June 2017 - developers - lists.mariadb.org

[Maria-developers] Windows line endings in MariaDB sources again (
by Otto Kekäläinen 24 Jul '19

24 Jul '19

Hello! While trying to release 10.0.26 for Debian and Ubuntu I noticed git chokes again on Windows line endings. As our .gitattributes states that by default git should clean up the line endings, why do we keep getting new Windows line endings in new code? mariadb-10.0$ cat .gitattributes # Set the default behavior, in case people don't have core.autocrlf set. * text=auto ... storage/connect/mysql-test/connect/std_data/*.txt -text mariadb-10.0.26$ find . | xargs file | grep CRLF ./storage/connect/mysql-test/connect/std_data/boyswin.txt: ASCII text, with CRLF line terminators ./storage/connect/mysql-test/connect/std_data/expenses.txt: ASCII text, with CRLF line terminators ./storage/connect/mysql-test/connect/std_data/emp.txt: ASCII text, with CRLF line terminators ./mysql-test/std_data/loaddata7.dat: ASCII text, with CRLF line terminators ./mysql-test/r/loadxml.result: ASCII text, with CRLF, LF line terminators ./mysql-test/r/perror-win.result: ASCII text, with CRLF, LF line terminators ./mysql-test/r/mysql_binary_mode.result: ASCII English text, with CRLF, LF line terminators ./mysql-test/r/func_regexp_pcre.result: UTF-8 Unicode C++ program text, with CRLF, CR, LF line terminators ./pcre/testdata/grepoutputN: ASCII text, with CRLF, CR, LF line terminators ./pcre/testdata/greppatN4: ASCII text, with CRLF line terminators This leads for me to: dpkg-source: info: building mariadb-10.0 using existing ./mariadb-10.0_10.0.26.orig.tar.gz dpkg-source: info: local changes detected, the modified files are: mariadb-10.0/storage/connect/mysql-test/connect/std_data/boyswin.txt mariadb-10.0/storage/connect/mysql-test/connect/std_data/emp.txt mariadb-10.0/storage/connect/mysql-test/connect/std_data/expenses.txt dpkg-source: error: aborting due to unexpected upstream changes, see /tmp/mariadb-10.0_10.0.26-1.diff.Yzwwhw Which means I have to do extra work with importing the upstream sources.. - Otto

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[Maria-developers] 10.2 and merges (e.g. TokuDB)
by Phil Sweeney 28 Aug '18

28 Aug '18

Hi there, It seems 10.2.6 is still shipping with TokuDB from PS 5.6.35-80 (Feb 8th 2017). I can't see a jira issue for a 10.2 merge since 10.2.4. Perhaps intentional to help stabilise 10.2 for release? 10.0.30 also shipped with the same Feb version (in March). 10.1.23 however was released in May and still has this version from Feb, which seems unfortunate, but I know it's because it has to flow through 10.0 first. I see 10.0.31 is due to get TokuDB from PS 5.6.36-82 And that should flow into 10.1.24 soon too. However, 10.2.7 isn't due until July, so by then TokuDB version will be 5 months old in 10.2 I'm waiting on a fairly important row count fix that should appear in the next Percona Server release. When it does, if the current merging strategy continues, do I have to first wait for 10.0.32 to get it in late July, then 10.1.26 in August, then 10.2 after that? Or with 10.0, 10.1 and 10.2 all being supported and needing merges, is there a new strategy on the cards to shorten this lag? Thanks! Phil

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[Maria-developers] MDEV-13118 Wrong results with LOWER and UPPER and subquery
by Alexander Barkov 12 Jul '18

12 Jul '18

Hello Sergei, Please review a patch for MDEV-13118. Thanks!

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Re: [Maria-developers] Mdev-10664 Add statuses about optimistic parallel replication stalls.
by Sachin Setiya 19 Apr '18

