Emergency

Search Results for: what fields should i index

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: …

Read More
 

Introducing TokuMX Clustering Indexes for MongoDB

Since introducing TokuMX, we’ve discussed benefits that TokuMX has for existing MongoDB applications that require no changes. In this post, I introduce an extension we’ve made to the indexing API: clustering indexes, a tool that …

Read More
 

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 …

Read More
 

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 …

Read More
 

Covering Indexes: How many indexes do you need?

I’ve recently been blogging about how partitioning is a poor man’s answer to covering indexes. I got the following comment from Jaimie Sirovich: “There are many environments where you could end up creating N! indices …

Read More
 

Recover BLOB fields

For a long time long types like BLOB, TEXT were not supported by Percona InnoDB Recovery Tool. The reason consists in a special way InnoDB stores BLOBs. An InnoDB table is stored in a clustered …

Read More
 

InnoDB TABLE/INDEX stats

In Released and new coming features I did not mentioned two additional INFORMATION_SCHEMA tables available in XtraDB: It is INNODB_TABLE_STATS INNODB_INDEX_STATS These table show statistics about InnoDB tables ( taken from InnoDB data dictionary). INNODB_TABLE_STATS …

Read More
 

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 …

Read More
 

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 …

Read More
 

Advanced Query Tuning in MySQL 5.6 and MySQL 5.7 Webinar: Q&A

Thank you for attending my July 22 webinar titled “Advanced Query Tuning in MySQL 5.6 and 5.7” (my slides and a replay available here). As promised here is the list of questions and my answers …

Read More