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Has anyone implemented InnoDB redo log-based physical replication?
by Otto Kekäläinen 04 Mar '25

04 Mar '25

Hi, Has anyone attempted or seen any existing implementations "physical" replication between two MariaDB instances, where a secondary read-only instance would follow the primary by directly reading and applying page changes from the primary's redo logs? The secondary instance would start (and restart if necessary) using a full copy of the data from the primary instance, but while running keep itself current by reading redo logs from the primary instance, and apply pages based on the increasing LSN number. I call this "physical" replication to distinguish it from normal logical replication based on e.g. binlogs, and this would obviously only work for InnoDB. Thanks, Otto

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Review request for MariaDB 2025 Q1 uploads to Debian and Ubuntu
by Otto Kekäläinen 24 Feb '25

24 Feb '25

Hi! Thanks Vicentiu for reviewing https://salsa.debian.org/mariadb-team/mariadb-server/-/merge_requests/102 The next uploads in line are ready for review at: https://salsa.debian.org/mariadb-team/mariadb-server/-/merge_requests/98 Prepare MariaDB Server 1:10.11.11-0+deb12u1 minor maintenance release for Debian stable (Bookworm) https://salsa.debian.org/mariadb-team/mariadb-server/-/merge_requests/106 Prepare upload to MariaDB 10.11.9 to Ubuntu 24.04 "Noble" https://salsa.debian.org/mariadb-team/mariadb-server/-/merge_requests/96 Prepare upload to MariaDB 10.6.19 to Ubuntu 22.04 "Jammy" https://salsa.debian.org/mariadb-team/mariadb-10.5/-/merge_requests/20 New upstream version MariaDB 10.5.28 for Debian 11 "Bullseye" Once I am done with these, I will start testing MariaDB 11.8 with the goal of uploading it into Debian in the coming weeks.

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Re: [PATCH] MDEV-36099 Ensure that creation and usage of temporary tables in replication is predictable
by Kristian Nielsen 23 Feb '25

