Fun with Bugs #90 - On MySQL Bug Reports I am Subscribed to, Part XXIV

Previous post in this series was published 3 months ago and the last Bug #96340 from it is already closed as fixed in upcoming MySQL 8.0.19. I've picked up 50+ more bugs to follow since that time, so I think I should send quick status update about interesting public MySQL bug reports that are still active.

As usual I concentrate mostly on InnoDB, replication and optimizer bugs. Here is the list, starting from the oldest:

• Bug #96374  - "binlog rotation deadlock when innodb concurrency limit setted". This bug was reported by Jia Liu, who used gdb to show threads deadlock details. I admit that recently more bug reporters use gdb and sysbench with custom(ized) Lua scripts to prove the point, and I am happy to see this happening!
• Bug #96378 - "Subquery with parameter is exponentially slower than hard-coded value". In my primitive test with user variables replaced by constants (on MariaDB 10.3.7) I get the same plan for the query, so I am not 100% sure that the analysis by my dear friend Sinisa Milivojevic was right and it's about optimization (and not comparing values with different collations, for example). But anyway, this problem reported by Jeff Johnson ended up as a verified feature request. Let's see what may happen to it next.
• Bug #96379 - "First query successful, second - ERROR 1270 (HY000): Illegal mix of collations ". This really funny bug was reported by Владислав Сокол.
• Bug #96400 - "MTS STOP SLAVE takes over a minute when master crashed during event logging". Nice bug report by Przemyslaw Malkowski from Percona, who used sysbench and dbdeployer to demonstrate the problem. Later Przemysław Skibiński (also from Percona) provided a patch to resolve the problem.
• Bug #96412 - "Mess usages of latch meta data for InnoDB latches (mutex and rw_lock)". Fungo Wang had to make a detailed code analysis to get this bug verified. I am not sure why it ended up with severity S6 (Debug Builds) though.
• Bug #96414 - "CREATE TABLE events in wrong order in a binary log.". This bug was reported by Iwo P. His test case to demonstarte the problem included small source code modification, but (unlike with some other bug reports) this had NOT prevented accepting it as a true, verified bug. The bug not affect MySQL 8.0.3+ thanks to WL#6049 "Meta-data locking for FOREIGN KEY tables" implemented there.
• Bug #96472 - "Memory leak after 'innodb.alter_crash'". Yet another bug affecting only MySQL 4.7 and not MySQL 8.0. It was reported by Yura Sorokin from Percona.
• Bug #96475 - "ALTER TABLE t IMPORT TABLESPACE blocks SELECT on I_S.tables.".  Clear and simple "How to repeat" instructions (using dbdeployer) by Jean-François Gagné. See also his related Bug #96477 - "FLUSH TABLE t FOR EXPORT or ALTER TABLE t2 IMPORT TABLESPACE broken in 8.0.17" for MySQL 8. The latter is a regression bug (without a regression tag), and I just do not get how the GA releases with such new bugs introduced may happen.
• Bug #96504 - "Refine atomics and barriers for weak memory order platform". Detailed analysis, with links to code etc from Cai Yibo.
• Bug #96525 - "Huge malloc when open file limit is high". Looks more like a systemd problem (in versions < 240) to me. Anyway, useful report from Andreas Hasenack.
• Bug #96615 - "mysql server cannot handle write operations after set system time to the past". A lot of arguments were needed to get this verified, but Shangshang Yu was not going to give up. First time I see gstack used in the bug report to get a stack trace quickly. It's a part of gdb RPM on CentOS 6+. I have to try it vs gdb and pstack one day and decide what is the easiest and most efficient way to get backtraces of all threads in production...
• Bug #96637 - "Clone fails on just upgraded server from 5.7". I had not used MySQL 8 famous clone plugin yet in practice, but I already know that it has bugs. This bug was reported by Satya Bodapati, who also suggested a patch.
• Bug #96644 - "Set read_only on a master waiting for semi-sync ACK blocked on global read lock". Yet another problem (documented limitation) report from Przemyslaw Malkowski. Not sure why it was not verified on MySQL 8.0. Without a workaround to set master to read only it is unsafe to use long rpl_semi_sync_master_timeout values, as we may end up with that long downtime.
• Bug #96677 - ""SELECT ... INTO var_name FOR UPDATE" not working in MySQL 8". This regression bug was reported by Vinodh Krish. Some analysis and patch were later suggested by Zsolt Parragi.
• Bug #96690 - "sql_require_primary_key should not apply to temporary tables". This bug was also reported by Przemyslaw Malkowski from Percona. It ended up as a verified feature request, but not everyone in community is happy with this. Let me quote:
  

  "[30 Aug 8:08] Jean-François Gagné
  Could we know what was the original severity of this bug as reported by Przemyslaw ? This is now hidden as it has been reclassified as S4 (Feature Request).
  
  From my point of view, this is actually a bug, not a feature request and it should be classified as S2. A perfectly working application would break for no reason when a temporary table does not have a Primary Key, so this is actually a big hurdle for using sql_require_primary_key, hence serious bug in the implementation of this otherwise very nice and useful feature."

That's all about bugs I've subscribed to in summer.

Winter is coming, so why not to remember nice warm sunny days and interesting MySQL bugs reported back then.

To summarize:

1. We still see some strange "games" played during bugs processing and trend to decrease severity of reports. I think this is a waste of time for both Oracle engineers and community bug reporters.
2. I am still not sure if Oracle's QA does not use ASan or just ignore problems reported for MTR test cases. Anyway, Percona engineers do this for them, and report related bugs :)
3. dbdeployer and sysbench are really popular among MySQL bug reporters recently!
4. Importing of InnoDB tablespaces is broken in MySQL 8.0.17+ at least.
5. There are many interesting MySQL bugs reported during last 3 months, so I epxect more posts in this series soon.

Fun with Bugs #89 - On MySQL Bug Reports I am Subscribed to, Part XXIII

I have to celebrate the anniversary of my last day in Oracle (that was 7 years ago!) somehow, and I think writing yet another blog post about Oracle MySQL bugs is a good way to do this. I am actually surprised (and happy) that public bugs database is still alive, maintained and considered important in Oracle, and I know who in Oracle was working hard all these years for this to happen!

In my previous post in this series I've stopped on Bug #95954 and had not completed review of interesting MySQL bug reports that I've subscribed to in June 2019. So, below I start with the next bug in my list, complete review for June and cover some bugs reported in July. There were many.

