -The code in this WL will use the same approach +The code in this WL will use the same approach except eqality which will be +created according to field type (some types do not need it) Extracting the value of the subquery predicate ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -58,3 +59,11 @@ temporary table's field and then subquery_predicate->val_int() will invoke $I->val_int(), subquery_predicate->val_str() will invoke $I->val_str() and so forth. + +Caching the subquery in Item tree +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +We use Item::transform to put caching Item (Item_cache_wrapper) before the +subquery (Item_subquery* or Item_in_optimizer). For this we add new transformer +method ::cache_insert_transformer. + -=-=(Guest - Sun, 13 Jun 2010, 16:51)=-=- Dependency deleted: 91 no longer depends on 66 -=-=(Igor - Wed, 10 Mar 2010, 21:29)=-=- High Level Description modified. --- /tmp/wklog.66.old.32188 2010-03-10 21:29:16.000000000 +0000 +++ /tmp/wklog.66.new.32188 2010-03-10 21:29:16.000000000 +0000 @@ -1,3 +1,10 @@ +The goal of this task is to optimize evaluation of subqueries and subquery +predicates by storing the results of a correlated subquery together with +correlation parameters in a cache and reusing those results for the same sets of +parameters. + +Here's what is to be done in this task in more details: + Collect all outer items/references (left part of the subquiery and outer references inside the subquery) in key string. Compare the string (which represents certain value set of the references) against values in hash table and -=-=(Igor - Wed, 10 Mar 2010, 21:13)=-=- Dependency created: 91 now depends on 66 -=-=(Igor - Wed, 10 Mar 2010, 21:12)=-=- Category updated. --- /tmp/wklog.66.old.31558 2010-03-10 21:12:50.000000000 +0000 +++ /tmp/wklog.66.new.31558 2010-03-10 21:12:50.000000000 +0000 @@ -1 +1 @@ -Server-BackLog +Client-Sprint -=-=(Igor - Wed, 10 Mar 2010, 21:12)=-=- Version updated. --- /tmp/wklog.66.old.31558 2010-03-10 21:12:50.000000000 +0000 +++ /tmp/wklog.66.new.31558 2010-03-10 21:12:50.000000000 +0000 @@ -1 +1 @@ -Server-5.3 +9.x -=-=(Monty - Fri, 29 Jan 2010, 19:07)=-=- Version updated. --- /tmp/wklog.66.old.5893 2010-01-29 19:07:10.000000000 +0200 +++ /tmp/wklog.66.new.5893 2010-01-29 19:07:10.000000000 +0200 @@ -1 +1 @@ -Server-5.2 +Server-5.3 -=-=(Psergey - Wed, 20 Jan 2010, 14:50)=-=- High-Level Specification modified. --- /tmp/wklog.66.old.26873 2010-01-20 14:50:41.000000000 +0200 +++ /tmp/wklog.66.new.26873 2010-01-20 14:50:41.000000000 +0200 @@ -4,7 +4,6 @@ To check/discuss: ----------------- -* Do we put subquery cache on all levels of subqueries or on highest level only * Will there be any means to measure subquery cache hit rate? * MySQL-6.0 has a one-element predicate result cache. It is called "left expression cache", grep for left_expr_cache in sql/item_subselect.* @@ -41,7 +40,12 @@ - subquery_item_result is 'bool' for subquery predicates, and is of some scalar or ROW(scalar1,...scalarN) type for scalar-context subquery. -We dont support cases when outer_expr or correlation_references are blobs. +We don't support cases when outer_expr or correlation_references are blobs. + +All subquery predicates are cached. That is, if one subquery predicate is +located within another, both of them will have caches (one option to reduce +cache memory usage was to use cache only for the upper-most select. we decided +against it). 2. Data structure used for the cache ------------------------------------ -=-=(Psergey - Wed, 20 Jan 2010, 13:07)=-=- High-Level Specification modified. --- /tmp/wklog.66.old.17649 2010-01-20 13:07:07.000000000 +0200 +++ /tmp/wklog.66.new.17649 2010-01-20 13:07:07.000000000 +0200 @@ -3,7 +3,13 @@ To check/discuss: - To put subquery cache on all levels of subqueries or on highest level only. +----------------- +* Do we put subquery cache on all levels of subqueries or on highest level only +* Will there be any means to measure subquery cache hit rate? +* MySQL-6.0 has a one-element predicate result cache. It is called "left + expression cache", grep for left_expr_cache in sql/item_subselect.