Emergency

Search Results for: loose index scan

Using UNION to implement loose index scan in MySQL

One little known fact about MySQL Indexing, however very important for successfull MySQL Performance Optimization is understanding when exactly MySQL is going to use index and how it is going to do them. So if …

Read More
 

Descending indexing and loose index scan

Comments to my previous posts, especially this one by Gokhan inspired me to write a bit about descending indexes and about loose index scan, or what Gokhan calls “better range” support. None of these are …

Read More
 

Parallel Query for MySQL with Shard-Query

While Shard-Query can work over multiple nodes, this blog post focuses on using Shard-Query with a single node.  Shard-Query can add parallelism to queries which use partitioned tables.  Very large tables can often be partitioned fairly …

Read More
 

Guidance for MySQL Optimizer Developers

I spend large portion of my life working on MySQL Performance Optimization and so MySQL Optimizer is quite important to me. For probably last 10 years I chased first Monty and later Igor with Optimizer …

Read More
 

MySQL: Followup on UNION for query optimization, Query profiling

Few days ago I wrote an article about using UNION to implement loose index scan. First I should mention double IN also works same way so you do not have to use the union. So …

Read More
 

A closer look at Percona Server 5.6

Yesterday we announced the GA release of Percona Server 5.6, the latest release of our enhanced, drop-in replacement for MySQL. Percona Server 5.6 is the best free MySQL alternative for demanding applications. Our third major …

Read More
 

MySQL Webinar: Advanced Query Tuning

On July 24 at 10 a.m. PDT, I will be delivering a Webinar on Advanced MySQL Query Tuning. I will focus on optimizing the common slow queries with group by and order by. Those queries …

Read More
 

MySQL and Percona Server in LinkBench benchmark

Around month ago Facebook has announced the Linkbench benchmark that models the social graph OLTP workload. Sources, along with a very nice description of how to setup and run this benchmark, can be found here. …

Read More
 

MySQL 5.5 and MySQL 5.6 default variable values differences

As the part of analyzing surprising MySQL 5.5 vs MySQL 5.6 performance results I’ve been looking at changes to default variable values. To do that I’ve loaded the values from MySQL 5.5.30 and MySQL 5.6.10 …

Read More
 

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 …

Read More