• Bug #95957 - "IN operator issue when comparing signed column and the column cast to unsigned". This bug was reported by Manuel Rigger. As far as I can see, MariaDB 10.3 is not affected:
  

  MariaDB [test]> CREATE TABLE t0(c0 INT);
  Query OK, 0 rows affected (0.518 sec)
  
  MariaDB [test]> INSERT INTO t0(c0) VALUES(-1);
  Query OK, 1 row affected (0.196 sec)
  
  MariaDB [test]> SELECT t0.c0 IN (1, CAST(t0.c0 AS UNSIGNED)) from t0;
  +---------------------------------------+
  | t0.c0 IN (1, CAST(t0.c0 AS UNSIGNED)) |
  +---------------------------------------+
  |                                     0 |
  +---------------------------------------+
  1 row in set, 1 warning (0.207 sec)
  
  MariaDB [test]> show warnings\G
  *************************** 1. row ***************************
    Level: Note
     Code: 1105
  Message: Cast to unsigned converted negative integer to it's positive complement
  
  1 row in set (0.013 sec)

• Bug #96001 - "No warning when creating foreign key in MyISAM tables". I am really surprised that this "documented feature" was accepted as a S3 bug when reported by Przemyslaw Malkowski from Percona. But this happened. I also prefer NOT to have unsupported syntax just ignored silently and would like to see a warning (or error in strict mode).
• Bug #96002 - "'variable log_bin_trust_function_creators' -variable is "hidden"." Consistency is important, as well as correct documentation. So I was happy to see this bug report from Peter Laursen. 75(!) of his bug reports are still active, by the way, some were reported more than 10 years ago. I wonder if anyone is going to check (if not fix) them any time soon.
• Bug #96079 - "large_tests.innodb_innochecksum_3gb test failing with debug build." Yet another MTR test failure reported by Lalit Choudhary from Percona.
• Bug #96100 - "Generated column cause a heap-use-after-free error". Probably ASan builds are not tested as carefully in Oracle as they are by some community members, like Zkong Kong who reported this bug. Otherwise they would mark this bug report as a duplicate of some known internal bug.
• Bug #96108 - "To run mtr "innodb.log_flush_order" MySql Server would be always core down". I've listed the bug as an example that even though code modification is needed to reproduce the crash (reported by Juncai Meng) literally, it was accepted and "Verified". In other reports this sometimes not happen, and the point is that it is surely not a rule carved in stone in Oracle to NOT accept bugs if test case involves code modification. Remember that and fight for your reports if needed.
• Bug #96128 - "Doc: documentation is inaccurate when InnoDB starts with innodb_read_only". Correct manual matters a lot, so nice to have it corrected in this case by Calvin Sun.
• Bug #96134 - "Please provide control functions for the IO Thread." I'd be also happy to see a way to control replication I/O thread progress and read logs only up to some position or GTID, per channel. Thanks Jean-François Gagné for this nice feature request.
• Bug #96142 - "Inconsistent error on slave for Update event on table with non-exists partition". Yet another by report from by Lalit Choudhary. Good to see multiple versions check.
• Bug #96148 - "using Invisible Index when slave apply EVENT". This bug was reported by Songlei Wang. Consistency matters, so if the index is invisible it should remain invisible for replication SQL thread as well. See also his another Bug #96150 - "'show slave status' show the Inaccurate Last_IO_Error message".
• Bug #96167 - "Many header files now missing from devel package". As noted by Manuel Ung, now it is impossible to build plugins and UDFs unless users download the source tree, and then copy the headers to the appropriate places. Packaging in hard.
• Bug #96178 - "mysqldump leaks memory when selected tables are dumped with --order-by-primary". Abhinav Sharma proposed a simple MTR test case to run on ASan build, and suggested a fix. Very nice bug report. Unfortunately I do not see any statements about the results of checking MySQL 8.0.x.
• Bug #96192 - "Possible race condition with binlog-transaction-dependency-tracking". Bug reporter, Herman Lee, complained about one place in the code where race condition may happen even after the fix for one MySQL bug. Does it really matter for bug verification if he found more places? I fail to see a reason to keep he bug in "Need Feedback" status, when code review is enough to confirm there is a problem in that one part of the code clearly identified.
• Bug #96196 - "performance_schema_accounts_size and p_s_hosts_size limited by 16384", Nice bug that can be confirmed by code review or just opening many connections was reported by Nikolai Ikhalainen from Percona. Autoscaling is broken/limited in this case.
• Bug #96340 - "Slow startup for mysql 8.0 with many tables due to the tablespace files scan". This is actually a regression comparing to 5.7, but it's visible on slow disks. It's nice to see useful discussion, explanations and patch suggested (by Sunny Bains) in this bug report created by Lalit Choudhary.

I started this summer in a beautiful Barcelona. This blog posts ends it for me. One of the good changes leaving Oracle seven years ago introduced in my life is a real freedom to work from anywhere and travel as often as I really want, both for work and for fun.

To summarize:

1. I am happy to see MySQL public bugs database still up and widely used, even though I do not work on it directly for 7 years already. It's a key service and media for cooperation for the entire MySQL Community! Just check how it happens in Bug #96340.
2. Consistency matters.
3. I still see cases when the time is wasted at bugs verification stage.
4. MySQL fine manual still have details explained incorrectly, and this is unfortunate.
5. Sometime I wonder why Percona engineers and other MySQL Community users manage to find even MTR test failures faster than anyone in Oracle cares to report and fix them. They all know magic (like actually running all tests on debug builds and checking the results, maybe). Or, maybe, they care?

* * *

Shameless self-promotion at the end. First time since 2015 I am going to attend Percona Live conference and speak there. Ticket prices increase on September 1, so using code CMESPEAK-VALERII you’ll get the best deal right now.

Fun with Bugs #85 - On MySQL Bug Reports I am Subscribed to, Part XX

We have a public holiday here today and it's raining outside for a third day in a row already, so I hardly have anything better to do than writing yet another review of public MySQL bug reports that I've subscribed to recently.

Not sure if these reviews are really considered useful by anyone but few of my readers, but I am still going to try in a hope to end up with some useful conclusions. Last time I've stopped on Bug #94903, so let me continue with the next bug in my list:

• Bug #94912 - "O_DIRECT_NO_FSYNC possible write hole". In this bug report Janet Campbell shared some concerns related to the way O_DIRECT_NO_FSYNC (and O_DIRECT) settings for innodb_flush_method work. Check comments, including those by Sunny Bains, where he agrees that "...this will cause problems where the redo and data are on separate devices.". Useful reading for anyone interested in InnoDB internals or using  innodb_dedicated_server setting in MySQL 8.0.14+.
• Bug #94971 - "Incorrect key file error during log apply table stage in online DDL". Monty Solomon reported yet another case when "online' ALTER for InnoDB table fails in a weird way. The bug is still "Open" and there is no clear test case to just copy/paste, but both the problem and potential solutions (make sure you have "big enough" innodb_online_alter_log_max_size or better use pt-online-schema-change or gh-ost tools) were already discussed here.
• Bug #94973 - "Wrong result with subquery in where clause and order by". Yet another wrong results bug with subquery on MySQL 5.7.25 was reported by Andreas Kohlbecker. We can only guess if MySQL 8 is also affected (MariaDB 10.3.7 is not, based on my test results shared below) as Oracle engineer who verified the bug had NOT card to check or share the results of this check. What can be easier than running this (a bit modified) test case on every MySQL major version and copy pasting the results:
  

