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Displaying posts with tag: Replication (reset)
Rescuing a crashed pt-online-schema-change with pt-archiver

This article discusses how to salvage a crashed pt-online-schema-change by leveraging pt-archiver and executing queries to ensure that the data gets accurately migrated. I will show you how to continue the data copy process, and how to safely close out the pt-online-schema-change via manual operations such as RENAME TABLE and DROP TRIGGER commands. The normal process to recover from a crashed pt-online-schema-change is to drop the triggers on your original table and drop the new table created by the script. Then you would restart pt-online-schema-change. In this case, this wasn’t possible.

A customer recently needed to add a primary key column to a very busy table (with around 200 million rows). The table only had a …

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How to setup MySQL replication on CentOS

In this tutorial we will show you how to setup basic MySQL replication on two CentOS 7 servers, but the same steps should work on all RPM based systems. We will use two test CentOS 7 virtual servers for this tutorial with the following IP addresses: MASTER: 123.456.789.1 SLAVE: 123.456.789.2 Master Server: Login to the master server as user root ssh root@IP_Address and install MySQL server if it is not already installed yum install mysql-server mysql Start the MySQL server and enable it to start at boot time systemctl start mysql systemctl enable mysql Next, open the MySQL configuration file […]

Fun with Bugs #43 - Bugs Fixed in MySQL 5.7.13

For some reason I do not see numerous public announcements about recent MySQL 5.7.13 release, even though it happened a couple of days ago formally. Maybe that's because we do not have any really "big" new features in this release (new ->> operator for introduced though for those who, unlike me, care about JSON). Still there are many fixes for bugs previously reported by Community (or Oracle engineers, but still in public bugs database), and I'd like to discuss some of them.

Let me start with the bug that was NOT fixed though, Bug #81093, "mysqld_multi not included in mysql-community-server package", reported by Georgi Iovchev and …

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The differences between IDEMPOTENT and AUTO-REPAIR mode

I posted recently Lossless RBR for MySQL 8.0 about a concern I have about moving to minimal RBR in MySQL 8.0.  This seems to be the direction that Oracle is considering, but I am not sure it is a good idea as a default setting. I talked about a hypothetical new replication mode lossless RBR and also about … Continue reading The differences between IDEMPOTENT and AUTO-REPAIR mode

pt-online-schema-change (if misused) can’t save the day

In this blog post we’ll discuss pt-online-schema-change, and how to correctly use it.

Always use pt-osc?

Altering large tables can be still a problematic DBA task, even now after we’ve improved Online DDL features in MySQL 5.6 and 5.7. Some ALTER types are still not online, or sometimes just too expensive to execute on busy production master.

So in some cases, we may want to apply an


 first on slaves, taking them out of traffic pool one by one and bringing them back after the


 is done. In the end, we can promote one of the already altered slaves to be new master, so that the downtime/maintenance time is greatly minimized. The ex-master can be altered later, without affecting production. Of course, this method works best when the schema change is …

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Lossless RBR for MySQL 8.0?

Lossless RBR TL/DR: There’s been talk of moving the next release of MySQL to minimal RBR: I’d like to suggest an alternative: lossless RBR For MySQL 5.8 there was talk / suggestions about moving to minimal RBR as the default configuration (  I’m not comfortable with this because it means that by default you do not have … Continue reading Lossless RBR for MySQL 8.0?

Fun with Bugs #42 - Bugs Fixed in MySQL 5.7.12

MySQL 5.7.12 was released more than 2 weeks ago. New features introduced there in a form of "rapid plugins" are widely discussed, but I am more interested in bugs reported by MySQL Community users that are fixed there. Unfortunately I do not see MySQL Community Release Notes by Morgan (like this) for quite a some time, so I have to continue describing key bug fixes and name people who reported and verified bugs in my "Fun with Bugs" series.

As usual, let's start with InnoDB bugs fixed:

  • Bug #80070 - "allocated_size and file_size differ if create general tablespace outside datadir". It was reported by my former colleague from Percona …
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Video on MySQL master slave Replication

A video session on "Intro to MySQL master slave Replication". Hope you enjoy it :)

How We Made MySQL Great Again, or Upgrading MySQL with Orchestrator

In this blog post, we’ll discuss upgrading MySQL with Orchestrator.

I recently had a client, Life360, that wanted to upgrade from Percona Server 5.5 to Percona Server 5.6, and implement GTID in their high transaction environment. They had co-masters and multiple read slaves.

Orchestrator made this job much easier for us. My colleague, Tibi, recently posted about Orchestrator here and here.

Daniel from Life360 saw Orchestrator and was very interested. So here is how he setup Orchestrator in his own words:

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Query Rewrite Plugin and Binlog for Replication

Starting with MySQL 5.7 we introduced the Query Rewrite Plugin. That tool is really useful for changing queries. Of course the best location to modify the query is the source code of the application, but this is not always possible. Either the application is not under your control or queries are generated from a framework like Hibernate and sometimes it is hard to change the query generation.
If you are interested in details about the Query Rewrite Plugin, I recommend this blogpost from the MySQL Engineering:
Recently I was asked how this works in replication environments. Which query goes into the binlog?

If you are using the Rewriter plugin that comes with MySQL 5.7, the answer is easy: This plugin only supports rewriting SELECT queries. SELECT queries don't get into the binlog …

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