Oct
06
2021
--

Reminder: TokuDB Storage Engine Will Be Disabled by Default in Percona Server for MySQL 8.0.26

TokuDB Disabled in Percona Server for MySQL

TokuDB Disabled in Percona Server for MySQLAs we’ve communicated in our blog post in May, the TokuDB Storage Engine has been marked as “deprecated” in Percona Server for MySQL 8.0. It will be removed in a future version (Percona Server for MySQL 8.0.28, expected to ship in Q1 2022).

With the release of Percona Server for MySQL 8.0.26, the storage engine will still be included in the binary builds and packages but will be disabled by default. If you are upgrading from a previous version, the TokuDB Storage Engine plugin will fail with an error message at server startup if it is installed.

You will still be able to re-enable it manually so that you can perform the necessary migration steps.

Re-enabling the TokuDB Engine in Percona Server for MySQL 8.0.26 is fairly straightforward. You need to add the options

tokudb_enabled=TRUE

and

tokudb_backup_enabled=TRUE

options to your my.cnf file and restart your server instance.

Once the server is up and running again, you can migrate your data to an alternative storage engine like RocksDB or InnoDB before disabling and removing TokuDB. See the chapter Removing the TokuDB storage engine in our documentation for details.

Let us know if you have any questions or comments about this process!

If you need any assistance with migrating your data or have any questions or concerns about this, don’t hesitate to reach out to us – our experts are here to help!

Complete the 2021 Percona Open Source Data Management Software Survey

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May
21
2021
--

Heads-Up: TokuDB Support Changes and Future Removal from Percona Server for MySQL 8.0

TokuDB Support Changes

TokuDB Support ChangesBack in December 2018, when we announced the general availability of Percona Server for MySQL 8.0, we also announced that the TokuDB Storage Engine has been marked as “deprecated” in this release, recommending to use the MyRocks Storage Engine as an alternative. We believe that MyRocks provides similar benefits for the majority of workloads and is better optimized for modern hardware.

Since then, we have continued maintaining the storage engine in the 8.0 release, e.g. by incorporating bug fixes. However, the ongoing amount of changes that are still occurring in the upstream MySQL 8.0 codebase have been a constant challenge and a cause for concern.

Maintaining TokuDB as part of the 8.0 codebase has become increasingly difficult and time-consuming. Based on the number of support requests and conversations on our forums, we have seen very little to no adoption of TokuDB in Percona Server for MySQL 8.0.

We have therefore decided that the TokuDB storage engine will be disabled in future versions of Percona Server for MySQL 8.0. Beginning with Percona Server version 8.0.25, we’ll add a respective warning notice to the release notes, to inform users about this upcoming change.

Timeline

Starting with Percona Server version 8.0.26 (expected in Q3 2021), the storage engine will still be included in the binary builds and packages, but disabled by default. Users upgrading from previous versions will still be able to re-enable it manually, so they can perform the necessary migration steps.

Starting with Percona Server for MySQL version 8.0.28 (expected to ship in Q1 2022), the TokuDB storage will no longer be supported and will be removed from the installation packages. It will still be part of the 8.0 source code, but not enabled in our binary builds.

We intend to fully remove it in the next major version of Percona Server for MySQL (9.0 or whatever version that will be). Note that this change only applies to Percona Server for MySQL version 8.0 – TokuDB remains enabled and supported in Percona Server 5.7 until this release has reached the end of its support period.

In case you’re still using TokuDB in Percona Server 8.0, we recommend switching to InnoDB or MyRocks instead as soon as possible. Please consult our documentation on how to migrate and remove the TokuDB storage engine.

If you need any assistance with migrating your data or if you have any questions or concerns about this, don’t hesitate to reach out to us – our experts are here to help!

May
31
2018
--

Percona Server for MySQL 5.7.22-22 Is Now Available

Percona Server for MySQL

Percona Server for MySQLPercona announces the GA release of Percona Server for MySQL 5.7.22-22 on on May 31, 2018. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository.