* + When this WL is merged with 6.0's optimizations, these two caches will + need to be unified somehow. <contents> -=-=(Psergey - Mon, 18 Jan 2010, 16:40)=-=- Low Level Design modified. --- /tmp/wklog.66.old.24899 2010-01-18 16:40:16.000000000 +0200 +++ /tmp/wklog.66.new.24899 2010-01-18 16:40:16.000000000 +0200 @@ -1,3 +1,5 @@ +* Target version: base on mysql-5.2 code + All items on which subquery depend could be collected in st_select_lex::mark_as_dependent (direct of indirect reference?) ------------------------------------------------------------ -=-=(View All Progress Notes, 19 total)=-=- http://askmonty.org/worklog/index.pl?tid=66&nolimit=1 DESCRIPTION: The goal of this task is to optimize evaluation of subqueries and subquery predicates by storing the results of a correlated subquery together with correlation parameters in a cache and reusing those results for the same sets of parameters. Here's what is to be done in this task in more details: Collect all outer items/references (left part of the subquiery and outer references inside the subquery) in key string. Compare the string (which represents certain value set of the references) against values in hash table and return cached result of subquery if the reference values combination has already been used. For example in the following subquery: (L1, L2) IN (SELECT A, B FROM T WHERE T.F1>OTER_FIELD) set of references to look into the subquery cache is (L1, L2, OTER_FIELD). The subquery cache should be implemented as simple LRU connected to the subquery. Size of the subquery cache (in number of results (but maybe in used memory amount)) is limited by session variable (query parameter?). HIGH-LEVEL SPECIFICATION: Attach subquery cache to each Item_subquery. Interface should allow to use hash or temporary table inside. To check/discuss: ----------------- * Will there be any means to measure subquery cache hit rate? * MySQL-6.0 has a one-element predicate result cache. It is called "left expression cache", grep for left_expr_cache in sql/item_subselect.* When this WL is merged with 6.0's optimizations, these two caches will need to be unified somehow. <contents> 1. Scope of the task 2. Data structure used for the cache 3. Cache size 4. Interplay with other subquery optimizations 5. User interface </contents> 1. Scope of the task -------------------- This WL should handle all subquery predicates, i.e. it should handle these cases: outer_expr IN (SELECT correlated_select) outer_expr $CMP$ ALL/ANY (SELECT correlated_select) EXISTS (SELECT correlated_select) scalar-context subquery: (SELECT correlated_select) The cache will maintain (outer_expr, correlation_references)-> subquery_item_result mapping, where - correlation_references is a list of tablename.column_name that are referred from the correlated_select but tablename is a table that is ouside the subquery. - subquery_item_result is 'bool' for subquery predicates, and is of some scalar or ROW(scalar1,...scalarN) type for scalar-context subquery. We don't support cases when outer_expr or correlation_references are blobs. All subquery predicates are cached. That is, if one subquery predicate is located within another, both of them will have caches (one option to reduce cache memory usage was to use cache only for the upper-most select. we decided against it). 2. Data structure used for the cache ------------------------------------ There are two data structures available in the codebase that will allow fast equality lookups: 1. HASH (mysys/hash.c) tables 2. Temporary tables (the ones that are used for e.g. GROUP BY) None of them has any support for element eviction on overflow (using LRU or some other policy). Query cache and MyISAM/Maria's key/page cache ought to support some eviction mechanism, but code-wise it is not readily reusable, one will need to factor it out (or copy it). We choose to use #2, and not to have any eviction policy. See subsequent sections for details and reasoning behind the decision. 3. Cache size ------------- Typically, a cache has some maximum size and a policy which is used to select a cache entry for removal when the cache becomes full (e.g. find and remove the least [recently] used entry) For this WL entry we will use a cache of infinite size. The reasoning behind this is that: - is is easy to do: we have temporary tables that can grow to arbitrarily large size while still providing the same insert/lookup interface. - it suits us: unless the subquery is resolved with one index lookup, hitting the cache would be many times cheaper than re-running the subquery, so cache is worth having. 