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Showing entries 1 to 10 of 34 10 Older Entries

Displaying posts with tag: Stéphane Combaudon (reset)

Test your knowledge: Percona XtraDB Cluster (PXC) quiz
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I often talk with people who are very interested in the features of Percona XtraDB Cluster (PXC) such as synchronous and parallel replication, multi-node writing and high availability. However some get confused when operating a real PXC cluster because they do not fully realize the implications of these features. So here is a fun way to test your PXC knowledge: try to solve these 12 questions related to PXC! (you will find the answers at the end of the post.)

Workload

1. With Galera 3.x, support for MyISAM is experimental. When can we expect to have full MyISAM support?
a. This will never happen as …

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Indexing 101: Optimizing MySQL queries on a single table
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I have recently seen several cases when performance for MySQL queries on a single table was terrible. The reason was simple: the wrong indexes were added and so the execution plan was poor. Here are guidelines to help you optimize various kinds of single-table queries.

Disclaimer: I will be presenting general guidelines and I do not intend to cover all scenarios. I am pretty confident that you can find examples where what I am writing does not work, but I am also confident that it will help you most of the time. Also I will not discuss features you can find in MySQL 5.6+ like Index Condition Pushdown to keep things …

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MySQL shell prompt vs MongoDB shell prompt
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Recently Todd Farmer shared an interesting story about the mysql command line prompt in MySQL 5.7: how it was changed to provide more context and why the change was finally reverted. This made me think that after using the command line client for MongoDB for awhile, I would love seeing a much more modern mysql shell prompt. Here are a few examples of what a modern command line client can do.

Add dynamic information to the prompt

If you use replication with MongoDB, you have probably noticed a nice feature of the prompt: it is replication …

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Choosing a good sharding key in MongoDB (and MySQL)
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MongoDB 3.0 was recently released. Instead of focusing on what’s new – that is so easy to find, let’s rather talk about something that has not changed a lot since the early MongoDB days. This topic is sharding and most specifically: how to choose a good sharding key. Note that most of the discussion will also apply to MySQL, so if you are more interested in sharding than in MongoDB, it could still be worth reading.

When do you want to shard?

In general sharding is recommended with MongoDB as soon as any of these conditions is met:

  • #1: A single server can no longer handle the write workload.
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Q&A: Multi-threaded Replication in MySQL 5.6 and MySQL 5.7
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My webinar “Multi-threaded Replication in MySQL 5.6 and 5.7″ on February 25 generated several excellent questions following the presentation (available here for playback along with the slides). I didn’t have time to answer many of the questions during the session and so in this post I answer all of them. Thanks to everyone who attended!

Q: What do you expect from MTS with logical clock? Do you think performance would be good as with per database?
A: MTS with 5.6 is not usable …

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Emulating MySQL roles with the Percona PAM plugin and proxy users
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From time to time people wonder how to implement roles in MySQL. This can be useful for companies having to deal with many user accounts or for companies with tight security requirements (PCI or HIPAA for instance). Roles do not exist in regular MySQL but here is an example on how to emulate them using Percona Server, the PAM plugin and proxy users.

The goal

Say we have 2 databases: db1 and db2, and we want to be able to create 3 roles:

  • db1_dev: can read and write on db1 only.
  • db2_dev: can read and write on db2 only. …
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More on MySQL 5.6 multi-threaded replication and GTIDs (and Feb. 25 webinar)
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In a previous post, titled “Multi-threaded replication with MySQL 5.6: Use GTIDs,” I explained that using GTID replication is almost a requirement when using MySQL 5.6 MTS. Let’s see now how to perform the day-to-day operations when MTS and GTIDs are both enabled. (I’ll also be presenting a related webinar next week titled “Multi-threaded Replication in MySQL 5.6 and …

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Percona XtraDB Cluster 5.6: a tale of 2 GTIDs
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Say you have a cluster with 3 nodes using Percona XtraDB Cluster (PXC) 5.6 and one asynchronous replica connected to node1. If asynchronous replication is using GTIDs, moving the replica so that it is connected to node2 is trivial, right? Actually replication can easily break for reasons that may not be obvious at first sight.

Summary

Let’s assume we have the following setup with 3 PXC nodes and one asynchronous replica:

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Online GTID rollout now available in Percona Server 5.6
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Global Transaction IDs (GTIDs) are one of my favorite features of MySQL 5.6. The main limitation is that you must stop all the servers at the same time to allow GTID-replication. Not everyone can afford to take a downtime so this requirement has been a showstopper for many people. Starting with Percona Server 5.6.22-72.0 enabling GTID replication can be done without almost no downtime. Let’s see how to do it.

Implementation of the Facebook patch

Finding a solution to migrate to …

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Multi-threaded replication with MySQL 5.6: Use GTIDs!
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MySQL 5.6 allows you to execute replicated events in parallel as long as data is split across several databases. This feature is named “Multi-Threaded Slave” (MTS) and it is easy to enable by setting slave_parallel_workers to a > 1 value. However if you decide to use MTS without GTIDs, you may run into annoying issues. Let’s look at two of them.

Skipping replication errors

When replication stops with an error, a frequent approach is to “ignore now and fix later.” This means you will run SET GLOBAL sql_slave_skip_counter=1 to be able to restart replication as quickly as possible and …

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Showing entries 1 to 10 of 34 10 Older Entries

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