Based on MySQL 5.7.22, including all the bug fixes in it, Percona Server for MySQL 5.7.22-22 is the current GA release in the Percona Server for MySQL 5.7 series. Percona provides completely open-source and free software.

New Features:
  • A new --encrypt-tmp-files option turns on encryption for the temporary files which Percona Server may create on disk for filesort, binary log transactional caches and Group Replication caches.
Bugs Fixed:
  • Executing the SHOW GLOBAL STATUS expression could cause “data drift” on global status variables in case of a query rollback: the variable, being by its nature a counter and allowing only an increase, could return to its previous value. Bug fixed #3951 (upstream #90351).
  • NUMA support was improved in Percona Server, reverting upstream implementation back to the original one,due to upstream variant being less effective in memory allocation. Now  innodb_numa_interleave variable not only enables NUMA interleave memory policy for the InnoDB buffer pool allocation, but forces NUMA interleaved allocation at the buffer pool initialization time. Bug fixed #3967.
  • audit_log_include_accounts variable did not take effect if placed in my.cnf configuration file, while still working as intended if set dynamically. Bug fixed #3867.
  • key_block_size value was set automatically by the Improved MEMORY Storage Engine, which resulted in warnings when changing the engine type to InnoDB, and constantly growing key_block_size during alter operations. Bugs fixed #3936#3940, and #3943.
  • Fixes were introduced to remove GCC 8 compilation warnings for the Percona Server build. Bug fixed #3950.
  • An InnoDB Memcached Plugin code clean-up was backported from MySQL 8.0. Bug fixed  #4506.
  • Percona Server could not be built with -DWITH_LZ4=system option on Ubuntu 14.04 (Trusty) because of too old LZ4 packages. Bug fixed #3842.
  • A regression brought during TokuDB code clean-up in 5.7.21-21 was causing assertion in cases when the FT layer returns an error during an alter table operation. Bug fixed #4294.
MyRocks Changes and fixes:
  • UPDATE statements were returning incorrect results because of not making a full table scan on tables with unique secondary index. Bug fixed #4495 (upstream facebook/mysql-5.6#830).
Other Bugs Fixed:
  • #4451 “Implement better compression algo testing”
  • #4469 “variable use out of scope bug in get_last_key test detected by ASAN in clang 6”
  • #4470 “the cachetable-simple-pin-nonblocking-cheap test occasionally fails due to a locking conflict with the cachetable evictor”
  • #4488 “-Werror is always disabled for innodb_memcached
  • #1114 “Assertion `inited == INDEX’ failed”
  • #1130 “RBR Replication with concurrent XA in READ-COMMITTED takes supremum pseudo-records and breaks replication”

Find the release notes for Percona Server for MySQL 5.7.22-22 in our online documentation. Report bugs in the Jira bug tracker.

The post Percona Server for MySQL 5.7.22-22 Is Now Available appeared first on Percona Database Performance Blog.

Mar
27
2018
--

ANALYZE TABLE Is No Longer a Blocking Operation

analyze table

analyze tableIn this post, I’ll discuss the fix for lp:1704195 (migrated to PS-2503), which prevents

ANALYZE TABLE

 from blocking all subsequent queries on the same table.

In November 2017, Percona released a fix for lp:1704195 (migrated to PS-2503), created by Laurynas Biveinis. The fix, included with Percona Server for MySQL since versions 5.6.38-83.0 and 5.7.20-18, stops

ANALYZE TABLE

 from invalidating query and table definition cache content for supported storage engines (InnoDB, TokuDB and MyRocks).

Why is this important?

In short, it is now safe to run

ANALYZE TABLE

 in production environments because it won’t trigger a situation where all queries on the same table stack are in the state

"Waiting for table flush"

. Check this blog post for details on how this situation can happen.

Why do we need to run ANALYZE TABLE?