  MariaDB [test]> CREATE TABLE `ReferenceB` (
      ->   `id` int(11) NOT NULL,
      ->   `bitField` bit(1) NOT NULL,
      ->   `refType` varchar(255) NOT NULL,
      ->   `externalLink` longtext,
      ->   PRIMARY KEY (`id`)
      -> ) ENGINE=MyISAM DEFAULT CHARSET=utf8;
  Query OK, 0 rows affected (0.170 sec)
  
  MariaDB [test]> INSERT INTO ReferenceB (id, bitField, refType, externalLink) VALUES(1, 0, 'JOU', NULL);
  Query OK, 1 row affected (0.027 sec)
  
  MariaDB [test]> INSERT INTO ReferenceB (id, bitField, refType, externalLink) VALUES(2, 0, 'JOU', NULL);
  Query OK, 1 row affected (0.002 sec)
  
  MariaDB [test]> SELECT hex(bitField) from ReferenceB  where id in (select id as
  y0_ from ReferenceB  where refType='JOU') order by externalLink asc;
  +---------------+
  | hex(bitField) |
  +---------------+
  | 0             |
  | 0             |
  +---------------+
  2 rows in set (0.028 sec)

  But we do not see anything like that in the bug report... This is sad.
• Bug #94994 - "Memory leak detect on temptable storage engine". Yet another memory leak (found with ASan) reported by Zhao Jianwei, who had also suggested a patch.
• Bug #95008 - "applying binary log doesn't work with blackhole engine tables". This bug was reported by Thomas Benkert. It seems there is a problem to apply row-based events to BLACKHOLE table and this prevents some nice recovery tricks from working.
• Bug #95020 - "select no rows return but check profile process Creating sort index". Interesting finding from cui jacky. I can reproduce this with MariaDB as well. It seems we either have to define some new stage or define "Creating sort index" better than in the current manual. This:
  

  The thread is processing a SELECT that is resolved using an internal temporary table.

  is plain wrong in the case shown in the bug report IMHO.
• Bug #95040 - "Duplicately remove locks from lock_sys->prdt_page_hash in btr_compress". One of those rare cases when Zhai Weixiang does not provide the patch, just suggests the fix based on code review :)
• Bug #95045 - "Data Truncation error occurred on a write of column 0Data was 0 bytes long and". This really weird regression bug in MySQL 8.0.14+ was reported by Adarshdeep Cheema. MariaDB 10.3 is surely not affected.
• Bug #95049 - "Modified rows are not locked after rolling back to savepoint". Bug reporter, John Lin, found that fine MySQL manual does not describe the real current implementation. Surprise!
• Bug #95058 - "Index not used for column with IS TRUE or IS FALSE operators". Take extra care when using BOOLEAN columns in MySQL. As it was noted by Monty Solomon, proper index is NOT used when you try to check BOOLEAN values as manual suggests, using IS TRUE or IS FALSE conditions. Roy Lyseng explained how such queries are threated internally, but surely there is a better way. MariaDB 10.3.7 is also affected, unfortunately.
• Bug #95064 - "slave server may has gaps in Executed_Gtid_Set when a special case happen ". Nice bug report from yoga yoga, who had also contributed a patch. Parallel slave can easily get out of sync with master in case of lock wait timeout and failed retries. Again, we do NOT see any check if MySQL 8 is affected, unfortunately.
• Bug #95065 - "Strange memory management when using full-text indexes". We all know that InnoDB FULLTEXT indexes implementation is far from perfect. Now, thanks to Yura Sorokin, we know also about a verified memory leak bug there that may lead to OOM killing of MySQL server.
• Bug #95070 - "INSERT .. VALUES ( .., (SELECT ..), ..) takes shared lock with READ-COMMITTED". Seunguck Lee found yet another case of InnoDB locking behavior that MySQL manual does not explain. The bug is still "Open" for some reason.
• Bug #95115 - "mysqld deadlock of all client threads originating from 3-way deadlock". It took some efforts for bug reporter, Sandeep Dube, and other community users (mostly Jacek Cencek) to attract proper attention to this bug from proper Oracle developer, Dmitry Lenev, until it ended up "Verified" based on code review. We still can not be sure if MySQL 8 is also affected.

That's all for now. I have few more new bug reports that I monitor, but I do not plan to continue with this kind of reviews in upcoming few months in this blog. I hope I'll get a reason soon to write different kind of posts, with more in depth study of various topics...

In any case you may follow me on Twitter for anything related to recent interesting or wrongly handled MySQL bug reports.

This view of Chelsea from our apartment at Chelsea Cloisters reminds me that last year I spent spring holiday season properly - no time was devoted to MySQL bugs :)

To summarize:

1. Do not use O_DIRECT_NO_FSYNC value for innodb_flush_method if your redo logs are located on different device than your data files. Just don't.
2. Some Oracle engineers who process bugs still do not care to check if all supported major versions are affected and/or share the results of such checks in public.
3. There are still many details of InnoDB locking to study, document properly and maybe fix.
4. I am really concerned with the state of MySQL optimizer. We see all kinds of weird bugs (including regressions) and very few fixes in each maintenance release.

Fun with Bugs #84 - On Some Public Bugs Fixed in MySQL 5.7.26

Oracle released minor MySQL Server versions in all supported branches on April 25, 2019. MySQL 5.7.26 is just one of them, but recently I prefer to ignore MySQL 8 releases (after checking that I can build them from source code at least somewhere, even if it takes 18G+ of disk space and that they work in basic tests), as there are more chances for MySQL 5.7 bug fixes to affect me (and customers I care about) directly.

