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Search Results for: index order

A Second Rule of Thumb for Choosing Column Order in Indexes

A couple of weeks ago, Baron Schwartz wrote an interesting post describing a rule of thumb he sometimes uses to choose the order of columns in an index. In a nutshell, he recommends putting highly …

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A rule of thumb for choosing column order in indexes

I wanted to share a little rule of thumb I sometimes use to decide which columns should come first in an index. This is not specific to MySQL, it’s generally applicable to any database server …

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Covering Indexes: Orders-of-Magnitude Improvements

The talk I gave at the Percona Performance Conference at the MySQL Users Conference in April 2009 can be found here. This talk provides some examples where covering indexes help, and then describes a performance …

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Using index for ORDER BY vs restricting number of rows.

One interesting problem with MySQL Optimizer I frequently run into is making poor decision when it comes to choosing between using index for ORDER BY or using index for restriction. Consider we’re running web site …

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Find unused indexes on MongoDB and TokuMX

Finding and removing unused indexes is a pretty common technique to improve overall performance of relational databases. Less indexes means faster insert and updates but also less disk space used. The usual way to do …

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MySQL indexing 101: a challenging single-table query

We discussed in an earlier post how to design indexes for many types of queries using a single table. Here is a real-world example of the challenges you will face when trying to optimize queries: …

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Indexing 101: Optimizing MySQL queries on a single table

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 …

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InnoDB locks and deadlocks with or without index for different isolation level

Recently, I was working on one of the issue related to locks and deadlocks with InnoDB tables and I found very interesting details about how InnoDB locks and deadlocks works with or without index for different Isolation levels. …

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‘Indexing’ JSON documents for efficient MySQL queries over JSON data

MySQL meets NoSQL with JSON UDF I recently got back from FOSDEM, in Brussels, Belgium. While I was there I got to see a great talk by Sveta Smirnova, about her MySQL 5.7 Labs release …

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Importing big tables with large indexes with Myloader MySQL tool

Mydumper is known as the faster (much faster) mysqldump alternative. So, if you take a logical backup you will choose Mydumper instead of mysqldump. But what about the restore? Well, who needs to restore a …

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