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Search Results for: why force index

Why Percona Acquired Tokutek: by Peter Zaitsev

It is my pleasure to announce that Percona has acquired Tokutek and will take over development and support for TokuDB® and TokuMX™ as well as the revolutionary Fractal Tree® indexing technology that enables those products …


Why TokuMX Changed MongoDB’s Oplog Format for Operations

Over several posts, I’ve explained the differences between TokuMX replication and MongoDB replication, and why they are completely incompatible. In this (belated) post, I explain one last difference: the oplog format for operations. Specifically, TokuMX …


Multiple column index vs multiple indexes with MySQL 5.6

A question often comes when talking about indexing: should we use multiple column indexes or multiple indexes on single columns? Peter Zaitsev wrote about it back in 2008 and the conclusion then was that a multiple …


Why Unique Indexes are Bad

Before creating a unique index in TokuMX or TokuDB, ask yourself, “does my application really depend on the database enforcing uniqueness of this key?” If the answer is ANYTHING other than yes, do not declare …


The small improvements of MySQL 5.6: Duplicate Index Detection

Here at the MySQL Performance Blog, we’ve been discussing the several new features that MySQL 5.6 brought: GTID-based replication, InnoDB Fulltext, Memcached integration, a more complete performance schema, online DDL and several other InnoDB and …


MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown

While preparing the webinar I will deliver this Friday, I ran into a quite interesting (although not very impacting) optimizer issue: a “SELECT *” taking half the time to execute than the same “SELECT one_indexed_column” …


Full table scan vs full index scan performance

Earlier this week, Cédric blogged about how easy we can get confused between a covering index and a full index scan in the EXPLAIN output. While a covering index (seen with EXPLAIN as Extra: Using …


Building Indexes by Sorting In Innodb (AKA Fast Index Creation)

Innodb can indexes built by sort since Innodb Plugin for MySQL 5.1 which is a lot faster than building them through insertion, especially for tables much larger than memory and large uncorrelated indexes you might …


Partitioning, Free Lunches, & Indexing, Part 2

Review In part one, I presented a very brief and particular view of partitioning. I covered what partitioning is, with hardly a mention of why one would use partitioning. In this post, I’ll talk about …


Extending Index for Innodb tables can hurt performance in a surprising way

One schema optimization we often do is extending index when there are queries which can use more key part. Typically this is safe operation, unless index length increases dramatically queries which can use index can …