Release Candidate for Percona Server 8.0.12-2rc1 Is Available

Percona Server for MySQL

Following the alpha release announced earlier, Percona announces the release candidate of Percona Server for MySQL 8.0.12-2rc1 on October 31, 2018. Download the latest version from the Percona website or from the Percona Software Repositories.

This release is based on MySQL 8.0.12 and includes all the bug fixes in it. It is a Release Candidate quality release and it is not intended for production. If you want a high quality, Generally Available release, use the current Stable version (the most recent stable release at the time of writing in the 5.7 series is 5.7.23-23).

Percona provides completely open-source and free software.


As this is a release candidate, installation is performed by enabling the testing repository and installing the software via your package manager.  For Debian based distributions see apt installation instructions, for RPM based distributions see yum installation instructions.  Note that in both cases after installing the current percona-release package, you’ll need to enable the testing repository in order to install Percona Server for MySQL 8.0.12-2rc1.  For manual installations you can download from the testing repository directly through our website.

New Features

  • #4550: Native Partitioning support for MyRocks storage engine
  • #3911: Native Partitioning support for TokuDB storage engine
  • #4946: Add an option to prevent implicit creation of column family in MyRocks
  • #4839: Better default configuration for MyRocks and TokuDB
  • InnoDB changed page tracking has been rewritten to account for redo logging changes in MySQL 8.0.11.  This fixes fast incremental backups for PS 8.0
  • #4434: TokuDB ROW_FORMAT clause has been removed, compression may be set by using the session variable tokudb_row_format instead.


  • Several packaging changes to bring Percona packages more in line with upstream, including split repositories. As you’ll note from our instructions above we now ship a tool with our release packages to help manage this.

Bugs Fixed

  • #4785: Setting version_suffix to NULL could lead to handle_fatal_signal (sig=11) in Sys_var_version::global_value_ptr
  • #4788: Setting log_slow_verbosity and enabling the slow_query_log could lead to a server crash
  • #4947: Any index comment generated a new column family in MyRocks
  • #1107: Binlog could be corrupted when tmpdir got full
  • #1549: Server side prepared statements lead to a potential off-by-second timestamp on slaves
  • #4937: rocksdb_update_cf_options was useless when specified in my.cnf or on command line.
  • #4705: The server could crash on snapshot size check in RocksDB
  • #4791: SQL injection on slave due to non-quoting in binlogged ROLLBACK TO SAVEPOINT
  • #4953: rocksdb.truncate_table3 was unstable

Other bugs fixed:

  • #4811: 5.7 Merge and fixup for old DB-937 introduces possible regression
  • #4885: Using ALTER … ROW_FORMAT=TOKUDB_QUICKLZ leads to InnoDB: Assertion failure: ha_innodb.cc:12198:m_form->s->row_type == m_create_info->row_type
  • Numerous testsuite failures/crashes

Upcoming Features


The Importance of mysqlbinlog –version

Importance of MySQL binlog version

Importance of MySQL binlog versionWhen deciding on your backup strategy, one of the key components for Point In Time Recovery (PITR) will be the binary logs. Thankfully, the mysqlbinlog command allows you to easily take binary log backups, including those that would otherwise be encrypted on disk using encrypt_binlog=ON.



  is used with

--raw --read-from-remote-server --stop-never --verify-binlog-checksum

  then it will retrieve binary logs from whichever master it is pointed to, and store them locally on disk in the same format as they were written on the master. Here is an example with the extra arguments that would normally be used:

/usr/bin/mysqlbinlog --raw --read-from-remote-server \
 --stop-never --connection-server-id=1234 \
 --verify-binlog-checksum \
 --host=localhost --port=3306 mysql-bin.000024

This would retrieve the localhost binary logs (starting from mysql-bin.000024) reporting as server_id 1234, verify the checksum and then write each of them to disk.