19 Apr '18

Hi Kristian! Sorry for late reply , I was on vacations. On Tue, Jan 10, 2017 at 7:31 PM, Kristian Nielsen <knielsen(a)knielsen-hq.org> wrote: > Sachin Setiya <sachin.setiya(a)mariadb.com> writes: > > >> Right, but you still need _some_ way to synchronise multiple threads > > > I used atomic builtins my_atomic_add64_explicit. > > That seems fine (but see comment below). > > > Documentation:- > > > > Slave_DDL_Events:- > > > > Description: Number of DDL statements slave have executed in > > replication channel X. > > Scope: Per Replication Channel > > Data Type: numeric > > Introduced: MariaDB 10.1 > > > > Slave_Non_Transactional_Events:- > > > > Description: Number of Non Transactional "no idea what should be the > > next word " slave have executed in replication channel X. > > Scope: Per Replication Channel > > Data Type: numeric > > Introduced: MariaDB 10.1 > > I checked, the term "event group" is used already multiple places in the > documentation, so I think it can be used here also. An event group can be a > transaction (possibly with multiple transactional DML statements), or a DDL > or non-transactional statement. > > What you are doing is introducing status variables to help understand > optimistic (and aggressive) parallel replication modes. > > In optimistic parallel replication, a non-transactional event group is not > safe to run in parallel with other non-transactional events. So that event > is made to wait for all prior event groups to reach commit state, before > being allowed to execute. However, other transactional events are not > delayed by the non-transactional event group. > > Slave_Non_Transactional_Events counts the occurences of this. > > Then in case of a DDL statement, this can potentially be unsafe to run in > parallel even with other transactional events. So for a DDL, the DDL has to > wait for all prior event groups, _and_ subsequent event groups have to wait > for the DDL. > > Slave_DDL_Events counts these occurences. > > This is what the documentation, and commit messages, should explain, I > think. > > I think the status variables describe the values for > @@default_master_connection?, this should also be explained in the > documentation. > > Why did you decide to put this information into a status variable? > Normally, > slave status is seen in SHOW SLAVE STATUS, which supports showing status > for > a particular connection without using @@default_master_connection. > > Sorry for this , I guess It was a confusion I was looking at Slave_Running this is avaliable in show status as well as show slave status. So I thought for if I want to show some information in SHOW slave status this has to be in show status. And this is wrong. Now we can see non trans events / ddl events in show slave status. Show I remove this vars from Show Status, or it is okay ? > > diff --git a/sql/log_event.h b/sql/log_event.h > > index 90900f6..579607f 100644 > > --- a/sql/log_event.h > > +++ b/sql/log_event.h > > @@ -50,6 +50,7 @@ > > #endif > > > > #include "rpl_gtid.h" > > +#include "my_atomic.h" > > Why include my_atomic.h in the header file, when you only use it in the .cc > file? > Changed. > > > + mysql_mutex_lock(&LOCK_active_mi); > > + if (master_info_index) > > + { > > + mi= master_info_index-> > > + get_master_info(&thd->variables.default_master_connection, > > + Sql_condition::WARN_LEVEL_NOTE); > > + if (mi) > > + tmp= mi->total_ddl_events; > > > + if (mi) > > + tmp= mi->total_non_trans_events; > > Better use an atomic primitive here to read the value. Taking a mutex does > not help synchronise against my_atomic_add64_explicit(). > > Changed. > > + } > > + mysql_mutex_unlock(&LOCK_active_mi); > > + if (mi) > > + *((longlong *)buff)= tmp; > > + else > > + var->type= SHOW_UNDEF; > > + > > + return 0; > > +} > > #endif /* HAVE_REPLICATION */ > > > > static int show_open_tables(THD *thd, SHOW_VAR *var, char *buff, > > > index 9365c06..a474aa5 100644 > > --- a/sql/rpl_mi.h > > +++ b/sql/rpl_mi.h > > @@ -303,6 +303,12 @@ class Master_info : public > Slave_reporting_capability > > > > /* The parallel replication mode. */ > > enum_slave_parallel_mode parallel_mode; > > + > > + /* No of DDL statements */ > > + long total_ddl_events; > > + > > + /* No of non-transactional statements*/ > > + long total_non_trans_events; > > "long" is not the appropriate type here. Certainly not since you are using > my_atomic_add64_explicit(). Use a type that is the same size on all > platforms (and why use a signed type?). > > Changed to uint64. > - Kristian. > Attached a newer version of patch , please review it. -- Regards Sachin

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[Maria-developers] CREATE SEQUENCE is coming
by Michael Widenius 18 Apr '18