23 Feb '25

Hi Monty, > From: Monty <monty(a)mariadb.org> > > The purpose of this commit is to ensure that creation and changes of > temporary tables are properly and predicable logged to the binary > log. It also fixes some bugs where ROW logging was used in MIXED mode, > when STATEMENT would be a better (and expected) choice. Here is my review of the patch for MDEV-36099 predictable binlog format for temporary tables: Overall this seems like solid work, thanks! As Elena also remarked, this does significant changes to a very tricky and bug-ridden area of replication, that of temporary tables, this is scary stuff. But the patch does look good and relatively simple. A main change with this patch is that now all use of temporary tables will by default be binlogged in row mode. I think this is a reasonable change. There are still remaining problems with temporary tables in statement-based mode; and it also helps with parallel replication, which cannot run in parallel statement-logged temporary tables. And you provided --create-temporary-table-binlog-formats as a way to enable backwards-compatible behaviour. I think it is important to mention this prominently in the release notes. There will invariably be some users that manipulate a large number of rows with temporary tables, eg. BEGIN; CREATE TEMPORARY TABLE tmp AS SELECT a, b, c FROM large_table1 JOIN large_table2 ON ... INSERT INTO other_table SELECT b, c FROM tmp WHERE a <100; DROP TEMPORARY TABLE tmp; COMMIT; This will change from binlogging a few hundred bytes of Query events to potentially many megabytes of row events, which could cause problems in some cases. I think the change is still justified from the benefits it gives and the relative few cases where this will cause serious problems, but it is still important to try to document it as well as possible. I read the code part of the patch through in detail, but I did not spot anything in it that looks wrong. There may be things missing from the patch that are hard to spot in a review, I think that's unavoidable in a change like this. But I did try to think of possible issues without finding anything, and the patch does look quite simple compared to what it is doing. So looks good I think. Just a few questions on details I did not understand, and some minor suggestions for changes. Questions: > diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc > index c2f842aea56..3d1df5ac42f 100644 > --- a/sql/sql_parse.cc > +++ b/sql/sql_parse.cc > @@ -531,6 +531,7 @@ void init_update_queries(void) > CF_SCHEMA_CHANGE; > sql_command_flags[SQLCOM_CREATE_SEQUENCE]= (CF_CHANGES_DATA | > CF_REEXECUTION_FRAGILE | > + CF_FORCE_ORIGINAL_BINLOG_FORMAT | > CF_AUTO_COMMIT_TRANS | > CF_SCHEMA_CHANGE); I did not get the reason for this change. I assume some bug fix found during test case writing? > --- a/sql/sql_class.h > +++ b/sql/sql_class.h > @@ -817,6 +817,7 @@ typedef struct system_variables > /* Flags for slow log filtering */ > ulong log_slow_rate_limit; > ulong binlog_format; ///< binlog format for this thd (see enum_binlog_format) > + ulong create_temporary_table_binlog_formats; Is there any way to make this take less space than 8 bytes (on 64-bit)? It goes into every THD, and only two bits are used. > + > + Temporary tables will be logged only on CREATE in STMT format > + or on INSERT if all changes to the table is in the binlog. > */ > if ((WSREP_EMULATE_BINLOG(thd) || mysql_bin_log.is_open()) && > - (likely(!error) || thd->transaction->stmt.modified_non_trans_table || > - thd->log_current_statement())) > + (table->s->using_binlog() || > + ((in_create_table && > + (!table->s->tmp_table || thd->binlog_create_tmp_table())))) && > + (likely(!error) || > + (!in_create_table && > + (thd->transaction->stmt.modified_non_trans_table || > + thd->log_current_statement())))) This conditional is now very hard to understand. I think I managed to understand all parts of it, except the part "thd->log_current_statement()", but that is unchanged with your patch. This if () would now benefit from being split into multiple parts, each of which explained in a comment. > diff --git a/mysql-test/main/statistics.result b/mysql-test/main/statistics.result > index bb6469c46da..ebd9cb7f36e 100644 > --- a/mysql-test/main/statistics.result > +++ b/mysql-test/main/statistics.result > @@ -1278,7 +1278,7 @@ Table Op Msg_type Msg_text > mysql.column_stats analyze error Invalid argument > ANALYZE TABLE mysql.column_stats; > Table Op Msg_type Msg_text > -mysql.column_stats analyze status OK > +mysql.column_stats analyze status Table is already up to date > SELECT * FROM mysql.table_stats; > db_name table_name cardinality > SELECT * FROM mysql.column_stats; I did not understand why this .result change happens after your patch? Minor things: > diff --git a/mysql-test/suite/rpl/t/create_or_replace.inc b/mysql-test/suite/rpl/t/create_or_replace.inc > index e8fa95cb94a..b4e91d7b412 100644 > --- a/mysql-test/suite/rpl/t/create_or_replace.inc > +++ b/mysql-test/suite/rpl/t/create_or_replace.inc > @@ -4,7 +4,24 @@ > --let $rpl_topology=1->2 > --source include/rpl_init.inc > > -# Create help tables > +select @@binlog_format, @@create_temporary_table_binlog_formats; > + > +# Copy create_temporary_table_binlog_formats from master to slave > +# This is done to get same results as with older versions of MariaDB. > +# The slave will work even if this is not done. However in mixed > +# format on slave temporary tables would not be logged to in the > +# slaves binary log > +let $format=`select @@create_temporary_table_binlog_formats`; > +connection server_2; > +--eval set @@global.create_temporary_table_binlog_formats='$format' > +# Ensure that the slave threads uses the new values. > +stop slave; > +start slave; Here, use --source include/stop_slave.inc and --source include/start_slave.inc. For consistent with other test cases. > - Rename of not binlogged temporary tables where binlogged to binary log > which caused replication to stop. s/where/were/ > + /* > + Mark if query was logged as statement. Used to check it tmp table changes > + are logged. > + */ > + bool query_binlogged_as_stmt; s/check it table/check if table/ + /* + This is set for all normal tables and for temporary tables that has + the CREATE binary logged. + + 0 table table is not in binary log (not logged temporary table) + 1 table create was logged (normal table or logged temp table) + 2 table create was logged but not all changes are in the binary log. + ROW LOGGING will be used for the table. s/that has the CREATE/that have the CREATE/ s/table table is not/table is not/ > @@ -794,6 +821,20 @@ void THD::mark_tmp_table_as_free_for_reuse(TABLE *table) > > DBUG_ASSERT(table->s->tmp_table); > > + /* > + Ensure that table changes where either binary logged or the table > + is marked as not up to date. > + */ s/where/were/ Thanks, Monty! Reviewed-by: Kristian Nielsen <knielsen(a)knielsen-hq.org> - Kristian.

