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Displaying posts with tag: mysqlbinlog (reset)
On MySQL Replication Bugs

While writing about problematic Oracle MySQL features previously I concentrated mostly on InnoDB problems that I have to fight with really often and deliberately skipped replication from even the preliminary list of features to study in details for that blog post. First of all, I mostly work with MariaDB users now, and implementation of many replication features in MariaDB is notably different already (and has its own list of known problems). But this happened also because (asynchronous) replication plays a key role in most MySQL environments and deserves a detailed study in a separate post.

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Fun with Bugs #56 - On Some Public Bugs Fixed in MySQL 5.7.20

While MySQL 8.0.x hardly has much impact on my regular work, recent MySQL 5.7.20 release is something to check carefully. MySQL 5.7 is widely used in production, as a base for Percona Server 5.7, some features may be merged into MariaDB 10.x etc. So, here is my review of some community reported bugs that were fixed in recently released MySQL 5.7.20, based on the release notes.

Usually I start with InnoDB bug fixes, but in 5.7.20 several related fixes were made only to bugs reported internally. So, this time I have to start with partitioning:

  • Bug #86255 - First one to write about, and the bug report is …
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Fun with Bugs #46 - On Some Bugs I've Reported During the Year of 2016

It's time to summarize the year of 2016. As a kind of a weird summary, in this post I'd like to share a list of MySQL bug reports I've created in 2016 that are still remaining "Verified" today:

  • Bug #79831 - "Unexpected error message on crash-safe slave with max_relay_log_size set". According to Umesh this is not repeatable with 5.7. The fact that I've reported the bug on January 4 probably means I was working at that time. I should not repeat this mistake again next year.
  • Bug #80067 - "Index on BIT column is NOT used when column name only is used in WHERE clause". People say the same problem happens with INT and, what may be even less expected, BOOLEAN columns.
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MariaDB 10.0.17 Overview and Highlights

MariaDB 10.0.17 was recently released, and is available for download here:

https://downloads.mariadb.org/mariadb/10.0.17/

This is the eighth GA release of MariaDB 10.0, and 18th overall release of MariaDB 10.0.

For the most part, there are not a whole lot of new changes to report for this release, but there is a new version of the Audit Plugin and many other engines have been updated as well.

Here are the main items of note:

  1. The new version of the Audit Plugin is 1.2 is included with the following new features:
    • In the audit log passwords are now masked, i.e. the password characters are replaced with asterisks.
    • It’s now possible to filter logging to include only DDL (CREATE, ALTER, etc.) or DML (INSERT, UPDATE, etc.) statements.
    • For more information …
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Identifying useful info from MySQL row-based binary logs

As a MySQL DBA/consultant, it is part of my job to decode the MySQL binary logs – and there are a number of reasons for doing that. In this post, I’ll explain how you can get the important information about your write workload using MySQL row-based binary logs and a simple awk script.

First, it is important to understand that row-based binary logs contain the actual changes done by a query. For example, if I run a delete query against a table, the binary log will contain the rows that were deleted. MySQL provides the mysqlbinlog utility to decode the events stored in MySQL binary logs. You can read more about mysqlbinlog in detail in the reference manual here.

The following example illustrates how mysqlbinlog displays row events that specify data modifications. These correspond to events with the WRITE_ROWS_EVENT, UPDATE_ROWS_EVENT, …

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Recover Lost MySQL data with mysqlbinlog point-in-time-recovery example

Backup ... backup... Backup... but of course.. you also need to monitor and test those backups often otherwise they could be worthless.  Having your MySQL binlogs enabled can certainly help you in times of an emergency as well.  The MySQL binlogs are often referenced in regards to MySQL replication, for a good reason, they store all of the queries or events that alter data (row-based is a little different but this an example). The binlogs have a minimal impact on server performance when considering the recovery options they provide.


[anothermysqldba]> show variables like 'log_bin%';
+---------------------------------+--------------------------------------------+
| …

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MySQL 5.7 Replication: mysqlbinlog tool idempotent mode while applying row events


IntroductionMySQL replication slave features  a powerful capability of ignoring conflicts like duplicate key error, key not found errors etc. while applying row events.  This is exceptionally useful while doing row based replication(RBR) from the master when the slave already contains some data which may conflict with the data coming from the master. In MySQL 5.7 we extend this capability while applying row events from mysql-binlog files using mysqlbinlog tool.  This enhancement will prevent such errors from aborting mysql client in case of conflicts like the ones mentioned above.

RationalePrior to MySQL 5.7 we have been using the mysqlbinlog tool as follows.

shell$> mysqlbinlog master.000001|mysql -uroot -hexample.com -ps3cret  

This allows us to pipe the output of mysqlbinlog to mysql, and works as long as the row events from the mysqlbinlog do not conflict with …

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Binlogs 101

The mysqlbinlog are not new. We often reference it and all of the valuable information that it provides. I thought it might be useful to show some simple examples on how to get some of that information, for those unfamiliar with the mysqlbinlog tool.

For this example, I used the MySQL benchmark tools to populate data.

You can review binary log events a couple if different ways.
You can use the command line :

      mysqlbinlog mysql56rc-bin.000010
or within MySQL via a simple query.
      SHOW BINLOG EVENTS IN 'mysql56rc-bin.000010' ;

These will both dump out all of the data, and this demo currently has 2284725 rows of data, to much to review …

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Binary Log Replayer

When using the replication slave stream, or mysql command line client and mysqlbinlog output from a binary/relay log, all statements are executed in a single thread as quickly as possible.

I am seeking a tool to simulate the replay of the binary/relay log for a benchmark at a pace that is more representative to original statements. For a simple example, if the Binary Log has 3 transactions in the first second, 2 transactions in the second second, and 5 transactions in the third second, I am wanting to simulate the replay to take roughly 3 seconds, not as fast as possible (which would be sub-second). The tool should try to wait the remainder of a second before processing SQL statements in the incoming stream.

Does anybody know of a tool that currently provides this type of functionality? Any input appreciated before I create my own.

My contribution to MySQL 5.6

[caption id="attachment_209" align="alignright" width="240" caption="Photo by Stéfan under a CC by NC SA 2.0 license"][/caption]

If you have been reading Planet MySQL over April you will have seen many blog posts on the new features in the MySQL 5.6 (currently a development release).  I developed several patches that are in 5.6 including the 'Slave_last_heartbeat' status variable to show the time of the last replication heartbeat received.  One of the cool new features I developed which I am most proud of is the option to remotely backup …

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