4. Interplay with other subquery optimizations ---------------------------------------------- * This WL entry should not care about IN->EXISTS transformation: caching for IN subquery and result of its conversion to EXISTS would work in the same way. * This optimization is orthogonal to <=>ANY -> MIN/MAX rewrite (it will work/be useful irrespectively of whether the rewrite has been performed or not) * TODO: compare this with materialization for uncorrelated IN-subqueries. Is this basically the same? A: no, it is not: - IN-Materialization has to perform full materialization before it can do the first subquery evaluation. This WL's code has almost no startup costs. - This optimization has temp.table of (corr_reference, predicate_value), while IN-materialization will have (corr_reference) only. 5. User interface ----------------- * There will be an @@optimizer_switch flag to turn this optimization on and off (TODO: name of the flag?) * TODO: how do we show this in EXPLAIN [EXTENDED]? The most easiest is to print something in the warning text of EXPLAIN EXTEDED that would indicate use of cache. * temporary table sizing (max size for heap table, whether to use MyISAM or Maria) will be controlled with common temp.table control variables. LOW-LEVEL DESIGN: * Target version: base on mysql-5.3 code All items on which subquery depend could be collected in st_select_lex::register_dependency_item (indirect reference) Temporary table index should be created by all fields except result field (TABLE::add_tmp_key). How to fill the temptable ------------------------- Can reuse approach from SJ-Materialization. Its code is in end_sj_materialize() and is supposed to be quite trivial. How to make lookups into temptable ---------------------------------- We'll reuse approach used by SJ-Materialization in 6.0. Setup process ~~~~~~~~~~~~~ Setup is performed in the same way as in setup_sj_materialization(), see the code that starts these lines: /* Create/initialize everything we will need to index lookups into the temptable. */ and ends at this line: Remove the injected semi-join IN-equalities from join_tab conds. This <questionable> We'll also need to check equalities, i.e. do an equivalent of this: if (!(sjm->in_equality= create_subq_in_equalities(thd, sjm, emb_sj_nest->sj_subq_pred))) DBUG_RETURN(TRUE); /* purecov: inspected */ Question: or perhaps that is not necessarry? </questionable> Doing the lookup ~~~~~~~~~~~~~~~~ SJ-Materialization does lookup in sub_select_sjm(), with this code: /* Do index lookup in the materialized table */ if ((res= join_read_key2(join_tab, sjm->table, sjm->tab_ref)) == 1) DBUG_RETURN(NESTED_LOOP_ERROR); /* purecov: inspected */ if (res || !sjm->in_equality->val_int()) DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS); The code in this WL will use the same approach except eqality which will be created according to field type (some types do not need it) Extracting the value of the subquery predicate ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The goal of making the lookup is to get the value of subquery predicate. This is done by creating an Item_field $I which refers to appropriate temporary table's field and then subquery_predicate->val_int() will invoke $I->val_int(), subquery_predicate->val_str() will invoke $I->val_str() and so forth. Caching the subquery in Item tree ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We use Item::transform to put caching Item (Item_cache_wrapper) before the subquery (Item_subquery* or Item_in_optimizer). For this we add new transformer method ::cache_insert_transformer. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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[Maria-developers] Updated (by Sanja): Subquery optimization: Avoid recalculating subquery if external fields values found in subquery cache (66)
by worklog-noreply＠askmonty.org 24 Jun '10

24 Jun '10