When Optimizer decides which index to choose to resolve the query, it uses statistics stored for this table by storage engine. If the statistics are not up to date, Optimizer might choose the wrong index when it creates the query execution plan. This can cause performance to suffer.

To prevent this, storage engines support automatic and manual statistics updates. While automatic statistics updates usually work fine, there are cases when they do not do their job properly.

For example, InnoDB uses 20 sample 16K pages when it updates persistent statistics, and eight 16K pages when it updates transient statistics. If your data distribution is even, it does not matter how big your table is: even for 1T tables, using a sample of 320K is enough. But if your data isn’t even, statistics might get wrongly created. The solution for this issue is to increase either the innodb_stats_transient_sample_pages or innodb_stats_persistent_sample_pages variable. But increasing the number of pages to examine while collecting statistics leads to longer update runs, and thus higher IO activity, which is probably not what you want to happen often.

To control this, you can disable automatic statistics updates for such tables, and schedule a job that periodically runs 

ANALYZE TABLE

.

Will it be safe before the fix for lp:1704195 (migrated to PS-2503)?

Theoretically yes, but we could easily hit a situation as described in this blog post by Miguel Angel Nieto. The article describes what if some long-running query starts and doesn’t finish before

ANALYZE TABLE

. All the queries on the analyzing table get stuck in the state

"Waiting for table flush"

 at some time.

This happens because before the fix, 

ANALYZE TABLE

 worked as follows:

  1. Opens table statistics: concurrent DML operations (
    INSERT/UPDATE/DELETE/SELECT

    ) are allowed

  2. Updates table statistics: concurrent DML operations are allowed
  3. Update finished
  4. Invalidates table entry in the table definition cache: concurrent DML operations are forbidden
    1. What happens here is
      ANALYZE TABLE

       marks the currently open table share instances as invalid. This does not affect running queries: they will complete as usual. But all incoming queries will not start until they can re-open table share instance. And this will not happen until all currently running queries complete.

  5. Invalidates query cache: concurrent DML operations are forbidden

Last two operations are usually fast, but they cannot finish if another query touched either the table share instance or acquired query cache mutex. And, in its turn, it cannot allow for incoming queries to start.

However

ANALYZE TABLE

 modifies table statistics, not table definition!

Practically, it cannot affect already running queries in any way. If a query started before

ANALYZE TABLE

 finished updating statistics, it uses old statistics.

ANALYZE TABLE

 does not affect data in the table. Thus old entries in the query cache will still be correct. It hasn’t changed the definition of the table. Therefore there is no need to remove it from the table definition cache. As a result, we avoid operations 4 and 5 above.

The fix for lp:1704195 (migrated to PS-2503) removes these additional updates and locks required for them, and makes

ANALYZE TABLE

 always safe to run in busy production environments.

The post ANALYZE TABLE Is No Longer a Blocking Operation appeared first on Percona Database Performance Blog.

Feb
19
2018
--

Percona Server for MySQL 5.7.21-20 Is Now Available

Percona Server for MySQL 5.7.20-18

Percona Server for MySQL 5.7.20-19Percona announces the GA release of Percona Server for MySQL 5.7.21-20 on February 19, 2018. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository.

Based on MySQL 5.7.21, including all the bug fixes in it, Percona Server for MySQL 5.7.21-20 is the current GA release in the Percona Server for MySQL 5.7 series. Percona provides completely open-source and free software.