So, in this yet another boring blog post (that would never be a reason for any award) I plan to concentrate on bugs reported in public MySQL bugs database and fixed in MySQL 5.7.26. As usual I name bug reporters explicitly and give links to their remaining currently active bug reports, if any. This time the list is short enough, so I do not even split it by categories:

• Bug #93164 - "Memory leak in innochecksum utility detected by ASan". This bug was reported by Yura Sorokin from Percona, who also had contributed a patch (for some reason this is not mentioned in the official release notes).
• Bug #90402 - "innodb async io error handling in io_event". Wei Zhao found yet another case when wrong data type was used in the code and I/O error was not handled, and this could lead even to crashes. He had submitted a patch.
• Bug #89126 - "create table panic on innobase_parse_hint_from_comment". Nice bug report with a patch from Yan Huang. Note also detailed analysis and test case provided by Marcelo Altmann in the comment. It's a great example of cooperation of all sides: Oracle MySQL developers, bugs verification team, bug reporter and other community users.
• Bug #92241 - "alter partitioned table add auto_increment diff result depending on algorithm". Yet another great finding from Shane Bester himself!
• Bug #94247 - "Contribution: Fix fractional timeout values used with WAIT_FOR_EXECUTED_GTI ...". This bug report was created based on pull request from Dirkjan Bussink, who had suggested a patch to fix the problem. Note the comment from Shlomi Noach that refers to Bug #94311 (still private).
• Bug #85158 - "heartbeats/fakerotate cause a forced sync_master_info". Note MTR test case contributed by Sveta Smirnova and code analysis in a comment from Vlad Lesin (both from Percona at that time) in this bug report from Trey Raymond.
• Bug #92690 - "Group Replication split brain with faulty network". I do not care about group replication (I have enough Galera in my life instead), but I could not skip this report by Przemyslaw Malkowski from Percona, with detailed steps on how to reproduce. Note comments from other community members. Yet another case to show that good bug reports attract community feedback and are fixed relatively fast.
• Bug #93750 - "Escaping of column names for GRANT statements does not persist in binary logs". Clear and simple bug report from Andrii Ustymenko. I wonder why it was not found by internal testing/QA. Quick test shows that MariaDB 10.3.7, for example, is not affected:
  

  c:\Program Files\MariaDB 10.3\bin>mysql -uroot -proot -P3316 test
  Welcome to the MariaDB monitor.  Commands end with ; or \g.
  Your MariaDB connection id is 9
  Server version: 10.3.7-MariaDB-log mariadb.org binary distribution
  
  Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
  
  Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
  
  MariaDB [test]> create table t_from(id int primary key, `from` int, c1 int);
  Query OK, 0 rows affected (0.582 sec)
  
  MariaDB [test]> create user 'user01'@'%' identified by 'user01';
  Query OK, 0 rows affected (0.003 sec)
  
  MariaDB [test]> grant select (`id`,`from`) on `test`.`t_from` to 'user01'@'%';
  Query OK, 0 rows affected (0.054 sec)
  
  MariaDB [test]> show master status;
  +------------------+----------+--------------+------------------+
  | File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
  +------------------+----------+--------------+------------------+
  | pc-PC-bin.000007 |      852 |              |                  |
  +------------------+----------+--------------+------------------+
  1 row in set (0.030 sec)
  
  MariaDB [test]> show binlog events in 'pc-PC-bin.000007';
  +------------------+-----+-------------------+-----------+-------------+--------
  -------------------------------------------------------------------+
  | Log_name         | Pos | Event_type        | Server_id | End_log_pos | Info
                                                                     |
  +------------------+-----+-------------------+-----------+-------------+--------
  -------------------------------------------------------------------+
  | pc-PC-bin.000007 |   4 | Format_desc       |         1 |         256 | Server
  ver: 10.3.7-MariaDB-log, Binlog ver: 4                             |
  | pc-PC-bin.000007 | 256 | Gtid_list         |         1 |         299 | [0-1-42
  ]                                                                  |
  | pc-PC-bin.000007 | 299 | Binlog_checkpoint |         1 |         342 | pc-PC-b
  in.000007                                                          |
  ...
  | pc-PC-bin.000007 | 708 | Query             |         1 |         852 | use `te
  st`; grant select (`id`,`from`) on `test`.`t_from` to 'user01'@'%' |
  +------------------+-----+-------------------+-----------+-------------+--------
  -------------------------------------------------------------------+
  9 rows in set (0.123 sec)

• Bug #73936 - "If the storage engine supports RBR, unsafe SQL statementes end up in binlog". Nice bug report with MTR test case by Santosh Praneeth Banda. Note that last comment about the fix mentions only MySQL 8.0.15, not a single work about the fix in MySQL 5.7.26 (or anything about MySQL 5.6.x while the bug was reported for 5.6).
• Bug #93341 - "Check for tirpc needs improvement". The need for improvement of CMake check was noted by Terje Røsten.
• Bug #91803 - "mysqladmin shutdown does not wait for MySQL to shut down anymore". This regression bug (without a "regression" tag) was reported by Christian Roser.
• Bug #91541 - ""Flush status" statement adds twice to global values ". Yura Sorokin contributed a detailed anlysis, MTR test case and a patch in this bug reported by Carlos Tutte.
• Bug #90351 - "GLOBAL STATUS variables drift after rollback". Zsolt Parragi contibuted a patch to this bug found and reported by Iwo P. For some reason this contribution is not highlighted in the release notes.
• Bug #81441 - "Warning about localhost when using skip-name-resolve". One of many bug reports from Monty Solomon in which he (and other community members like Jean-François Gagné) had to spend a lot of efforts and fight with a member of bugs verification team to get the bug accepted as a real code bug and then get it fixed in all versions affected.
• Bug #90902 - "Select Query With Complex Joins Leaks File Handles". This bug was reported by James Wilson. I still wonder if MySQL 5.6 was affected. Bug reports says nothing about this (while I expect all supported GA versions to be checked when the bug is verified, and the results of such check clearly documented).

The future looks bright for MySQL 5.7

To summarize:

1. Consider upgrade to 5.7.26 if you use complex joins, partitioned tables with auto_increment columns or rely on InnoDB or replication a lot.
2. It's good to see crashing bugs that do not end up as hidden/"security", maybe because they are reported with patches...
3. It's good to see examples of cooperation of several community users contributing to the same bug report!
4. Percona engineers contribute a lot to MySQL, both in form of bug reports, patches and by helping other community users to make their point and get their bugs fixed fast.
5. There are still things to improve in a way Oracle egnineers handle bugs verification, IMHO.
6.  It's also a bit strange to see only one optimizer-related fix in this release. It means that either MySQL optimizer is already near perfect and there are no bugs to fix (check yourself, but I see 123 bugs here), or that nobody cares that much about MySQL optimizer in 5.7 these days.
7. It seems for some bugs fixed in previous MySQL 8.0.x minor release there is no extra check/updates in public comments about the versions with the fix when it is released in MySQL 5.6 or 5.7.

Fun with Bugs #78 - On Some Public Bugs Fixed in MySQL 5.7.25

Today I'd like to continue my tradition of ignoring MySQL 8 (after all, I can not even build 8.0.14 any more on my Ubuntu 14.04, it's not supported suddenly because of old gcc version) and, of all MySQL server versions released by Oracle this week, concentrate on bugs reported in public bugs database and fixed in the latest minor release of MySQL 5.7 branch, 5.7.25.