----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Subquery optimization: Avoid recalculating subquery if external fields values found in subquery cache CREATION DATE..: Wed, 25 Nov 2009, 22:25 SUPERVISOR.....: Monty IMPLEMENTOR....: Sanja COPIES TO......: CATEGORY.......: Client-Sprint TASK ID........: 66 (http://askmonty.org/worklog/?tid=66) VERSION........: 9.x STATUS.........: Assigned PRIORITY.......: 60 WORKED HOURS...: 0 ESTIMATE.......: 0 (hours remain) ORIG. ESTIMATE.: 0 PROGRESS NOTES: -=-=(Sanja - Thu, 24 Jun 2010, 06:01)=-=- Low Level Design modified. --- /tmp/wklog.66.old.19228 2010-06-24 06:01:35.000000000 +0000 +++ /tmp/wklog.66.new.19228 2010-06-24 06:01:35.000000000 +0000 @@ -1,10 +1,10 @@ -* Target version: base on mysql-5.2 code +* Target version: base on mysql-5.3 code All items on which subquery depend could be collected in -st_select_lex::mark_as_dependent (direct of indirect reference?) +st_select_lex::register_dependency_item (indirect reference) Temporary table index should be created by all fields except result field -(TMP_TABLE_PARAM::keyinfo). +(TABLE::add_tmp_key). How to fill the temptable ------------------------- @@ -49,7 +49,8 @@ if (res || !sjm->in_equality->val_int()) DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS); -The code in this WL will use the same approach +The code in this WL will use the same approach except eqality which will be +created according to field type (some types do not need it) Extracting the value of the subquery predicate ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -58,3 +59,11 @@ temporary table's field and then subquery_predicate->val_int() will invoke $I->val_int(), subquery_predicate->val_str() will invoke $I->val_str() and so forth. + +Caching the subquery in Item tree +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +We use Item::transform to put caching Item (Item_cache_wrapper) before the +subquery (Item_subquery* or Item_in_optimizer). For this we add new transformer +method ::cache_insert_transformer. + -=-=(Guest - Sun, 13 Jun 2010, 16:51)=-=- Dependency deleted: 91 no longer depends on 66 -=-=(Igor - Wed, 10 Mar 2010, 21:29)=-=- High Level Description modified. --- /tmp/wklog.66.old.32188 2010-03-10 21:29:16.000000000 +0000 +++ /tmp/wklog.66.new.32188 2010-03-10 21:29:16.000000000 +0000 @@ -1,3 +1,10 @@ +The goal of this task is to optimize evaluation of subqueries and subquery +predicates by storing the results of a correlated subquery together with +correlation parameters in a cache and reusing those results for the same sets of +parameters. + +Here's what is to be done in this task in more details: + Collect all outer items/references (left part of the subquiery and outer references inside the subquery) in key string. Compare the string (which represents certain value set of the references) against values in hash table and -=-=(Igor - Wed, 10 Mar 2010, 21:13)=-=- Dependency created: 91 now depends on 66 -=-=(Igor - Wed, 10 Mar 2010, 21:12)=-=- Category updated. --- /tmp/wklog.66.old.31558 2010-03-10 21:12:50.000000000 +0000 +++ /tmp/wklog.66.new.31558 2010-03-10 21:12:50.000000000 +0000 @@ -1 +1 @@ -Server-BackLog +Client-Sprint -=-=(Igor - Wed, 10 Mar 2010, 21:12)=-=- Version updated. --- /tmp/wklog.66.old.31558 2010-03-10 21:12:50.000000000 +0000 +++ /tmp/wklog.66.new.31558 2010-03-10 21:12:50.000000000 +0000 @@ -1 +1 @@ -Server-5.3 +9.x -=-=(Monty - Fri, 29 Jan 2010, 19:07)=-=- Version updated. --- /tmp/wklog.66.old.5893 2010-01-29 19:07:10.000000000 +0200 +++ /tmp/wklog.66.new.5893 2010-01-29 19:07:10.000000000 +0200 @@ -1 +1 @@ -Server-5.2 +Server-5.3 -=-=(Psergey - Wed, 20 Jan 2010, 14:50)=-=- High-Level Specification modified. --- /tmp/wklog.66.old.26873 2010-01-20 14:50:41.000000000 +0200 +++ /tmp/wklog.66.new.26873 2010-01-20 14:50:41.000000000 +0200 @@ -4,7 +4,6 @@ To check/discuss: ----------------- -* Do we put subquery cache on all levels of subqueries or on highest level only * Will there be any means to measure subquery cache hit rate? * MySQL-6.0 has a one-element predicate result cache. It is called "left expression cache", grep for left_expr_cache in sql/item_subselect.* @@ -41,7 +40,12 @@ - subquery_item_result is 'bool' for subquery predicates, and is of some scalar or ROW(scalar1,...scalarN) type for scalar-context subquery. -We dont support cases when outer_expr or correlation_references are blobs. +We don't support cases when outer_expr or correlation_references are blobs. + +All subquery predicates are cached. That is, if one subquery predicate is +located within another, both of them will have caches (one option to reduce +cache memory usage was to use cache only for the upper-most select. we decided +against it). 