New Features:
  • A new string variable version_suffix allows to change suffix for the Percona Server version string returned by the read-only version variable. Also version_comment is converted from a global read-only to a global read-write variable.
  • A new keyring_vault_timeout variable allows to set the amount of seconds for the Vault server connection timeout. Bug fixed #298.
Bugs Fixed:
  • mysqld startup script was unable to detect jemalloc library location for preloading, and that prevented starting Percona Server on systemd based machines. Bugs fixed #3784 and #3791.
  • There was a problem with fulltext search, which could find a word with punctuation marks in natural language mode only, but not in boolean mode. Bugs fixed #258#2501 (upstream #86164).
  • Build errors were present on FreeBSD (caused by fixing the bug #255 in Percona Server 5.6.38-83.0) and on MacOS (caused by fixing the bug #264 in Percona Server 5.7.20-19). Bugs fixed #2284 and #2286.
  • A bunch of fixes was introduced to remove GCC 7 compilation warnings for
    the Percona Server build. Bugs fixed #3780 (upstream #89420#89421, and #89422).
  • CMake error took place at compilation with bundled zlib. Bug fixed #302.
  • A GCC 7 warning fix introduced regression in Percona Server that led to a wrong SQL query built to access the remote server when Federated storage engine was used. Bug fixed #1134.
  • It was possible to enable encrypt_binlog with no binary or relay logging enabled. Bug fixed #287.
  • Long buffer wait times where occurring on busy servers in case of the IMPORT TABLESPACE command.
  • Bug fixed #276.
  • Server queries that contained JSON special characters and were logged by Audit Log Plugin in JSON format caused invalid output due to lack of escaping. Bug fixed #1115.
  • Percona Server now uses Travis CI for additional tests. Bug fixed #3777.

Other bugs fixed:  #257#264#1090  (upstream #78048),  #1109#1127#2204#2414#2415#3767#3794, and  #3804 (upstream #89598).

 This release also contains fixes for the following CVE issues: CVE-2018-2565, CVE-2018-2573, CVE-2018-2576, CVE-2018-2583, CVE-2018-2586, CVE-2018-2590, CVE-2018-2612, CVE-2018-2600, CVE-2018-2622, CVE-2018-2640, CVE-2018-2645, CVE-2018-2646, CVE-2018-2647, CVE-2018-2665, CVE-2018-2667, CVE-2018-2668, CVE-2018-2696, CVE-2018-2703, CVE-2017-3737.
MyRocks Changes:
  • A new behavior makes Percona Server fail to restart on detected data corruption;  rocksdb_allow_to_start_after_corruption variable can be passed to mysqld as a command line parameter to switch off this restart failure.
  • A new cmake option ALLOW_NO_SSE42 was introduced to allow MyRocks build on hosts not supporting SSE 4.2 instructions set, which makes MyRocks usable without FastCRC32-capable hardware. Bug fixed MYR-207.
  • rocksdb_bytes_per_sync  and rocksdb_wal_bytes_per_sync  variables were turned into dynamic ones.
  • rocksdb_flush_memtable_on_analyze variable has been removed.
  • rocksdb_concurrent_prepare is now deprecated, as it has been renamed in upstream to  rocksdb_two_write_queues.
  • rocksdb_row_lock_deadlocks and rocksdb_row_lock_wait_timeouts global status counters were added to track the number of deadlocks and the number of row lock wait timeouts.
  • Creating table with string indexed column to non-binary collation now generates warning about using inefficient collation instead of error. Bug fixed MYR-223.
TokuDB Changes:
  • A memory leak was fixed in the PerconaFT library, caused by not destroying PFS key objects on shutdown. Bug fixed TDB-98.
  • A clang-format configuration was added to PerconaFT and TokuDB. Bug fixed TDB-104.
  • A data race was fixed in minicron utility of the PerconaFT. Bug fixed TDB-107.
  • Row count and cardinality decrease to zero took place after long-running REPLACE load.

Other bugs fixed: TDB-48TDB-78TDB-93, and TDB-99.

The release notes for Percona Server for MySQL 5.7.21-20 are available in the online documentation. Please report any bugs on the project bug tracking system.

Feb
16
2018
--

This Week in Data with Colin Charles 28: Percona Live, MongoDB Transactions and Spectre/Meltdown Rumble On

Colin Charles

Colin CharlesJoin Percona Chief Evangelist Colin Charles as he covers happenings, gives pointers and provides musings on the open source database community.