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MDEV-33671: MTR Safe Process Hardcodes RLIMIT_NOFILE
by mohanadkhaled87＠gmail.com 11 Feb '25

11 Feb '25

Hello I am Mohanad and this is my first issue here I started working on this issue a while ago but only began testing it recently. As per the comment in this issue (https://jira.mariadb.org/browse/MDEV-33671?focusedCommentId=281856&page=com…) "You can run ulimit from Perl, between the fork and exec." I implemented this by using the BSD::Resource library, as it appears to be part of the core Perl libraries and does not introduce an external dependency and as a sanity check I added ```perl my $has_bsd_resource = eval { require BSD::Resource; BSD::Resource->import(qw(setrlimit getrlimit RLIMIT_NOFILE)); 1; }; ``` Would this be an okay to use ? Also, I have manually verified the implementation by printing the limit values. However, is it possible to add test files or automate testing for this issue in MTR ?

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Current status on MDEV-34705 binlog-in-engine
by Kristian Nielsen 09 Feb '25

09 Feb '25

Hi Brandon (and other interested), It is great that you want to look closer at the MDEV-34705, binlog-in-engine project. I wanted to write up a high-level summary of the current status to help you get an overview. For reference, this is a project to implement a new binlog format that solves some of the complexity and performance problems with the old format that is not integrated with the storage engine transaction log (eg. InnoDB binlog). The code is being developed on the branch knielsen_binlog_in_engine on Github, https://github.com/MariaDB/server/commits/knielsen_binlog_in_engine There has been some previous design discussions on the mailing list, eg.: https://lists.mariadb.org/hyperkitty/list/developers@lists.mariadb.org/thre… https://lists.mariadb.org/hyperkitty/list/developers@lists.mariadb.org/thre… - Kristian. Current status: - Feature is off by default, enabled by --binlog-storage-engine=innodb. - Binlog files are now identified solely with their file_no, starting from 0 (no more master-bin.index). Binlog file names are hard-coded by the engine (binlog-NNNNNN.ibb), directory can be selected with --binlog-directory. - Binlog files are pre-allocated to --max-binlog-size, thus their size is fixed. Event groups and even events can span multiple binlog files. - New binlog format is page-based. On server start, binary search is used to find the current position (no need for scanning a whole binlog file). GTID start position is likewise found by binary search, no need for separate GTID index. - Binlog files are written strictly append-only, data is never updated after initial write. The InnoDB redo log is used to ensure that files are recovered into a consistent state with the engine data after a crash. - Large event groups (larger than --binlog-cache-size) are split into pieces that are binlogged "out-of-band", meaning they are written in separate records during transaction execution, before commit. The final commit record merely has a reference to the out-of-band data. Out-of-band data for rolled-back transactions remain as "garbage" until binlog purge. - The binlog dump thread re-assembles out-of-band data into consecutive event groups for the slaves. Thus, slaves see event data in the same format as before, no slave code changes needed. Out-of-band data is structured as complete binary trees for efficient reading. - Basic slave replication is working, not much is tested though. Currently GTID mode only, might make sense to not support filename/position mode for simplicity. - RESET MASTER, FLUSH BINARY LOGS, PURGE BINARY LOGS are implemented. - Initial benchmarking show good speedup (x2) in durable configuration, potentially huge (3 to sevelal hundred times faster) speedup in crash-safe configuration. A main challenge with this project is that the binlog internals are visible in so many places to users, and to other parts of the code. Here is an (incomplete) list of major issues still to implement: - The current implementation is using the normal InnoDB buffer pool and checkpoint mechanism. See the mailing list discussions for Marko's ideas for implementing a simpler integration with the InnoDB redo log. - When --sync-binlog=1, implement that binlog events are not sent to slaves until durably written to redo log. When --sync-binlog=0, implement that events are not sent until redo log is (non-durably) written (--innodb-flush-log-at-trx-commit=2). - mysqlbinlog ability to read new binlog format. The code is there, mostly a matter of finding a good way to share code between the server/InnoDB and mysqlbinlog.cc. - Disable all parts of the legacy binlog when --binlog-storage-engine is set (in current code some parts still remain active). - SHOW BINLOG EVENTS. - Binlog checksum and encryption. Will checksum and encrypt the individual pages, not use the legacy per-event checksums or encryption. - Storage engine API. The functionality is implemented, but the design of the API and interfaces might need review and cleanup, ie. maybe parts to be implemented as services (include/service_versions.h etc.) - Lots of smaller ToDo:s, some marked in comments in the code. - There is a --suite=binlog_in_engine, but a lot more testing is neeed. Some parts may be initially not supported in the first release, but implemented later: - Semi-synchronous replication. Should be straight-forward to implement later. Might make sense to use GTID to send back-and-forth instead of filename/offset. AFTER_SYNC no longer makes sense, but could consider implementing AFTER_PREPARE. - External XA, to be implemented following MDEV-32020. The out-of-band mechanism will be used so that XA COMMIT can reference the binlog data and replicate without the need for any transactions to be in XA PREPARED state on the slave or in backups.