This time there is only one InnoDB community-reported bug fixed, Buig #87423 - "os0file.cc assertion failed 'offset > 0' in os_file_io_complete", from Vasily Nemkov. See also it's duplicate, Bug #88956, by Aidan Diffey. Assertion failure seems to happen with 32-bit binaries running on 64-bit OS (both bugs are reported on Linux) and is related to infamous ulint type usage in the code, but for some reason release notes and closing comment mention Windows:

"An assertion was raised when attempting to write to a tablespace file greater than 4GB in size on a 64-bit Windows system. The failure was due to a narrowing cast."

Usually there are some bugs around flowers. But sometimes we can enjoy flowers without bugs...

There is a long enough list of replication bugs fixed:

• Bug #92132 - "secure-file-priv breaks LOAD DATA INFILE replication in statement mode on 5.7.23". This regression bug (that had not got "regression" tag!) was reported by Nicolai Plum.
• Bug #91941 - "Deadlock during purge_logs_before_date". Great bug report from Nikolai Ikhalainen. Note also that some hints by Jean-François Gagné and proper gdb backtrace analysis by Oracle engineers, Shane Bester and Dmitry Lenev, were needed to force proper processing of this bug. See also related Bug #92108 - "Deadlock by concurrent show binlogs, pfs session_variables table & binlog purge", from Shashank Sahni.
• Bug #91548 - "LOCK_grant and LOCK_open can deadlock on a gtid slave". Great example of Shane Bester's regular work on bugs.
• Bug #90640 - "`head->variables.gtid_next.type != UNDEFINED_GTID' ". One of those cases when assertion failure in debug build highlights real problem in the code. Great finding by Roel Van de Paar.
• Bug #87832 - "Relay_Log_Space is inaccurate and leaks". Nice bug report by Manuel Ung. Related variable could be changed concurrently without any locking and get randomly wrong values.
• Bug #84752 - "Multi-Slave Replication Fail: bogus data in log event". This bug was reported by Gonzalo Miguel Arruti . Eventually it seems internally reported Bug#22252394 - SLAVE I/O THREAD MAY STOP WHEN BINLOG ROTATES highlighted the real problem. Good to have this case fixed!
• Bug #83003 - "Using temporary tables on slaves increases GTID sequence number". I am so happy to this bug reported by my former colleague Ovais Tariq fixed in 5.7! Patches provided by Laurynas Biveinis from Percona are finally backported. It's so sad to see slaves out of sync with master when GTIDs are used... For some reason this bug is not listed as replication-related and patches contributed are not mentioned in the release notes.

Some other fixes are also interesting to check:

• Bug #92131  - "ASan: Direct leak of 272 byte(s) in main.mysqlpump_partial_bkp MTR test case". I mentioned this bug reported by Yura Sorokin from Percona in the past. Good to see it fixed. I truly hope Oracle is testing ASan builds regularly with MTR and we'll not see such reports from community any more. For now efforts of Percona engineers help, as we can see also from Bug #90238 - "Comparison of uninitailized memory in log_in_use" with patches from Zsolt Parragi and Laurynas Biveinis.
• Bug #92049 - "bogus data when ordering results from variables_by_thread". Thanks to Shane Bester from Oracle (who still reports MySQL bugs in public), we have one bug less in otherwise near perfect Performance Schema.
• Bug #90742 = "SIGHUP cause mysql server crash.". It was reported by Seunguck Lee. Good to see S1 crashing bug not blindly classified as "security" and hidden forever. Note also great analysis there provided by Jean-François Gagné! It would be impossible for any hidden bug to get this kind of useful feedback.
• Bug #89214 - "The SELECT will deadlock in the stored procedure, if the result set is empty.". It took some time and efforts for bug reporter (two pg) to prove the point, confirm that the problem happens only with prepared statements and force proper processing. This regression bug (MySQL 5.6 was not affected) still does not have "regression" tag.

That's all bugs I wanted to mention today. To summarize:

1. I'd surely consider immediate upgrade to 5.7.25 in any environment where replication is used.
2. It seems Oracle engineers who process bugs still have no habit of adding "regression" tag when obviously needed. I'll ask bug reporters to do this themselves during my FOSDEM talk about MySQL bugs.
3. Percona still helps Oracle to make MySQL better with proper QA efforts and patches.
4. Most of the bugs mentioned here affected MySQL 8 as well, so from this post you know about many important fixes that happened in MySQL 8.0.14 :) 

Fun with Bugs #75 - On MySQL Bug Reports I am Subscribed to, Part XII

From the lack of comments to my previous post it seems everything is clear with ERROR 1213 in different kinds and forks of MySQL. I may still write a post of two about MyRocks or TokuDB deadlocks one day, but let's get back to my main topic of MySQL bugs. Today I continue my series of posts about community bug reports I am subscribed to with a review of bugs reported in November, 2018, starting from the oldest and skipping those MySQL 8 regression ones I've already commented on. I also skip documentation bugs that should be a topic for a separate post one day (to give more illustration to these my statements).

These are the most interesting bug reports from Community members in November 2018:

• Bug #93139 - "mysqldump temporary views missing definer". This bug reported by Nikolai Ikhalainen from Percona looks like a regression (that can appear in a bit unusual case of missing root user) in all versions starting from 5.6. There is no regression tag, surely. Also for some reason I do not see 8.0.x as affected version, while from the text it seems MySQL 8 is also affected.
• Bug #93165 - "Memory leak in sync_latch_meta_init() after mysqld shutdown detected by ASan". This bug was reported by Yura Sorokin from Percona, who also made important statement in his last comment (that I totally agree with):
  

  "In commit https://github.com/mysql/mysql-server/commit/e93e8db42d89154b37f63772ce68c1efda637609 you literally made 14 MTR test cases ignore ALL memory problems detected by ASan, not only those which you consider 'OK' when you terminate the process with the call to 'exit()'. In other words, new memory leaks introduced in FUTURE commits may not be detected because of those changes. Address Sanitizer is a very powerful tool and its coverage should be constantly extending rather than shrinking."