In case you missed last week’s column, don’t forget to read the fairly lengthy FOSDEM MySQL & Friends DevRoom summary.

From a Percona Live Santa Clara 2018 standpoint, beyond the tutorials getting picked and scheduled, the talks have also been picked and scheduled (so you were very likely getting acceptance emails from the Hubb.me system by Tuesday). The rejections have not gone out yet but will follow soon. I expect the schedule to go live either today (end of week) or early next week. Cheapest tickets end March 4, so don’t wait to register!

Amazon Relational Database Service has had a lot of improvements in 2017, and the excellent summary from Jeff Barr is worth a read: Amazon Relational Database Service – Looking Back at 2017. Plenty of improvements for the MySQL, MariaDB Server, PostgreSQL and Aurora worlds.

Spectre/Meltdown and its impact are still being discovered. You need to read Brendan Gregg’s amazing post: KPTI/KAISER Meltdown Initial Performance Regressions. And if you visit Percona Live, you’ll see an amazing keynote from him too! Are you still using MyISAM? MyISAM and KPTI – Performance Implications From The Meltdown Fix suggests switching to Aria or InnoDB.

Probably the biggest news this week though? Transactions are coming to MongoDB 4.0. From the site, “MongoDB 4.0 will add support for multi-document transactions, making it the only database to combine the speed, flexibility, and power of the document model with ACID guarantees. Through snapshot isolation, transactions will provide a globally consistent view of data, and enforce all-or-nothing execution to maintain data integrity.”. You want to read the blog post, MongoDB Drops ACID (the title works if you’re an English native speaker, but maybe not quite if you aren’t). The summary diagram was a highlight for me because you can see the building blocks, plus future plans for MongoDB 4.2.

Releases

Link List

Upcoming appearances

  • SCALE16x – Pasadena, California, USA – March 8-11 2018
  • FOSSASIA 2018 – Singapore – March 22-25 2018

Feedback

I look forward to feedback/tips via e-mail at colin.charles@percona.com or on Twitter @bytebot.

Aug
31
2017
--

Percona Server for MySQL 5.7.19-17 Is Now Available

Percona Server for MySQL 5.7.18-15

Percona Server for MySQL 5.6Percona announces the release of Percona Server for MySQL 5.7.19-17 on August 31, 2017. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository.

Based on MySQL 5.7.19, and including all the bug fixes in it, Percona Server for MySQL 5.7.19-17 is now the current GA release in the Percona Server for MySQL 5.7 series. Percona Server for MySQL is open-source and free – this is the latest release of our enhanced, drop-in replacement for MySQL. Complete details of this release are available in the 5.7.19-17 milestone on Launchpad.

NOTE: Percona software no longer supports Red Hat Enterprise Linux 5 (including CentOS 5 and other derivatives), Ubuntu 12.04 and older versions. These platforms have reached end of life, won’t be updated and are not recommended for use in production.

 

New Features

  • Included the Percona MyRocks storage engine

    NOTE: MyRocks for Percona Server is currently experimental and not recommended for production deployments until further notice. You are encouraged to try it in a testing environment and provide feedback or report bugs.

  • #1708087: Added the mysql-helpers script to handle checking for missing datadir during startup. Also fixes #1635364.

Platform Support

  • Stopped providing packages for Ubuntu 12.04 due to its end of life.

Bugs Fixed

  • #1669414: Fixed handling of failure to set O_DIRECT on parallel doublewrite buffer file.
  • #1705729: Fixed the postinst script to correctly locate the datadir. Also fixes #1698019.
  • #1709811: Fixed yum upgrade to not enable the mysqld service if it was disabled before the upgrade.
  • #1709834: Fixed the mysqld_safe script to correctly locate the basedir.
  • Other fixes: #1698996#1706055#1706262#1706981

TokuDB Changes

  • TDB-70: Removed redundant fsync of TokuDB redo log during binlog group commit flush stage. This fixes issue that prevented TokuDB to run in reduced durability mode when the binlog was enabled.
  • TDB-72: Fixed issue when renaming a table with non-alphanumeric characters in its name.