Changes to the mysqlbinlog source code are relatively infrequent, except for when developing for a new major version, so you may be fooled into thinking that the specific version that you use is not so important—a little like the client version. This is something that is more likely to vary when you are taking remote backups.

Here is the result from the 5.7 branch of mysql-server to show the history of commits by year:

$ git blame --line-porcelain client/mysqlbinlog.cc | egrep "^(committer-time|committer-tz)" | cut -f2 -d' ' | while read ct; do read ctz; date --date "Jan 1, 1970 00:00:00 ${ctz} + ${ct} seconds" --utc +%Y; done | sort -n | uniq -c
   105 2000
    52 2001
    52 2002
   103 2003
   390 2004
   113 2005
    58 2006
   129 2007
   595 2008
    53 2009
   349 2010
   151 2011
   382 2012
   191 2013
   308 2014
   404 2015
    27 2016
    42 2017
    15 2018

Since the first GA release of 5.7 (October 2015), there haven’t been too many bugs and so if you aren’t using new features then you may think that it is OK to keep using the same version as before:

$ git log --regexp-ignore-case --grep bug --since="2015-10-19" --oneline client/mysqlbinlog.cc
1ffd7965a5e Bug#27558169 BACKPORT TO 5.7 BUG #26826272: REMOVE GCC 8 WARNINGS [noclose]
17c92835bb3 Bug #24674276 MYSQLBINLOG -R --HEXDUMP CRASHES FOR INTVAR,                   USER_VAR, OR RAND EVENTS
052dbd7b079 BUG#26878022 MYSQLBINLOG: ASSERTION `(OLD_MH->M_KEY == KEY) ||              (OLD_MH->M_KEY == 0)' FAILED
543129a577c BUG#26878022 MYSQLBINLOG: ASSERTION `(OLD_MH->M_KEY == KEY) || (OLD_MH->M_KEY == 0)' FAILED
ba1a99c5cd7 Bug#26825211 BACKPORT FIX FOR #25643811 TO 5.7
567bb732bc0 Bug#22932576 MYSQL5.6 DOES NOT BUILD ON SOLARIS12
efc42d99469 Bug#22932576 MYSQL5.6 DOES NOT BUILD ON SOLARIS12
6772eb52d66 Bug#21697461 MEMORY LEAK IN MYSQLBINLOG

However, this is not always the case and some issues are more obvious than others! To help show this, here are a couple of the issues that you might happen to notice.

Warning: option ‘stop-never-slave-server-id’: unsigned value <xxxxxxxx> adjusted to <yyyyy>

The server_id that is used by a server in a replication topology should always be unique within the topology. One of the easy ways to ensure this is to use a conversion of the external IPv4 address to an integer, such as INET_ATON , which provides you with an unsigned integer.

The introduction of


 (which deprecates


 ) changes the behaviour here (for the better). Prior to this you may experience warnings where your server_id was cast to the equivalent of an UNSIGNED SMALLINT. This didn’t seem to be a reported bug, just fixed as a by-product of the change.

ERROR: Could not find server version: Master reported unrecognized MySQL version ‘xxx’

When running mysqlbinlog, the version of MySQL is checked so that the event format is set correctly. Here is the code from MySQL 5.7:

switch (*version) {
 case '3':
   glob_description_event= new Format_description_log_event(1);
 case '4':
   glob_description_event= new Format_description_log_event(3);
 case '5':
     The server is soon going to send us its Format_description log
     event, unless it is a 5.0 server with 3.23 or 4.0 binlogs.
     So we first assume that this is 4.0 (which is enough to read the
     Format_desc event if one comes).
   glob_description_event= new Format_description_log_event(3);
   glob_description_event= NULL;
   error("Could not find server version: "
         "Master reported unrecognized MySQL version '%s'.", version);
   goto err;

This section of the code last changed in 2008, but of course there is another vendor that no longer uses a 5-prefixed-version number: MariaDB. With MariaDB, it is impossible to take a backup without using a MariaDB version of the program, as you are told that the version is unrecognised. The MariaDB source code contains a change to this section to resolve the issue when the version was bumped to 10:

