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Search Results for: table join on index

MySQL Indexing Best Practices: Webinar Questions Followup

I had a lot of questions on my MySQL Indexing: Best Practices Webinar (both recording and slides are available now) We had lots of questions. I did not have time to answer some and others …

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Innodb Table Locks

Innodb uses row level locks right ? So if you see locked tables reported in SHOW ENGINE INNODB STATUS you might be confused and rightfully so as Innodb table locking is a bit more complicated …

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On Character Sets and Disappearing Tables

The MySQL manual tells us that regardless of whether or not we use “SET FOREIGN_KEY_CHECKS=0” before making schema changes, InnoDB will not allow a column referenced by a foreign key constraint to be modified in …

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A case for MariaDB’s Hash Joins

MariaDB 5.3/5.5 has introduced a new join type “Hash Joins” which is an implementation of a Classic Block-based Hash Join Algorithm. In this post we will see what the Hash Join is, how it works …

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Join Optimizations in MySQL 5.6 and MariaDB 5.5

This is the third blog post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is targeted at the join …

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How to recover deleted rows from an InnoDB Tablespace

In my previous post I explained how it could be possible to recover, on some specific cases, a single table from a full backup in order to save time and make the recovery process more …

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When Does InnoDB Update Table Statistics? (And When It Can Bite)

An InnoDB table statistics is used for JOIN optimizations and helping the MySQL optimizer choose the appropriate index for a query. If a table’s statistics or index cardinality becomes outdated, you might see queries which …

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Are You Forcing MySQL to Do Twice as Many JOINs as Necessary?

by:

. Baron Schwartz This guest post is from our friends at Percona. They’re hosting Percona Live London from October 24-25, 2011. Percona Live is a two day summit with 100% technical sessions led by some …

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How well does your table fits in innodb buffer pool ?

Understanding how well your tables and indexes fit to buffer pool are often very helpful to understand why some queries are IO bound and others not – it may be because the tables and indexes …

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Advanced index analysis with mk-index-usage

The new release of Maatkit has a useful feature in mk-index-usage to help you determine how indexes are used in more flexible ways. The default report just prints out ALTER statements for removing unused indexes, …

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