• Bug #93196 - "DD crashes on assert if ha_commit_trans() returns error". It seems Vlad Lesin from Percona spent notable time testing everything related to new MySQL 8 data dictionary (maybe while Percona worked on their Percona Server for MySQL 8.0 that should have MyRocks also supported, should be able to provide native partitioning and proper integration with data dictionary). See also his Bug #93250 - "the result of tc_log->commit() is ignored in trans_commit_stmt()".
• Bug #93241 - "Query against full text index with ORDER BY silently fails". Nice finding by Jonathan Balinski, with detailed test cases and comments added by Shane Bester. One more confirmation that FULLTEXT indexes in InnoDB are still problematic.
• Bug #93276 - "Crash when calling mysql_real_connect() in loop". Nice regression in C API (since 8.0.4!) noted by Reggie Burnett and still not fixed.
• Bug #93321 - "Assertion `rc == TYPE_OK' failed". The last but not the least, yet another debug assertion (and error in non-debug build) found in MySQL 8.0.13 by Roel Van de Paar from Percona. You already know where QA for MySQL happens to large extent, don't you?
• Bug #93361 - "memory/performance_schema/table_handles have memory leak!". It's currently in "Need Feedback" status and may end up as not a bug, but I've never seen 9G of memory used for just one Performance Schema table so far. It's impressive.
• Bug #93365 - "Query on performance_schema.data_locks causes replication issues". Probably the first case when it was proved that query to some Performance Schema table may block some important server activity. Nice finding by Daniël van Eeden.
• Bug #93395 - "ALTER USER succeeds on master but fails on slave." Yet another way to break replication was found by Jean-François Gagné. See also his Bug #93397 - "Replication does not start if restart MySQL after init without start slave."
• Bug #93423 - "binlog_row_image=full not always honored for binlog_format=MIXED". For some reason this bug (with a clear test case) reported by James Lawrie is still "Open".
• Bug #93430 - "Inconsistent output of SHOW STATUS LIKE 'Handler_read_key';". This weird inconsistency was found by Przemysław Skibiński from Percona.

Thinking about the future of MySQL 8 somewhere in Greenwich...

To summarize this review:

1. I obviously pay a lot of attention to bug reports from Percona engineers.
2. It seems memory problems detected by ASan in some MTR test cases are deliberately ignored instead of being properly fixed.
3. There are still many surprises waiting for early adopters of MySQL 8.0 GA :) 

That's all I have to say about specific MySQL bugs in 2018. Next "Fun with Bugs" post, if any, will appear only next year. I am already subscribed to 11 bugs reported in December 2018. Stay tuned!

Fun with Bugs #73 - On MySQL Bug Reports I am Subscribed to, Part X

It's time to continue my review of MySQL bug reports that I considered interesting for some reason recently. I had not got any notable reaction from Oracle engineers to my previous post about recent regression bugs in MySQL 8.0.13, so probably this topic is not really that hot. In this boring post I'll just review some bugs I've subscribed to since August that are still not closed, starting from the oldest.

Let me start with a couple of bug reports that remain "Open":

• Bug #91959 - "UBSAN: signed integer overflow in lock_update_trx_age". It's really unusual to see bug reported by Shane Bester himself just "Open" for months. As he noted, it's really strange to see age defined as 32-bit value here when age_updated two lines later is 64-bit. On the other hand, from comments in the code it seems the age value is supposed to be small enough and if it grows too much this is a problem.
• Bug #92964 - "Slave performance degrades over time". As description says:
  

  "When mysql slave is running gtid based asynchronous multi threaded replication, performance degrades over time in significant way when session_track_gtids is set to OWN_GTID; "

  The bug is assigned, but there are no public comments, while the way to reproduce seem to be defined clearly.

Same as the weather at Seven Sisters Cliffs back on September 14, 2018, some recent MySQL bug reports do not add confidence to those few visitors who explore them...

Now let me continue with some "Verified" bugs:

• Bug #91981 - "Inconsistent user@host definitions for definer/grantor/grantee columns". It seems consistency is not a high priority these days.
• Bug #92020 - "Introduce new SQL mode rejecting queries with results depending on query plan". I already mentioned this report while reviewing recent MySQL optimizer bugs. I have nothing to add to my conclusion there:
  

  "So, current MySQL considers different results when different execution plans are used normal!"

• Bug #92032 - "Restrict usage of session foreign_key_checks". It's a great request from Federico Razzoli and I am happy to see it verified as a bug, fast.
• Bug #92093 - "Replication crash safety needs relay_log_recovery even with GTID." Recently Jean-François Gagné pays special attention to MySQL replication crash safety in his bug reports, talks and blog posts. This specific report ended up as a request for a more clear documentation that should not provoke (false) safety feelings. See also his Bug #92109 - "Please make replication crash safe with GTID and less durable setting (bis)." for the request to improve MySQL in this regard one day.
• Bug #92131 - "ASan: Direct leak of 272 byte(s) in main.mysqlpump_partial_bkp MTR test case". This kind of reports make me nervous. They make me think that still there is no regular testing of ASan-enabled builds in Oracle. Lucky we are, Percona engineers (like Yura Sorokin) do this for Oracle.
• Bug #92133 - "DICT_SYS mutex contention causes complete stall when running with 40 mill tables". Proper data dictionary in MySQL 8.0 was supposed to solve some performance problems for instances with a lot of tables. As this perfect bug report from Alexander Rubin shows, this is not yet the case. We can still push MySQL instance over the limits and single instance for thousands of different small databases is hardly usable.
• Bug #92209 - "AVG(YEAR(datetime_field)) makes an error result because of overflow". Perfect analysis from Pin Lin. All recent MySQL (and MariaDB) versions are affected.
• Bug #92252 - "Mysql generates gtid gaps because of option slave-skip-errors". Yet another bug report from Pin Lin. 
• Bug #92364 - "events_transactions_summary_global_by_event_name not working as expected". This bug was reported by Przemyslaw Malkowski from Percona. We all know Performance Schema is near perfect, but it turned out that "...performance_schema.events_transactions_summary_global_by_event_name behavior for instrumenting transactions seems completely broken.".
• Bug #92398 - "point in time recovery using mysqlbinlog broken with temporary table -> errors". Let me quote Shane Bester:
  

  "Running a multi-threaded workload involving temporary and non-temporary tables leads to binary log playback giving errors."

• Bug #92421 - "Queries with views and operations over local variables don't use indexes". This is a kind of regression in MySQL 5.7. MySQL 8 allows to workaround the problem properly using ROW_NUMBER() function.
• Bug #92540 - "Comparison between DATE and DECIMAL does not round nanoseconds". This bug was reported by Alexander Barkov from MariaDB. MariaDB 10.3.x is not affected based on my tests.

To summarize:

1. It seems ASan-enabled builds are not tested by Oracle engineers on a regular basis.
2. Percona engineers help a lot with regular MySQL QA and testing for various extreme use cases.
3. There is a lot to do to make GTID-based replication crash-safe and working fast in common use cases.

 More bug review are coming soon, so stay tuned.

On Oracle's QA for MySQL

In my recent blog posts I presented lists of bugs, fixed and not yet fixed, as usual. Working on these lists side tracked me from the main topic of this summer - problems in Oracle's way of handling MySQL. Time to get back on track!

Among things Oracle could do better for MySQL I mentioned QA:

"Oracle's internal QA efforts still seem to be somewhat limited.
We get regression bugs, ASAN failures, debug assertions, crashes, test failures etc in the official releases, and Oracle MySQL still relies a lot on QA by MySQL Community (while not highlighting this fact that much in public)."