83c02f32375b client/mysqlbinlog.cc (Michael Widenius    2012-05-31 22:39:11 +0300 1900) case 5:
83c02f32375b client/mysqlbinlog.cc (Michael Widenius    2012-05-31 22:39:11 +0300 1901) case 10:

Interestingly, MySQL 8.0 gets a little closer to not producing an error (although it still does), but finally sees off those rather old ancestral relatives:

 switch (*version) {
   case '5':
   case '8':
   case '9':
       The server is soon going to send us its Format_description log
     glob_description_event = new Format_description_log_event;
     glob_description_event = NULL;
         "Could not find server version: "
         "Master reported unrecognized MySQL version '%s'.",
     goto err;

These are somewhat trivial examples. In fact, you are more likely to suffer from more serious differences, perhaps ones that do not become immediately apparent, if you are not matching the mysqlbinlog version to the one provided by the version for the server producing the binary logs.

Sadly, it is not so easy to check the versions as the reported version was seemingly left unloved for quite a while (Ver 3.4), so you should check the binary package versions (e.g. using Percona-Server-client-57-5.7.23 with Percona-Server-server-57-5.7.23). Thankfully, the good news is that MySQL 8.0 fixes it!

So reduce the risk and match your package versions!


Announcement: Alpha Build of Percona Server 8.0

Percona Server for MySQL

Percona server for MySQLAlpha Build of Percona Server 8.0 released

An alpha version of Percona Server 8.0 is now available in the Percona experimental software repositories. This is a 64-bit release only. 

You may experiment with this alpha release by running it in a Docker container:

$ docker run -d -e MYSQL_ROOT_PASSWORD=password -p 3306:3306 perconalab/percona-server:8.0.12.alpha

When the container starts, connect to it as follows:

$ docker exec -ti $(docker ps | grep -F percona-server:8.0.12.alpha | awk '{print $1}') mysql -uroot -ppassword

Note that this release is not ready for use in any production environment.

Percona Server 8.0 alpha is available for the following platforms:

  • RHEL/Centos 6.x
  • RHEL/Centos 7.x
  • Ubuntu 16.04 Xenial
  • Ubuntu 18.04 Bionic
  • Debian 8 Jessie
  • Debian 9 Stretch

Note: The list of supported platforms may be different in the GA release.

Fixed Bugs:

  • PS-4814: TokuDB ‘fast’ replace into is incompatible with 8.0 row replication
  • PS-4834: The encrypted system tablespace has empty uuid

Other fixed bugs: PS-4788PS-4631PS-4736, PS-4818PS-4755

Unfinished Features

The following features are work in progress and are not yet in a working state:

  • Column compression with Data Dictionaries
  • Native Partitioning for TokuDB and for MyRocks
  • Encryption
    • Key Rotation
    • Scrubbing

Known Issues

  • PS-4788: Setting log_slow_verbosity and enabling the slow_query_log could lead to a server crash
  • PS-4803: ALTER TABLE … ADD INDEX … LOCK crash | handle_fatal_signal (sig=11) in dd_table_has_instant_cols
  • PS-4896: handle_fatal_signal (sig=11) in THD::thread_id likely due to enabling innodb_print_lock_wait_timeout_info
  • PS-4820: PS crashes with keyring_vault encryption
  • PS-4796: 8.0 DD and atomic DDL breaks DROP DATABASE for engines that store files in database directory
  • PS-4898: Crash during PAM authentication plugin installation.
  • PS-1782: Optimizer chooses wrong plan when joining 2 tables
  • PS-4850: Toku hot backup plugin dumps tons of info to stdout with no way to disable it
  • PS-4797: rpl.rpl_master_errors failing, likely due to binlog encryption
  • PS-4800: Recovery of prepared XA transactions seems broken in 8.0
  • PS-4853: Installing audit_log plugin causes server to crash
  • PS-4855: Replace http with https in http://bugs.percona.com in server crash messages
  • PS-4857: Improve error message handling for compressed columns
  • PS-4895: Improve error message when encrypted system tablespace was started without keyring plugin
  • PS-3944: Single variable to control logging in QRT
  • PS-4705: crash on snapshot size check in RocksDB
  • PS-4885: Using ALTER … ROW_FORMAT=TOKUDB_QUICKLZ leads to InnoDB: Assertion failure: ha_innodb.cc:12198:m_form->s->row_type == m_create_info->row_type