2. Data structure used for the cache ------------------------------------ -=-=(Psergey - Wed, 20 Jan 2010, 13:07)=-=- High-Level Specification modified. --- /tmp/wklog.66.old.17649 2010-01-20 13:07:07.000000000 +0200 +++ /tmp/wklog.66.new.17649 2010-01-20 13:07:07.000000000 +0200 @@ -3,7 +3,13 @@ To check/discuss: - To put subquery cache on all levels of subqueries or on highest level only. +----------------- +* Do we put subquery cache on all levels of subqueries or on highest level only +* Will there be any means to measure subquery cache hit rate? +* MySQL-6.0 has a one-element predicate result cache. It is called "left + expression cache", grep for left_expr_cache in sql/item_subselect.* + When this WL is merged with 6.0's optimizations, these two caches will + need to be unified somehow. <contents> -=-=(Psergey - Mon, 18 Jan 2010, 16:40)=-=- Low Level Design modified. --- /tmp/wklog.66.old.24899 2010-01-18 16:40:16.000000000 +0200 +++ /tmp/wklog.66.new.24899 2010-01-18 16:40:16.000000000 +0200 @@ -1,3 +1,5 @@ +* Target version: base on mysql-5.2 code + All items on which subquery depend could be collected in st_select_lex::mark_as_dependent (direct of indirect reference?) ------------------------------------------------------------ -=-=(View All Progress Notes, 19 total)=-=- http://askmonty.org/worklog/index.pl?tid=66&nolimit=1 DESCRIPTION: The goal of this task is to optimize evaluation of subqueries and subquery predicates by storing the results of a correlated subquery together with correlation parameters in a cache and reusing those results for the same sets of parameters. Here's what is to be done in this task in more details: Collect all outer items/references (left part of the subquiery and outer references inside the subquery) in key string. Compare the string (which represents certain value set of the references) against values in hash table and return cached result of subquery if the reference values combination has already been used. For example in the following subquery: (L1, L2) IN (SELECT A, B FROM T WHERE T.F1>OTER_FIELD) set of references to look into the subquery cache is (L1, L2, OTER_FIELD). The subquery cache should be implemented as simple LRU connected to the subquery. Size of the subquery cache (in number of results (but maybe in used memory amount)) is limited by session variable (query parameter?). HIGH-LEVEL SPECIFICATION: Attach subquery cache to each Item_subquery. Interface should allow to use hash or temporary table inside. To check/discuss: ----------------- * Will there be any means to measure subquery cache hit rate? * MySQL-6.0 has a one-element predicate result cache. It is called "left expression cache", grep for left_expr_cache in sql/item_subselect.* When this WL is merged with 6.0's optimizations, these two caches will need to be unified somehow. <contents> 1. Scope of the task 2. Data structure used for the cache 3. Cache size 4. Interplay with other subquery optimizations 5. User interface </contents> 1. Scope of the task -------------------- This WL should handle all subquery predicates, i.e. it should handle these cases: outer_expr IN (SELECT correlated_select) outer_expr $CMP$ ALL/ANY (SELECT correlated_select) EXISTS (SELECT correlated_select) scalar-context subquery: (SELECT correlated_select) The cache will maintain (outer_expr, correlation_references)-> subquery_item_result mapping, where - correlation_references is a list of tablename.column_name that are referred from the correlated_select but tablename is a table that is ouside the subquery. - subquery_item_result is 'bool' for subquery predicates, and is of some scalar or ROW(scalar1,...scalarN) type for scalar-context subquery. We don't support cases when outer_expr or correlation_references are blobs. All subquery predicates are cached. That is, if one subquery predicate is located within another, both of them will have caches (one option to reduce cache memory usage was to use cache only for the upper-most select. we decided against it). 2. Data structure used for the cache ------------------------------------ There are two data structures available in the codebase that will allow fast equality lookups: 1. HASH (mysys/hash.c) tables 2. Temporary tables (the ones that are used for e.g. GROUP BY) None of them has any support for element eviction on overflow (using LRU or some other policy). Query cache and MyISAM/Maria's key/page cache ought to support some eviction mechanism, but code-wise it is not readily reusable, one will need to factor it out (or copy it). We choose to use #2, and not to have any eviction policy. See subsequent sections for details and reasoning behind the decision. 