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Next step on MDEV-34705, implement binlog in InnoDB
by Kristian Nielsen 30 Jan '25

30 Jan '25

Hi Marko, Time flies, somehow it's already more than a year since our first discussions on implementing the binlog in InnoDB and avoiding the extra fsync() and complexity of the two-phase commit between InnoDB and binlog. But things have progressed, and I have now reached the point where most of the basic groundwork is implemented. Event groups are binlogged to InnoDB tablespaces. Binlog dump thread can read the binlog and send to slave, and replication is working. Large event groups are split into pieces, bounding the amount of data that needs to be atomically written in mini-transactions and at commit time. There are still many details left, but mostly in the server-layer replication code which should be manageable, just will take some time to get completed. I think now is a good time for you to take a first real look at the InnoDB part of the changes, I would really value your input. The main part of the InnoDB code is in two files: 1. handler/handler0binlog.cc for the high-level part that deals mostly with the new binlog file format and interfacing to the server layer. 2. fsp/fsp0binlog.cc for the low-level part that most tightly interacts with the InnoDB mini-transactions and buffer pool. The most interesting part for you to look at is fsp/fsp0binlog.cc (~1k lines), though I'm happy to hear comments on any part of the patch, of course. The code is pushed to GitHub in the branch knielsen_binlog_in_engine: https://github.com/MariaDB/server/commits/knielsen_binlog_in_engine and I've also attached the complete patch. This is my first major patch for InnoDB, so there will undoubtedly be a number of style changes required. But the overall structure of the code should now be close to what I imagine would be the final result, with some pending ToDo steps marked in comments in the code, and detailed in the below list, some of which we discussed a bit already. I hope you will take a look at the patch and let me know of any questions or other things you need from me. Maybe we can also find a chance to discuss further if you will come to FOSDEM start of February, or I could visit sometimes in Finland. - Kristian. ---- Some known outstanding issues in the InnoDB part: - We previously discussed removing some of the page header overhead for binlog tablespaces. Currently the code just leaves alone the first FIL_PAGE_DATA bytes (38) and the last FIL_PAGE_DATA_END (8 IIRC). - We discussed previously to write the current LSN at the start of the tablespace, and use this in recovery to handle that we have only two tablespace IDs that are reused. So we need code in recovery that checks the LSN at the start of the tablespace, and skips redo records with LSN smaller than this. - We want to avoid the double-write buffer for binlog pages, at least for the first page write (most pages will only be written as full pages). You mentioned an idea to completely avoid the double-write buffer and instead do some specific code for recovery in the uncommon case where a partial binlog page is written to disk due to low commit activity. - The flushing of binlog pages to disk currently happens in a dedicated thread in the background. I'd welcome ideas on how to do this differently. It is good to flush binlog pages quickly and re-use their buffer pool entries for something better. Also writing the pages to disk quickly (not necessarily fsync()'ing) makes the data readable by mysqlbinlog. - Checksum and encryption should use the standard InnoDB mechanism. I assume checksum is already handled in the code through using the buffer pool and mini-transactions to read/write pages. Not sure about encryption. I need to implement that the code handles checksum and decryption when reading the pages manually from the file (not through buffer pool).