Release notes for Percona Server for MySQL 5.7.19-17 are available in the online documentation. Please report any bugs on the launchpad bug tracker.

Aug
25
2017
--

Percona Server for MySQL 5.6.37-82.2 Is Now Available

Percona Server for MySQL 5.7.18-15

Percona Server for MySQL 5.6Percona announces the release of Percona Server for MySQL 5.6.37-82.2 on August 25, 2017. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository.

Based on MySQL 5.6.37, and including all the bug fixes in it, Percona Server for MySQL 5.6.37-82.2 is now the current GA release in the Percona Server for MySQL 5.6 series. Percona Server for MySQL is open-source and free – this is the latest release of our enhanced, drop-in replacement for MySQL. Complete details of this release are available in the 5.6.37-82.2 milestone on Launchpad.

NOTE: Red Hat Enterprise Linux 5 (including CentOS 5 and other derivatives), Ubuntu 12.04 and older versions are no longer supported by Percona software. The reason for this is that these platforms reached end of life, will not receive updates and are not recommended for use in production.

Bugs Fixed

  • #1703105: Fixed overwriting of error log on server startup.
  • #1705729: Fixed the postinst script to correctly locate the datadir.
  • #1709834: Fixed the mysqld_safe script to correctly locate the basedir.
  • Other fixes: #1706262

TokuDB Changes

  • TDB-72: Fixed issue when renaming a table with non-alphanumeric characters in its name.

Platform Support

  • Stopped providing packages for RHEL 5 (CentOS 5) and Ubuntu 12.04.

Release notes for Percona Server for MySQL 5.6.37-82.2 are available in the online documentation. Please report any bugs on the launchpad bug tracker.

Aug
18
2017
--

This Week in Data with Colin Charles: Percona Live Europe!

Colin Charles

Colin CharlesJoin Percona Chief Evangelist Colin Charles as he covers happenings, gives pointers and provides musings on the open source database community.

Has a week passed already? Welcome back to the second column. A lot of time has been spent neck deep in getting speakers accepted and scheduled for Percona Live Open Source Database Conference Europe 2017 in Dublin, as well organizing the conference sponsors.

Percona Live Europe Dublin

Percona Live Europe Colin CharlesAt the time of writing, we are six weeks away from the conference, so a little over a month! Have you registered yet?

We have 12 tutorials that cover a wide range of topics: ProxySQL (from the author Rene Cannao), Orchestrator (from the author Shlomi Noach), practical Couchbase (to name a few). If we did a technology word cloud, the coverage includes MongoDB, Docker, Elastic, Percona Monitoring and Management (PMM), Percona XtraDB Cluster 5.7, MySQL InnoDB Cluster and Group Replication.

In addition to that, if you’re a MySQL beginner (or thinking of a career change) there is a six-hour boot camp titled MySQL in a Nutshell (Part 1 and Part 2)!. Come prepared with your laptop, and leave a MySQL DBA!

Sessions are scheduled, and most of the content is already online: check out day 1, and day 2. We have 104 sessions scheduled, so there’s plenty to choose from.

Remember that you have till 7:00 a.m. UTC-1, August 16th, 2017 to book the group rate at the event venue for €250/night. Use code PERCON.

Releases

  • orchestrator/raft: Pre-release 3.0 is available. I’m a huge fan of Orchestrator, and now you can setup high availability for orchestrator via the Raft consensus protocol.
  • MariaDB 10.0.32 is out, and it comes with a new Percona XtraDB, Percona TokuDB and a new InnoDB. You’ll want this release if you’re using TokuDB, as it merges from TokuDB 5.6.36-82.1 (which fixes the two issues problem).
  • If you encountered the TokuDB problems above, you’ll want to look at MariaDB 10.1.26. One surprise hidden in the release notes: MariaDB Backup is now a stable/GA release. Have you used it yet?