3. Cache size ------------- Typically, a cache has some maximum size and a policy which is used to select a cache entry for removal when the cache becomes full (e.g. find and remove the least [recently] used entry) For this WL entry we will use a cache of infinite size. The reasoning behind this is that: - is is easy to do: we have temporary tables that can grow to arbitrarily large size while still providing the same insert/lookup interface. - it suits us: unless the subquery is resolved with one index lookup, hitting the cache would be many times cheaper than re-running the subquery, so cache is worth having. 4. Interplay with other subquery optimizations ---------------------------------------------- * This WL entry should not care about IN->EXISTS transformation: caching for IN subquery and result of its conversion to EXISTS would work in the same way. * This optimization is orthogonal to <=>ANY -> MIN/MAX rewrite (it will work/be useful irrespectively of whether the rewrite has been performed or not) * TODO: compare this with materialization for uncorrelated IN-subqueries. Is this basically the same? A: no, it is not: - IN-Materialization has to perform full materialization before it can do the first subquery evaluation. This WL's code has almost no startup costs. - This optimization has temp.table of (corr_reference, predicate_value), while IN-materialization will have (corr_reference) only. 5. User interface ----------------- * There will be an @@optimizer_switch flag to turn this optimization on and off (TODO: name of the flag?) * TODO: how do we show this in EXPLAIN [EXTENDED]? The most easiest is to print something in the warning text of EXPLAIN EXTEDED that would indicate use of cache. * temporary table sizing (max size for heap table, whether to use MyISAM or Maria) will be controlled with common temp.table control variables. LOW-LEVEL DESIGN: * Target version: base on mysql-5.3 code All items on which subquery depend could be collected in st_select_lex::register_dependency_item (indirect reference) Temporary table index should be created by all fields except result field (TABLE::add_tmp_key). How to fill the temptable ------------------------- Can reuse approach from SJ-Materialization. Its code is in end_sj_materialize() and is supposed to be quite trivial. How to make lookups into temptable ---------------------------------- We'll reuse approach used by SJ-Materialization in 6.0. Setup process ~~~~~~~~~~~~~ Setup is performed in the same way as in setup_sj_materialization(), see the code that starts these lines: /* Create/initialize everything we will need to index lookups into the temptable. */ and ends at this line: Remove the injected semi-join IN-equalities from join_tab conds. This <questionable> We'll also need to check equalities, i.e. do an equivalent of this: if (!(sjm->in_equality= create_subq_in_equalities(thd, sjm, emb_sj_nest->sj_subq_pred))) DBUG_RETURN(TRUE); /* purecov: inspected */ Question: or perhaps that is not necessarry? </questionable> Doing the lookup ~~~~~~~~~~~~~~~~ SJ-Materialization does lookup in sub_select_sjm(), with this code: /* Do index lookup in the materialized table */ if ((res= join_read_key2(join_tab, sjm->table, sjm->tab_ref)) == 1) DBUG_RETURN(NESTED_LOOP_ERROR); /* purecov: inspected */ if (res || !sjm->in_equality->val_int()) DBUG_RETURN(NESTED_LOOP_NO_MORE_ROWS); The code in this WL will use the same approach except eqality which will be created according to field type (some types do not need it) Extracting the value of the subquery predicate ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The goal of making the lookup is to get the value of subquery predicate. This is done by creating an Item_field $I which refers to appropriate temporary table's field and then subquery_predicate->val_int() will invoke $I->val_int(), subquery_predicate->val_str() will invoke $I->val_str() and so forth. Caching the subquery in Item tree ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We use Item::transform to put caching Item (Item_cache_wrapper) before the subquery (Item_subquery* or Item_in_optimizer). For this we add new transformer method ::cache_insert_transformer. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)

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