I have to explain these in details, as it's common perception for years already that Oracle improved MySQL QA a lot and invests enormously in it, and famous MySQL experts were impressed even 5 years ago:

"Lets take a number we did get the QA team now has 400 person-years of experience on it. Lets say the QA team was 10 people before, and now it is tripled to 30 people. That means the average QA person has over 13 years experience in QA, which is about a year longer than my entire post-college IT career."

I was in the conference hall during that famous keynote, and QA related statements in it sounded mostly funny for me. Now, 5 years later, let me try to explain why just adding people and person-years of experience may not work that well. I'll try to present some examples and lists of bugs, as usual, to prove my points.

Emirates Air Line in London lets you see nice views of London, and it costed a lot, but hardly it's the most efficient public transport system between the North Greenwich Peninsula and Royal Victoria Dock one could imagine.

1. We still get all kinds of regression bugs reported by MySQL Community for every release, even MySQL 8.0.12. Here is the short list of random recent examples:
   
   • Bug #90209 - "Performance regression with > 15K tables in MySQL 8.0 (with general tablespaces)".
   • Bug #91878 - "Wrong results with optimizer_switch='derived_merge=OFF';".
   • Bug #91377 - "Can't Initialize MySQl if internal_tmp_disk_storage_engine is set to MYISAM".
   • Bug #90100 - "Year type column have index, query value more than 2156 , the result is wrong".
   • Bug #91927 - "8.0.12 no longer builds with Mac brew-installed ICU".
   • Bug #91975 - "InnoDB: Assertion failure: dict0dd.cc:1071:!fail".
   It means that Oracle's MySQL QA may NOT do enough/proper regression testing. We sometimes can not say this for sure, as Oracle hides some test cases. So, we, users of MySQL, just may not know what was the intention of some recent change (tests should show it even if the fine manual may not be clear enough - a topic for my next post).
   
2. We still get valid test failure bugs found by MySQL Community members. Some recent examples follows:
   
   • Bug #90633 - "innodb_fts.ngram_1 test fails (runs too long probably)".
   • Bug #90608 - "rpl_gtid.rpl_perfschema_applier_status_by_worker_gtid_skipped_transaction fails".
   • Bug #90631 - "perfschema.statement_digest_query_sample test fails sporadically".
   • Bug #89431 - "innodb_undo.truncate_recover MTR test failing with a server error log warning". It's fixed, but only in MySQL 8.0.13.
   • Bug #91175 - "rpl_semi_sync_group_commit_deadlock.test is not simulating flush error ".
   • Bug #91022 - "audit_null.audit_plugin_bugs test always failing".
   • Bug #86110 - "A number of MTR test cases fail when run on a server with no PERFSCHEMA".
   For me it means that Oracle's MySQL QA either do not care to run regression tests suite properly, in enough combination of platforms, options and build types, or they do not analyze the failures they get properly (and release when needed, not when all tests pass on all platforms). This is somewhat scary.
   
3. We still get crashing bugs in GA releases. It's hard to notice them as they are got hidden fast or as soon as they get public attention, but they do exist, and the last example, Bug #91928, is discussed here.
   
4. It seems some tools that helps to discover code problems may not be used properly/regularly in Oracle. I had a separate post "On Bugs Detected by ASan", where you can find some examples. Lucky we are that Percona engineers test ASan builds of MySQL 5.7 and 8.0 regularly, for years, and contribute back public bug reports.
   
5. Oracle's MySQL QA engineers do not write much about their work in public recently. I can find some posts here and there from 2013 and 2014, but very few in recent years. One may say that's because QA engineers are working hard and have no time for blogging (unlike lazy annoying individual like me), but that's not entirely true. There is at least one Oracle engineer who does a lot of QA and makes a lot of information about his work public - Shane Bester - who is brave enough and cares enough to report MySQL bugs in public. Ironically, I doubt he has any formal relation to any of QA teams in Oracle!
   
6. A lot of real MySQL QA is still done by MySQL Community, while these efforts are not that much acknowledged recently (you usually get your name mentioned in the official release notes if you submitted a patch, but the fact that you helped Oracle by finding a real bug their QA missed is NOT advertised any more since last Morgan's "Community Release Notes" published 2 years ago). Moreover, only MySQL Community tries to make QA job popular and educate users about proper tools and approaches (Percona and Roel Van de Paar personally are famous for this).

To summarize, for me it seems that real MySQL QA is largely still performed by MySQL Community and in public, while the impact of hidden and maybe huge Oracle's investments in QA is way less clear and visible. Oracle's MySQL QA investments look like those into the Emirates Air Line cable car in London to me - the result is nice to have, but it's the most expensive cable system ever built with a limited efficiency for community as a public transport.

Fun with Bugs #70 - On MySQL Bug Reports I am Subscribed to, Part VIII

More than 2 months passed since my previous review of active MySQL bug reports I am subscribed to, so it's time to describe what I was interested in this summer.

Let's start with few bug reports that really surprised me:

• Bug #91893 - "LOAD DATA INFILE throws error with NOT NULL column defined via SET". The bug was reported yesterday and seem to be about a regression in MySQL 8.0.12 vs older versions. At least I have no problem to use such a way to generate columns for LOAD DATA with MariaDB 10.3.7.
• Bug #91847 - "Assertion `thread_ids.empty()' failed.". As usual, Roel Van de Paar finds funny corner cases and assertion failures of all kinds. This time in MySQL 8.0.12.
• Bug #91822 - "incorrect datatype in RBR event when column is NULL and not explicit in query". Ernie Souhrada found out that the missing column is given the datatype of the column immediately preceding it, at least according to mysqlbinlog output.
• Bug #91803 - "mysqladmin shutdown does not wait for MySQL to shut down anymore". My life will never be the same as before after this. How can we trust anything when even shutdown command is no longer works as expected? I hope this bug is not confirmed after all, it's still "Open".
• Bug #91769 - "mysql_upgrade return code is '0' even after errors". Good luck to script writers! The bug is still "Open".
• Bug #91647 - "wrong result while alter an event". Events may just disappear when you alter them. Take care!
• Bug #91610 - "5.7 or later returns an error on strict mode when del/update with error func". Here Meiji Kimura noted a case when the behavior of strict sql_mode differs in MySQL 5.6 vs never versions.
• Bug #91585 - "“dead” code inside the stored proc or function can significantly slow it down". This was proved by Alexander Rubin from Percona.
• Bug #91577 - "INFORMATION_SCHEMA.INNODB_FOREIGN does not return a correct TYPE". This is a really weird bug in MySQL 8.
• Bug #91377 - "Can't Initialize MySQl if internal_tmp_disk_storage_engine is set to MYISAM". It seems Oracle tries really hard to get rid of MyISAM by all means in MySQL 8 :)
• Bug #91203 - "For partitions table, deal with NULL with is mismatch with reference guide". All version affected. maybe manual is wrong, but then we see weird results in information_schema as well. So, let's agree for now that it's a "Verified" bug in partitioning...