Link List

I look forward to feedback/tips via e-mail at colin.charles@percona.com or I’m @bytebot on Twitter.

May
12
2017
--

Percona Server for MySQL 5.7.18-14 is Now Available

Percona Server for MySQL 5.7.18-14

Percona Server for MySQL 5.7.18-14Percona announces the GA release of Percona Server for MySQL 5.7.18-14 on May 12, 2017. Download the latest version from the Percona web site or the Percona Software Repositories. You can also run Docker containers from the images in the Docker Hub repository.

Based on MySQL 5.7.18, including all the bug fixes in it, Percona Server for MySQL 5.7.18-14 is the current GA release in the Percona Server for MySQL 5.7 series. Percona’s provides completely open-source and free software. Find release details in the 5.7.18-14 milestone at Launchpad.

New Features:
Bugs Fixed:
  • Deadlock could occur in I/O-bound workloads when server was using several small buffer pool instances in combination with small redo log files and variable innodb_empty_free_list_algorithm set to backoff algorithm. Bug fixed #1651657.
  • Fixed a memory leak in Percona TokuBackup. Bug fixed #1669005.
  • Compressed columns with dictionaries could not be added to a partitioned table by using ALTER TABLE. Bug fixed #1671492.
  • Fixed a memory leak that happened in case of failure to create a multi-threaded slave worker thread. Bug fixed #1675716.
  • In-place upgrade from Percona Server 5.6 to 5.7 by using standalone packages would fail if /var/lib/mysql wasn’t defined as the datadir. Bug fixed #1687276.
  • Combination of using any audit API-using plugin, like Audit Log Plugin and Response Time Distribution, with multi-byte collation connection and PREPARE statement with a parse error could lead to a server crash. Bug fixed #1688698 (upstream #86209).
  • Fix for a #1433432 bug caused a performance regression due to suboptimal LRU manager thread flushing heuristics. Bug fixed #1631309.
  • Creating Compressed columns with dictionaries in MyISAM tables by specifying partition engines would not result in error. Bug fixed #1631954.
  • It was not possible to configure basedir as a symlink. Bug fixed #1639735.
  • Replication slave did not report Seconds_Behind_Master correctly when running in multi-threaded slave mode. Bug fixed #1654091 (upstream #84415).
  • DROP TEMPORARY TABLE would create a transaction in binary log on a read-only server. Bug fixed #1668602 (upstream #85258).
  • Processing GTIDs in the relay log that were already been executed were causing write/fsync amplification. Bug fixed #1669928 (upstream #85141).
  • Text/BLOB fields were not handling sorting of the empty string consistently between InnoDB and filesort. Bug fixed #1674867 (upstream #81810) by porting a Facebook patch for MySQL.
  • InnoDB adaptive hash index was using a partitioning algorithm which would produce uneven distribution when the server contained many tables with an identical schema. Bug fixed #1679155 (upstream #81814).
  • For plugin variables that are signed numbers, doing a SHOW VARIABLES would always show an unsigned number. Fixed by porting a Facebook patch for MySQL.

Other bugs fixed: #1629250 (upstream #83245), #1660828 (upstream #84786), #1664519 (upstream #84940), #1674299, #1670588 (upstream #84173), #1672389, #1674507, #1675623, #1650294, #1659224, #1662908, #1669002, #1671473, #1673800, #1674284, #1676441, #1676705, #1676847 (upstream #85671), #1677130 (upstream #85678), #1677162, #1677943, #1678692, #1680510 (upstream #85838), #1683993, #1684012, #1684078, #1684264, #1687386, #1687432, #1687600, and #1674281.

The release notes for Percona Server for MySQL 5.7.18-14 are available in the online documentation. Please report any bugs on the launchpad bug tracker.

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