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Displaying posts with tag: Replication (reset)
Webinar Wednesday January 18, 2017: Lessons from Database Failures

Join Percona’s Chief Evangelist Colin Charles on Wednesday, January 18, 2017, at 7:00 am (PST) / 10:00 am (EST) (UTC-8) as he presents “Lessons from Database Failures.”

MySQL failures at scale can teach a great deal. MySQL failures can lead to a discussion about such topics as high availability (HA), geographical redundancy and automatic failover. In this webinar, Colin will present case study material (how automatic failover caused Github to go offline, why Facebook uses assisted failover rather than fully automated failover, and other scenarios) to look at how the MySQL world is making things better. One way, for example, is using …

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MySQL group replication: installation with Docker


MySQL Group Replication was released as GA with MySQL 5.7.17. It is essentially a plugin that, when enabled, allows users to set replication with this new way.

There has been some confusion about the stability and usability of this release. Until recently, MySQL Group Replication (MGR) was only available in the Labs, which traditionally denotes a preview or an use-at-your-own-risk feature. Several months ago we saw the release of Group Replication as a Docker image, which allowed users to deploy a peer-to-peer cluster (every node is a master.) However, about one month after such release, word came from Oracle discouraging this setup, and inviting users to use Group Replicator in …

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Solving MySQL Replication Lag with LOGICAL_CLOCK and Calibrated Delay

Last week VividCortex's Preetam Jinka published a post on his personal blog examining how our engineering team had overcome a problem with MySQL replication by using a new parallelization policy introduced in MySQL 5.7: LOGICAL_CLOCK.

Image Credit

The solution we developed—which achieves faster replication via group commit and a carefully calibrated delay—can offer huge replication improvements, but its implementation isn't immediately obvious or intuitive. We thought it worthwhile to provide a fuller description of how we arrived at the solution Preetam outlined.

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Oracle MySQL and the funny replication breakage of Friday, January 13

In my previous post, I talked about a funny replication breakage that I experienced with MariaDB.  So what about different versions of MySQL... > SELECT version(); +------------+ | version() | +------------+ | 5.6.35-log | +------------+ 1 row in set (0.00 sec) > SELECT * FROM test_jfg; +----+--------+-------------+ | id | status

Funny replication breakage of Friday, January 13

A funny replication breakage kept me at the office longer than expected today (Friday 13 is not kind with me).

So question of the day: can you guess what the below UPDATE statement does (or what is wrong with it)?


Galera Cluster: adding a primary key to a MySQL table which lacks it... without downtime

OK, let me start with saying that a table without a primary key shouldn't be something that a DBA should ever stumble into.  Sure, InnoDB will secretly add one for us without telling - but that's not something we can use at application or administration level, it's just to make the engine happy.

So let's suppose you find some tables that lack a primary key, of course you need to do something about it, right?  Now, put Galera Cluster in the mix - Galera does not support tables without a primary key and will, secretly again, make that table inconsistent at cluster level.

You need to fix the damn table(s)!! And this is where the fun begins...  as you can't afford downtime for the operation so you need to resort to an online schema change of some type.

Galera cluster 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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MySQL 8.0.0 first impressions: been running for 60 days

While headlines likes this are really silly I thought it might be worth sharing some experience with 8.0.0 on a few servers I use. I tend to test new versions of MySQL first as a slave. That is easy as it requires little work: make a copy of a working 5.7 slave, upgrade the server … Continue reading MySQL 8.0.0 first impressions: been running for 60 days

Discussing online schema migrations with Oracle's MySQL engineering managers

Last week I had the pleasant opportunity of introducing and discussing the operation of online schema migrations to MySQL's engineering managers, as part of their annual meeting, in London.

Together with Simon J. Mudd of, we discussed our perception of what it takes to run online schema migrations on a live, busy system.

While the Oracle/MySQL engineers develop new features or optimize behavior in the MySQL, we of the industry have the operational expertise and understanding of the flow of working with MySQL. In all topics, and in schema migration in particular, there is a gap between what's perceived to be the use case and what the use case actually is. It is the community's task to provide feedback back to Oracle so as to align development to match operations need where possible.

Our meeting included the following:

Need for schema migrations

We presented, based on our …

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MySQL Support Engineer's Chronicles, Issue #3

The original idea of this series was to publish one post per week, but it seems every other week I have some special topic that well deserves a dedicated post. Last week I had no time to complete my writing because of long (and, I hope, useful) Howto post on replacing corrupted partition using non-corrupted one from other server in replication setup. But I had links and notes collected in a draft that I am going to complete now.

First of all, during the previous week I had time to submit two more talks for the  …

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