18 Apr '18

Hi! For those that are trying to port applications to MariaDB from other databases or need more features than the current AUTO_INCREMENT provides, the following may be of interest: First version of sequence is pushed to bb-10.2-sequence. It should be merged to bb-10.2-compatilbity and then to 10.3 shortly (1-2 weeks). What is working for the moment: CREATE OR REPLACE [TEMPORARY] SEQUENCE [IF NOT EXISTS] name [ INCREMENT [ BY | = ] increment ] [ MINVALUE [=] minvalue | NO MINVALUE ] [ MAXVALUE [=] maxvalue | NO MAXVALUE ] [ START [ WITH | = ] start ] [ CACHE [=] cache ] [ [ NO ] CYCLE ] ENGINE=xxx COMMENT=".." SELECT NEXT VALUE FOR sequence_name; SELECT NEXTVAL(sequence_name); SELECT PREVIOUS VALUE FOR sequence_name; SELECT LASTVAL(sequence_name); SHOW CREATE SEQUENCE sequence_name; SHOW CREATE TABLE sequence_name; CREATE TABLE sequence-structure ... SEQUENCE=1 ALTER TABLE sequence RENAME TO sequence2; RENAME TABLE sequence RENAME TO sequence2; DROP [TEMPORARY] SEQUENCE sequence_name [IF EXISTS] See https://jira.mariadb.org/browse/MDEV-10139 for progress. See commit messages in bb-10.2-sequence for what is still to be done. Some documentation can be found at: https://mariadb.com/kb/en/mariadb/create-sequence/ This will be improved as the work progress. One of the goals with the SEQUENCE implementation is that all old tools, like mysqldump, should work unchanged, while still keeping normal usage of sequence standard compatibly. The make this possible, the sequence is currently implemented as a table with a few exclusive properties. The main disadvantage of having sequence as a table is that it uses the same name space as tables. In other words, you can't have a table and a sequence of the same name. The benefit is that sequences shows up in 'show tables', one can create a sequence also with 'create table' and drop it with 'drop table'. One can select from it as from any other table. This ensures that all old tools that works with tables should work with sequences. The special properties for sequence tables are: - A sequence table has always one row. - When one creates a sequence, either with CREATE TABLE or CREATE SEQUENCE, one row will be inserted. - Normal table options works for CREATE SEQUENCE. One can use ENGINE=xxx, COMMENT=xxx etc. - If one tries to insert into a sequence table, the single row will be updated. This allows mysqldump to work but also gives the additional benefit that one can change all properties of a sequence with a single insert. New applications can of course also use ALTER SEQUENCE. - Updates to the sequence table will change the single row. - Doing a select on the sequence shows the current state of the sequence, except the values that are reserved in the cache. The column 'next_value' shows the next value not reserved by the cache. - Truncate on a sequence table will give an error. - Alter table and rename works on sequences. - If one creates a sequence with INCREMENT 0, then the sequence will use auto_increment_increment and auto_increment_offset for the sequence, just like AUTO_INCREMENT. This allows sequences to work reliable in a master-master environment and with Galera. Internally sequence tables are created as a normal table without rollback (InnoDB, Aria and MySAM supports this) with is wrapped by a sequence engine. This allowed me to create sequences with almost no performance impact for normal tables. (The cost is one 'if' per insert if binary log is enabled). MariaDB 10.3 will support both the ANSI SQL and Oracle syntax for creating and accessing sequences. As ANSI SQL doesn't have an easy access to the last generated value, 103 also supports 'PREVIOUS VALUE FOR sequence_name', like IBM DB2, and LASTVAL(sequence_name) as PostgreSQL. I want to thank Jianwe Zhao from Aliyun for his work on SEQUENCE in AliSQL which gave me ideas and inspiration for this work. I also want to thank Marko Mäkelä for his help in the InnoDB part of the code. There is still a lot of work to fix edge cases, but in the current implementation most major things seams to work... Comments, suggestions or questions? Regards, Monty

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[Maria-developers] a doubt about locks on supremum
by hongxiang jiang 18 Jan '18

18 Jan '18

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[Maria-developers] Add hidden level 2/3 (PSEDUO_HIDDEN_COLUMN / COMPLETELY_HIDDEN_COLUMN) to mariadb
by Sachin Setiya 27 Nov '17

27 Nov '17

Hello Everyone! Currently I am implementing 10177. But I have one doubt I am not sure how to implement a function which will create hidden level 2/3 field for server. Suppose we create a function (say add_hidden_field(.....)) which will add the field to table T. But the issue is where should we call this function in mysql_prepare_create_table / mysql_prepare_alter_table or init_from_binary_frm_image Doing it from init_from_binary_frm_image make sense because this way server and slave frm of table T will be same (We have decided that we wont log hidden level 2/3 field to binlog) , But the issue is optimizer wont be ready to decide whether we require a hidden level 3 field at that time. We can also do it from mysql_prepare_create_table , but I dont think this wont be good idea because at this time optimizer wont be ready plus this will complicate binlog handling. Or may be we should have a function which can modify table object any time. But I am not sure if it is possible/good idea ? What you guys think ? -- Regards Sachin Setiya Software Engineer at MariaDB

