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Displaying posts with tag: Replication (reset)
Replicating from a higher to lower MySQL version

As we know, replication is only supported officially between consecutive major MySQL versions, and only from a lower version master to a higher version slave.

This means for example, the following scenario is supported:
5.6 master –> 5.7 slave

while these two scenarios are not supported:
5.5 master –> 5.7 slave
5.7 master –> 5.6 slave

That being said, in some contexts (e.g a MySQL upgrade) it can be valuable to be able to replicate from a master that is using a newer version of MySQL to an older version slave.

This could be used as part of a rollback strategy, and/or be needed in the case of upgrading a master-master replication topology.

The idea of the article is to provide you …

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Tungsten Replicator and Clustering 5.2.0 Released

Continuent are pleased to announce the release of Tungsten Replicator and Tungsten Clustering 5.2.0

This release is one of our most exciting new releases for a while, as it contains some significant new features and lays the groundwork for some additional new functionality in the upcoming 5.3.0 and 6.0 releases due later this year.

In particular, this release includes the following new features:

  • New replicator filtering environment to make filtering quicker and easier to use, and more flexible
    • New filter configuration standard for new filters
    • New filter to make replication out of a cluster easier
    • New filters for filtering events and data
  • New applier for sending Apache Kafka messages directly from an incoming data stream
  • New applier for adding incoming records directly to Elasticsearch for indexing
  • New …
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Fun with Bugs #54 - On Some Bugs Fixed in MySQL 5.7.19

More than 3 months after 5.7.18 we' ve got MySQL 5.7.19 released recently. This is my quick review of the release notes with interesting fixed bug (reported in public) highlighted in the areas I am usually interested in.

Let's start with InnoDB. The following bug fixes attracted my attention:

  • Bug #85043 is still private. You know how much I hate those. At least we can see it was about the fact that "The server allocated memory unnecessarily for an operation that rebuilt the table." Let's hope this is no longer the case.
  • Bug …
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Group Replication – Extending Group Replication performance_schema tables

In MySQL 8.0.2, users will see the additional columns in the existing Group Replication Performance Schema tables which will provide extended information about Group Replication. Now user can view role and MySQL version of each member of the group, which earlier required a complex set of query.…

Multi-Threaded Slave Statistics

In this blog post, I’ll talk about multi-threaded slave statistics printed in MySQL error log file.

MySQL version 5.6 and later allows you to execute replicated events using parallel threads. This feature is called Multi-Threaded Slave (MTS), and to enable it you need to modify the

slave_parallel_workers

 variable to a value greater than 1.

Recently, a few customers asked about the meaning of some new statistics printed in their error log files when they enable MTS. These error messages look similar to the example stated below:

[Note] Multi-threaded slave statistics for channel '': seconds elapsed = 123; events assigned = 57345; worker queues filled over overrun level = 0; waited due a Worker queue full = 0; waited due the total size = 0; waited at clock conflicts = 0 waited …
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Replication Features in MySQL 8.0.2

MySQL 8 is shaping up quite nicely. And we are having a blast in the MySQL replication team while this is happening. We are continuously improving all-things-replication by introducing new and interesting features. In addition, we have been listening to our community and addressing their feedback.…

Upcoming Webinar, 19th July, What is New in Tungsten Replicator 5.2 and Tungsten Clustering 5.2?

Continuent Tungsten 5.2 is just around the corner. This is one of our most exciting Tungsten product releases for some time!

In this webinar we’re going to have a look at a host of new features in the new release, including
Three new Replication Applier Targets (Kafka, Cassandra and Elasticsearch)
New improvements to our core command-line tools trepctl and thl
New foundations for our filtering services, and
Improvements to the compatibility between replication and clustering

This webinar is going be a packed session and we’ll show all the exciting stuff with more in-depth follow-up sessions in the coming weeks.

 

You’ll also learn about some more exciting changes coming in the upcoming Tungsten releases (5.2.1 and 5.3), and our major Tungsten 6.0 release due out by the end of the year.

So come and join us to get the low down on everything related to …

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SET PASSWORD will lock you out of your slave in a mixed 5.6/5.7 MySQL topology

Long time no post.... :-)
Here's something interesting.

Last week I decided to give MySQL 5.7 a try (yes, I am kinda conservative DBA...) and the very same day that I installed my first 5.7 replica I noticed that, after changing my own password on the 5.6 master, I could no longer connect to the 5.7 slave.

Very annoying, to say the least! So I went and dug out the root password (which we do not normally use) and when I connected to the slave I was surprised to see that my password's hash on the 5.7 slave was different than the hash on the 5.6 master. No wonder I couldn't connect....

A bit of research on the MySQL documentation and I understood that 5.7 introduced few changes around the way you work with users' passwords.  SET PASSWORD is now deprecated in favour of ALTER USER: see MySQL 5.7 Reference Manual …

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What's so complicated about a master failover?

The more work on orchestrator, the more user input and the more production experience, the more insights I get into MySQL master recoveries. I'd like to share the complexities in correctly running general-purpose master failovers; from picking up the right candidates to finalizing the promotion.

The TL;DR is: we're often unaware of just how things can turn at the time of failover, and the impact of every single decision we make. Different environments have different requirements, and different users wish to have different policies. Understanding the scenarios can help you make the right choice.

The scenarios and considerations below are ones I picked while browsing through the orchestrator code and through Issues and questions. There are more. There are always more scenarios.

I discuss "normal replication" scenarios below; some of these will …

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The MySQL High Availability Landscape in 2017 (The Elders)

In this blog, we’ll look at different MySQL high availability options.

The dynamic MySQL ecosystem is rapidly evolving many technologies built around MySQL. This is especially true for the technologies involved with the high availability (HA) aspects of MySQL. When I joined Percona back in 2009, some of these HA technologies were very popular – but have since been almost forgotten. During the same interval, new technologies have emerged. In order to give some perspective to the reader, and hopefully help to make better choices, I’ll review the MySQL HA landscape as it is in 2017. This review will be in three parts. The first part (this post) will cover the technologies that have been around for a long time: the elders. The second part will focus on the technologies that are very popular today: the adults. Finally, the last part will try to extrapolate which technologies could become popular in the upcoming years: the …

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