Increase max columns per key to 32

Registered by rich prohaska on 2013-10-24

(Blueprint obsoleted by Rich's request)

Queries sometimes get much better performance when the index that is used covers the query. Storage engines like InnoDB and TokuDB store the primary key as part of the secondary key. When a query needs the values of columns that are not in the key, the storage engine does a primary key lookup for each secondary key read. This can really tank performance.

MySQL supports 16 columns per key. This patch increases the number of columns per key to 32, which allows one to increase the scope of queries that are covered by the secondary key.

https://github.com/Tokutek/mysql56/commit/8e439302d1ef6556e780677fc2f1b65bb59c745c
and
https://github.com/Tokutek/mysql56/commit/9b8d9d5599f2c674a62cb6e426671e20011086d8

Blueprint information

Status:
Not started
Approver:
Laurynas Biveinis
Priority:
Not
Drafter:
None
Direction:
Needs approval
Assignee:
None
Definition:
New
Series goal:
None
Implementation:
Unknown
Milestone target:
None

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