The post Announcement: Alpha Build of Percona Server 8.0 appeared first on Percona Database Performance Blog.


Replicating from MySQL 8.0 to MySQL 5.7

replicate from MySQL 8 to MySQL 5.7

In this blog post, we’ll discuss how to set a replication from MySQL 8.0 to MySQL 5.7. There are some situations that having this configuration might help. For example, in the case of a MySQL upgrade, it can be useful to have a master that is using a newer version of MySQL to an older version slave as a rollback plan. Another example is in the case of upgrading a master x master replication topology.

Officially, replication is only supported between consecutive major MySQL versions, and only from a lower version master to a higher version slave. Here is an example of a supported scenario:

5.7 master –> 8.0 slave

while the opposite is not supported:

8.0 master –> 5.7 slave

In this blog post, I’ll walk through how to overcome the initial problems to set a replication working in this scenario. I’ll also show some errors that can halt the replication if a new feature from MySQL 8 is used.

Here is the initial set up that will be used to build the topology:

slave > select @@version;
| @@version     |
| 5.7.17-log |
1 row in set (0.00 sec)
master > select @@version;
| @@version |
| 8.0.12    |
1 row in set (0.00 sec)

First, before executing the CHANGE MASTER command, you need to modify the collation on the master server. Otherwise the replication will run into this error:

slave > show slave status\G
                   Last_Errno: 22
                   Last_Error: Error 'Character set '#255' is not a compiled character set and is not specified in the '/opt/percona_server/5.7.17/share/charsets/Index.xml' file' on query. Default database: 'mysql8_1'. Query: 'create database mysql8_1'

This is because the default character_set and the collation has changed on MySQL 8. According to the documentation:

The default value of the character_set_server and character_set_database system variables has changed from latin1 to utf8mb4.

The default value of the collation_server and collation_database system variables has changed from latin1_swedish_ci to utf8mb4_0900_ai_ci.

Let’s change the collation and the character set to utf8 on MySQL 8 (it is possible to use any option that exists in both versions):

# master my.cnf

You need to restart MySQL 8 to apply the changes. Next, after the restart, you have to create a replication user using mysql_native_password.This is because MySQL 8 changed the default Authentication Plugin to caching_sha2_password which is not supported by MySQL 5.7. If you try to execute the CHANGE MASTER command with a user using caching_sha2_password plugin, you will receive the error message below:

Last_IO_Errno: 2059
Last_IO_Error: error connecting to master 'root@' - retry-time: 60 retries: 1

To create a user using mysql_native_password :

master> CREATE USER 'replica_user'@'%' IDENTIFIED WITH mysql_native_password BY 'repli$cat';
master> GRANT REPLICATION SLAVE ON *.* TO 'replica_user'@'%';

Finally, we can proceed as usual to build the replication:

master > show master status\G
*************************** 1. row ***************************
File: mysql-bin.000007
Position: 155
1 row in set (0.00 sec)
slave > CHANGE MASTER TO MASTER_HOST='', MASTER_USER='replica_user', MASTER_PASSWORD='repli$cat',MASTER_PORT=19025, MASTER_LOG_FILE='mysql-bin.000007', MASTER_LOG_POS=155; start slave;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
Query OK, 0 rows affected (0.00 sec)
# This procedure works with GTIDs too
slave > CHANGE MASTER TO MASTER_HOST='', MASTER_USER='replica_user', MASTER_PASSWORD='repli$cat',MASTER_PORT=19025,MASTER_AUTO_POSITION = 1 ; start slave;

