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Search Results for: multi column index

Quickly finding unused indexes (and estimating their size)

I had a customer recently who needed to reduce their database size on disk quickly without a lot of messy schema redesign and application recoding.  They didn’t want to drop any actual data, and their …

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Three Ways that Fractal Tree Indexes Improve SSD for MySQL

Since Fractal Tree indexes turn random writes into sequential writes, it’s easy to see why they offer a big advantage for maintaining indexes on rotating disks. It turns out that that Fractal Tree indexing also …

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Find and remove duplicate indexes

Having duplicate keys in our schemas can hurt the performance of our database: They make the optimizer phase slower because MySQL needs to examine more query plans. The storage engine needs to maintain, calculate and …

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Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

This is the second 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 aimed at the optimizer …

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Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact

I have been working with Peter in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at and benchmarking optimizer enhancements one by one. So …

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Announcing TokuDB v5.2: Improved Multi-Client Scaling and Faster Queries

TokuDB® v5.2, the latest version of Tokutek’s flagship storage engine for MySQL and MariaDB, is now available. This version offers performance enhancements over previous releases, especially for multi-client scale up and point queries, and extends …

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3 ways MySQL uses indexes

I often see people confuse different ways MySQL can use indexing, getting wrong ideas on what query performance they should expect. There are 3 main ways how MySQL can use the indexes for query execution, …

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Clustering indexes vs. Covering indexes

Yesterday, I (Zardosht) posted an entry introducing clustering indexes. Here, I elaborate on three differences between a clustering index and a covering index: Clustering indexes can create indexes that would otherwise bounce up against the …

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How to find wrong indexing with glance view

Quite common beginners mistake is not to understand how indexing works and so index all columns used in the queries…. separately. So you end up with table which has say 20 indexes but all single …

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Should you name indexes while doing ALTER TABLE ?

MySQL Server does not require you to specify name of the index if you’re running ALTER TABLE statement – it is optional. Though what might be good practical reasons to specify the key name or …

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