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Displaying posts with tag: buffer pool (reset)
Exposing Innodb Internals via System Variables: Part 1, Memory

Introduction

A couple of months ago I decided to give myself a refresher on the mechanics of InnoDB. Having a high level understanding of what’s going on under the hood can help provide the context needed in order to resolve issues you may encounter as well as assist you in ensuring that your MySQL instance is running efficiently. Everyone can stand to go back to basics every now and then, as it can help you pick up concepts that you may have missed the last time you researched the topic.

This time around I decided to give myself a refresher by re-reading the MySQL 5.6 reference manual, chapter 14, which covers the InnoDB engine. Despite having a wealth of documented knowledge and insights, I found that a lot of the points in the documentations were unclear, leading me to do more research and experimentation in order to get a bit of clarity on some of the specifics that I felt were missing. In order to help make the information …

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How well does your table fit in the InnoDB buffer pool in MySQL 5.6+?

Some time ago, Peter Zaitsev posted a blog titled “How well does your table fits in innodb buffer pool?” He used some special INFORMATION_SCHEMA tables developed for Percona Server 5.1 to report how much of each InnoDB table and index resides in your buffer pool.

As Peter pointed out, you can use this view into the buffer pool to watch a buffer pool warm up with pages as you run queries. You can also use it for capacity planning. If you expect some tables need to be fully loaded in the buffer pool to be used efficiently, but the buffer pool isn’t large enough to hold them, then it’s time to increase the size of the buffer pool.

The problem, however, was that system tables change from version to version. Specifically, the INNODB_BUFFER_POOL_PAGES_INDEX table no longer exists in Percona Server 5.6, and the …

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Migrating between MySQL schemas with Percona Xtrabackup

Recently, I was working with a client that asked about using Percona Xtrabackup to take a snapshot of a particular MySQL schema and then reload it with a different schema name on the same server.  It caught me off guard because I’d never really thought about it – typically, I’ve used Xtrabackup simply to clone a server (for replication or migration) or migrate an existing schema to a new server.  However, given the import/export functionality of Xtrabackup combined with Percona Server (Exporting and Importing Tables), it did seem …

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When EXPLAIN estimates can go wrong!

This is the title of my first blog post on MySQL Performance Blog. It deals with a customer case where the customer was facing a peculiar problem where the rows column in the EXPLAIN output of the query was totally off. The actual number of rows was 18 times more than the number of rows reported by MySQL in the output of EXPLAIN. Now this can be a real pain as MySQL uses “the number of rows” estimation to pick and choose indexes and it could really be picking up a wrong index simply because of the wrong estimate. You...

The post When EXPLAIN estimates can go wrong! appeared first on ovais.tariq.

Shortened warm-up times with a preloaded InnoDB buffer pool

Are you running an InnoDB installation with a many-gigabytes buffer pool(s)? Does it take too long before it goes back to speed after a restart? If yes, then the following will be interesting to you.

In the latest MySQL 5.6 Labs release we have implemented an InnoDB buffer pool(s) dump and load to solve this problem.

The contents of the InnoDB buffer pool(s) can be saved on disk before MySQL is shut down and then read in after a restart so that the warm up time is drastically shortened – the buffer pool(s) go to the state they were before the server restart! The time needed for that is roughly the time needed to read data from disk that is about the size of the buffer pool(s).

Lets dive straight into the commands to perform various dump/load operations:

The buffer pool(s) dump can be done at any time when MySQL is running by doing:

  mysql> SET innodb_buffer_pool_dump_now=ON;

This …

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Why do I recommend switching over from MyISAM to Innodb!

Although MyISAM has been the default storage engine for MySQL but its soon going to change with the release of MySQL server 5.5. Not only that, more and more people are shifting over to the Innodb storage engine and the reasons for that is the tremendous benefits, not only in terms of performance, concurrency, ACID-transactions, foreign key constraints, but also because of the way it helps out the DBA with hot-backups support, automatic crash recovery and avoiding data inconsistencies which can prove to be a pain with MyISAM. In this article I try to hammer out the reasons why you should move on to using Innodb instead of MyISAM.

Showing entries 1 to 6