As usual, I am interested in InnoDB-related bugs:

• Bug #91861 - "The buf_LRU_free_page function may leak some memory in a particular scenario". This is a very interesting bug report about the memory leak that happens when tables are compressed. It shows how to use memory instrumentation in performance_schema to pinpoint the leak. This bug report is still "Open".
• Bug #91630 - "stack-use-after-scope in innobase_convert_identifier() detected by ASan". Yura Sorokin from Percona had not only reported this problem, but also contributed a patch.
• Bug #91120 - "MySQL8.0.11: ibdata1 file size can't be more than 4G". Why nobody tries to do anything about this "Verified" bug reported 2 months ago?
• Bug #91048 - "ut_basename_noext now dead code". This was reported by Laurynas Biveinis.

Replication problems are also important to know about:

• Bug #91744 - "START SLAVE UNTIL going further than it should." This scary bug in cyclic replication setup was reported by  Jean-François Gagné 2 weeks ago and is still "Open" at the moment.
• Bug #91633 - "Replication failure (errno 1399) on update in XA tx after deadlock". On top of all other problems with XA transactions we have in MySQL, it seems that replication may break upon executing a row update immediately after a forced transaction rollback due to a deadlock being detected while in an XA transaction.

Some optimizer bugs also caught my attention:

• Bug #91486 - "Wrong column type , view , binary". We have a "Verified" regression bug here without a "regression" tag or exact versions checked. Well done, Sinisa Milivojevic!
• Bug #91386 - "Index for group-by is not used with primary key for SELECT COUNT(DISTINCT a)". Yet another case where a well known bug reporter, Monty Solomon, had  to apply enormous efforts to get it "Verified" as a feature request.
• Bug #91139 - "use index dives less often". A "Verified" feature request from Mark Callaghan.

The last but not the least, documentation bugs. We have one today (assuming I do not care that much about group replication):

• Bug #91074 - "INSTANT add column undocumented". It was reported by my former colleague in Percona, Jaime Crespo. The bug is still "Verified" as of now, but since MySQL 8.0.12 release I think it's no longer valid. I see a lot of related details here, for example. But nobody cares to close this bug properly and provide the links to manual that were previously missing.

That's all for today, folks! Stay tuned.

Fun with Bugs #63 - On Bugs Detected by ASan

Among other things Geir Hoydalsvik stated in his nice post yesterday:

 "We’ve fixed a number of bugs detected by UBsan and Asan."

This is indeed true, I already noted many related bugs fixed in recent MySQL 8.0.4. But I think that a couple of details are missing in the blog post. First of all, there still a notable number of bugs detected by ASan or noted in builds with ASan that remain "Verified". Second, who actually found and reported these bugs?

I decided to do a quick search and present my summary to clarify these details. Let me start with the list of "Verified" or "Open" bugs in public MySQL bugs database, starting from the oldest one:

• Bug #69715 - "UBSAN: Item_func_mul::int_op() mishandles 9223372036854775809*-1". The oldest related "Verified" bug I found was reported back in 2013 by Arthur O'Dwyer. Shane Bester from Oracle kindly keeps checking it with recent and upcoming releases, so we know that even '9.0.0-dmr-ubsan' (built on 20 October 2017) was still affected.
• Bug #80309 - "some innodb tests fail with address sanitizer (WITH_ASAN)". It was reported by Richard Prohaska and remains "Verified" for more than two years already.
• Bug #80581 - "rpl_semi_sync_[non_]group_commit_deadlock crash on ASan, debug". This bug reported by Laurynas Biveinis from Percona two years ago is still "Verified".
• Bug #81674 - "LeakSanitizer-enabled build fails to bootstrap server for MTR". This bug reported by  Laurynas Biveinis affects only MySQL 5.6, but still, why not to backport the fix from 5.7?
• Bug #82026 - "Stack buffer overflow with --ssl-cipher=<more than 4K characters>". Bug detected by ASan was noted by Yura Sorokin from Percona and reported by Laurynas Biveinis.
• Bug #82915 - "SIGKILL myself when using innodb_limit_optimistic_insert_debug=2 and drop table". ASan debug builds are affected. This bug was reported by Roel Van de Paar from Percona.
• Bug #85995 - "Server error exit due to empty datadir causes LeakSanitizer errors". This bug in MySQL 8.0.1 (that had to affect anyone who runs tests on ASan debug builds on a regular basis) was reported by Laurynas Biveinis and stay "Verified" for almost a year.
• Bug #87129 - "Unstable test main.basedir". This test problem reported by Laurynas Biveinis affects ASan builds, among others. See also his Bug #87190 - "Test main.group_by is unstable".
• Bug #87201 - "XCode 8.3.3+ -DWITH_UBSAN=ON bundled protobuf build error". Yet another (this time macOS-specific) bug found by Laurynas Biveinis.
• Bug #87295 - "Test group_replication.gr_single_primary_majority_loss_1 produces warnings". Potential bug in group replication noted by Laurynas Biveinis in ASan builds.
• Bug #87923 - "ASan reporting a memory leak on merge_large_tests-t". This bug by Laurynas Biveinis is still "Verified", while Tor Didriksen's comment states that it it resolved with the fix for Bug #87922 (that is closed as fixed in MySQL 8.0.4). Why not to close this one also?
• Bug #89438 - "LeakSanitizer errors on xplugin unit tests". As Laurynas Biveinis found, X Plugin unit tests report errors with LeakSanitizer.
• Bug #89439 - "LeakSanitizer errors on GCS unit tests". yet another bug report for MySQL 8.0.4 by Laurynas Biveinis.
• Bug #89961 - "add support for clang ubsan". This request was made by Tor Didriksen from Oracle. It is marked as "fixed in 8.0.12". It means we may get MySQL 8.0.11 released soon. That's why I decided to mention the bug here.

There were also few other test failures noted on ASan debug builds. I skipped them to make this post shorter.

Personally I do not run builds or tests with ASan on a regular basis. I appreciate Oracle's efforts to make code warning-free, UBSan- and ASan-clean, and fix bugs found with ASan. But I'd also want them to process all/most of related bugs in public database properly before making announcements of new related achievement, and clearly admit and appreciate a lot of help and contribution from specific community members (mostly Laurynas Biveinis in this case).

Percona engineers seem to test ASan builds of MySQL 5.7 and 8.0 (or Percona's closely related versions) regularly, for years, and contribute back public bug reports. I suspect they found way more related bugs than internal Oracle's QA. I think we should explicitly thank them for this contribution that made MySQL better!