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2025 Q1 release - near final
by Daniel Black 29 Jan '25

29 Jan '25

The issue where this is tracked is: https://jira.mariadb.org/browse/MDEV-35789 Current blockers: https://jira.mariadb.org/issues/?filter=31019&jql=project%20in%20(mdev)%20A… The "fix version" in the above url list all are 11.4+ so all LTS versions should be stable. Branches bb-10.5-release (LTS) bb-10.6-release (LTS) bb-10.11-release (LTS) bb-11.4-release (LTS) bb-11.7-release (stable for first time) bb-11.8-release (gamma - no LTS announcement made) If there's regression particularly impacting please ensure the issue has a blocker priority, with a good business case reason why it should block, and make as blocks MDEV-35789. In addition to compiling the source yourselves: Containers: quay.ion/mariadb-foundation/mariadb-devel:{release} list: https://quay.io/repository/mariadb-foundation/mariadb-devel?tab=tags note: * pushes to *-release branch also gains the same tag as the main 10.X, 11.X tags. Check commit at the beginning of the server startup to determine actual commit. Repos for testing (packages may not last more than a few weeks at urls): https://ci.mariadb.org/ contains for deb and rpm distros a repo file in the form: bb-{version}-release-latest-{arch}-{distro}-{version}-{deb|rpm}-autobake.{sources|repo}

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Parameterized queries
by E.S. Rosenberg 27 Jan '25

27 Jan '25

Hi, Recently I found out about parameterized queries in MySQL, it seems to have been supported at least since 8.0.x but it is not listed as an incompatibility between mariadb and mysql yet the package spec for COM_QUERY on mariadb does not mention any support for parameterized queries. So is this an incompatibility, some out of date docs or am I just looking at the wrong com_query page? Refs: https://dev.mysql.com/doc/dev/mysql-server/8.0.40/page_protocol_com_query.h… https://mariadb.com/kb/en/com_query/ Thanks! Eli

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Re: 6a4b85ce1cc: MDEV-20281 "[ERROR] Failed to write to mysql.slow_log:" without error reason
by Sergei Golubchik 25 Jan '25

25 Jan '25

Hi, Oleksandr, Ok to push after fixing spagetty (either by fixing a typo or by changing the code pattern as suggested below). On Jan 25, Oleksandr Byelkin wrote: > revision-id: 6a4b85ce1cc (mariadb-10.5.27-202-g6a4b85ce1cc) > parent(s): d261fa5c703 > author: Oleksandr Byelkin > committer: Oleksandr Byelkin > timestamp: 2025-01-24 17:24:17 +0100 > message: > > MDEV-20281 "[ERROR] Failed to write to mysql.slow_log:" without error reason > > Add "backup" (in case of absence issued by error) reasons for failed logging. > > @@ -998,6 +1047,9 @@ bool Log_to_csv_event_handler:: > close_log_table(thd, &open_tables_backup); > thd->time_zone_used= save_time_zone_used; > DBUG_RETURN(result); > +store_err: // spagetty, but reduce size of the code > + cause= "Can't write data (possible incorrect log table structure)"; > + goto err; > } typo. it's "spaghetti" but may be better to avoid it altogether by rewriting as cause= "..."; if (field[0]->store(...)) goto err; if (field[1]->store(...)) goto err; if (field[2]->store(...)) goto err; ... cause= NULL; Regards, Sergei Chief Architect, MariaDB Server and security(a)mariadb.org

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Re: 0b403e03939: MDEV-35661 Assertion `!cache_list ||...' fails in online_alter_close_connection
by Sergei Golubchik 22 Jan '25

22 Jan '25

Hi, Nikita, On Jan 19, Nikita Malyavin wrote: > revision-id: 0b403e03939 (mariadb-11.7.1-16-g0b403e03939) > parent(s): 40e502eca4c > author: Nikita Malyavin > committer: Nikita Malyavin > timestamp: 2025-01-03 00:54:52 +0100 > message: > > MDEV-35661 Assertion `!cache_list ||...' fails in > online_alter_close_connection > > After MDEV-35182 (88adcbf3) fix, online_alter still wasn't fully ready > for `XA PREPARE` to be skipped. > > In fact, according to XA standard, even xa_commit() call may happen > without preceding xa_prepare(), so this stage is completely optional. > > This commit removes any relying on xa_prepare() call. The only thing > that will be done there is an equivalent of "statement-level commit", > which basically just flushes a pending rows event to an online alter > cache. > > This is done by always storing an online alter cache in the XA_data > object whenever XA is active, rather than in THD::ha_data. Why? I thought it'd be simpler to keep the cache in the THD and take it off it in commit or rollback. That is, almost as now, but commit/rollback won't rely on prepare being called before. Regards, Sergei Chief Architect, MariaDB Server and security(a)mariadb.org

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