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[Maria-developers] Please review MDEV-11292 Item_func_sp::fix_length_and_dec() does not set collation derivation properly
by Alexander Barkov 20 Nov '17

20 Nov '17

Hello Alexey, Please review a patch for MDEV-11292 (for 10.3). Thanks.

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[Maria-developers] RFC: new replication feature "per-engine mysql.gtid_slave pos"
by Kristian Nielsen 11 Jul '17

11 Jul '17

I plan to implement MDEV-12179, per-engine mysql.gtid_slave_pos. Here is a description of the high-level design, as a request for comments and/or suggestion for changes. The purpose of this is to fix a serious performance issue in replication when multiple storage engines are used. Every replicated transaction updates the replication GTID position in table mysql.gtid_slave_pos. There is a large overhead if that table is using another storage engine than the rest of the transaction, as then a cross-engine XA transaction needs to be done. But if more than one storage engine is used on a server, some replicated transactions will necessarily end up being cross-engine. This problem becomes more interesting to fix with the new interest in MyRocks. Though it already exists also for eg. people using MyISAM or TokuDB simultaneously with InnoDB, for example. The basic idea is to create multiple copies of the table, eg. mysql.gtid_slave_pos_innodb and mysql.gtid_slave_pos_myrocks. This way, an InnoDB transaction can update the InnoDB version of the table, and similar for other engines. To enable the feature, the DBA would create extra copies of the table for the engines she wants: CREATE TABLE mysql.gtid_slave_pos_myrocks LIKE mysql.gtid_slave_pos; ALTER TABLE mysql.gtid_slave_pos_myrocks ENGINE=myrocks; The server will look for all tables called mysql.gtid_slave_pos* at startup, as well as on each START SLAVE. This method makes migration from earlier versions simple. MariaDB already has the ability to work with multiple redundant rows in the mysql.gtid_slave_pos table. The column "sub_id" provides a version to identify the most recent entry. So the server just needs to read multiple tables (if present), and pick the newest version amongst all rows. Thus, the new feature is compatible with older versions without any schema changes. I think it is better than automatically creating copies of the table for all engines; it is often the case that an engine (eg. TokuDB) is available in the server binary, but the user does not want any tables created in that engine. This means that no speedup is obtained if the user does not create additional mysql.gtid_slave_pos* tables. (However, things should still work fine, thanks to XA synchronising cross-engine transactions). - Kristian.

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[Maria-developers] Project Progress Report[PHASE-1]
by ANKIT KUMAR 30 Jun '17

30 Jun '17

Hi, I have newly started contributing to opensource projects, so these 3.5 weeks have been really awesome from learning point of view. Everyday I learnt something new, kept experimenting various approaches to a particular problem. I have come a long way as I am about to finish 2 subtasks among 4(4th being optional as it already does what it's expected to). Whole MariaDB community has been really helpful, and special thanks to my Mentor without whom support it wouldn't have been possible. Just recollecting everything I did in this phase- 1. Learnt how bison works, how grammar is written, how actions can be written(w.r.t to extended syntax), how parsing is done, 2. Implemented Extended CREATE USER and GRANT USER syntax. 3. Created tests for the acceptance of newly implemented grammar. 4. Designed in-memory structures that will store value of plugins and perform AND/OR operations as per precedence and authentication will be provided accordingly. 5. Wrote actions for this complex syntax(fixed some of the errors, some are yet to be fixed). In the remaining 3-4 days of Phase-1, I will try to complete this bridge between grammar and in-memory structure after which storing data in memory will be done. Now coming on to phase-2 deliverables, I am planning to finish off with Storage on Disk. We have found a simplest solution to get this done(probably in a week or 2), and in the remaining days, we will check the working of this new feature. I will then migrate this code to 10.3 branch. (Phase-3 for unexpected delay) This project involve lots of thinking than actual coding, so I think I have maintained good pace throughout. I believe I will maintain this enthusiasm and confidence level in upcoming phases too. Hopefully, I will get a chance to continue with this project. Kind regards, Ankit Kumar

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