Checking the replication status:

master > show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_User: replica_user
Master_Port: 19025
Connect_Retry: 60
Master_Log_File: mysql-bin.000007
Read_Master_Log_Pos: 155
Relay_Log_File: mysql-relay.000002
Relay_Log_Pos: 321
Relay_Master_Log_File: mysql-bin.000007
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Last_Errno: 0
Skip_Counter: 0
Exec_Master_Log_Pos: 155
Relay_Log_Space: 524
Until_Condition: None
Until_Log_Pos: 0
Master_SSL_Allowed: No
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_SQL_Errno: 0
Master_Server_Id: 100
Master_UUID: 00019025-1111-1111-1111-111111111111
Master_Info_File: /home/vinicius.grippa/sandboxes/rsandbox_5_7_17/master/data/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Auto_Position: 0
1 row in set (0.01 sec)

Executing a quick test to check if the replication is working:

master > create database vinnie;
Query OK, 1 row affected (0.06 sec)

slave > show databases like 'vinnie';
| Database (vinnie) |
| vinnie |
1 row in set (0.00 sec)


Any tentative attempts to use a new feature from MySQL 8 like roles, invisible indexes or caching_sha2_password will make the replication stop with an error:

master > alter user replica_user identified with caching_sha2_password by 'sekret';
Query OK, 0 rows affected (0.01 sec)

slave > show slave status\G
               Last_SQL_Errno: 1396
               Last_SQL_Error: Error 'Operation ALTER USER failed for 'replica_user'@'%'' on query. Default database: ''. Query: 'ALTER USER 'replica_user'@'%' IDENTIFIED WITH 'caching_sha2_password' AS '$A$005$H	MEDi\"gQ


Replicating from MySQL 8 to MySQL 5.7 is possible. In some scenarios (especially upgrades), this might be helpful, but it is not advisable to have a heterogeneous topology because it will be prone to errors and incompatibilities under some cases.

You might also like:


The post Replicating from MySQL 8.0 to MySQL 5.7 appeared first on Percona Database Performance Blog.


How to obtain the MySQL version from an FRM file

I recently helped a customer figure out why a minor version MySQL upgrade was indicating that some tables needed to be rebuilt. The mysql_upgrade program should be run for every upgrade, no matter how big or small the version difference is, but when only the minor version changes, I would normally not expect it to require tables to be rebuilt.

Turns out some of their tables were still marked with an older MySQL version, which could mean a few things… most likely that something went wrong with a previous upgrade, or that the tables were copied from a server with an older version.

In cases like this, did you know there is a fast, safe and simple way to check the version associated with a table? You can do this by reading the FRM file, following the format specification found here.

If you look at that page, you’ll see that the version is 4 bytes long and starts at offset 0x33. Since it is stored in little endian format, you can get the version just by reading the first two bytes.

This means you can use hexdump to read 2 bytes, starting at offset 0x33, and getting the decimal representation of them, to obtain the MySQL version, like so:

telecaster:test fernandoipar$ hexdump -s 0x33 -n 2 -v -d 55_test.frm
0000033 50532
telecaster:test fernandoipar$ hexdump -s 0x33 -n 2 -v -d 51_test.frm
0000033 50173

The first example corresponds to a table created on MySQL version 5.5.32, while the second one corresponds to 5.1.73.

Does that mean the 51_test table was created on 5.1.73? Not necessarily, as MySQL will update the version on the FRM whenever the table is rebuilt or altered.

The manual page says the details can change with the transition to the new text based format, but I was able to get the version using this command up to version MySQL 5.7.7.

Hope you found that useful!

The post How to obtain the MySQL version from an FRM file appeared first on MySQL Performance Blog.

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