Index is not used for MyISAM table for SELECT+GROUP BY
Bug #1056699 reported by
Nilnandan Joshi
This bug affects 1 person
Affects | Status | Importance | Assigned to | Milestone | ||
---|---|---|---|---|---|---|
MySQL Server |
Unknown
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Unknown
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Percona Server moved to https://jira.percona.com/projects/PS | Status tracked in 5.7 | |||||
5.1 |
Won't Fix
|
Wishlist
|
Unassigned | |||
5.5 |
Triaged
|
Wishlist
|
Unassigned | |||
5.6 |
Triaged
|
Wishlist
|
Unassigned | |||
5.7 |
Triaged
|
Wishlist
|
Unassigned |
Bug Description
Two similar tables of InnoDB and MyISAM. Both tables contain the same type of indexes, structure and data every thing similar. one multicolumn index over 15 columns on each table for Select + Group By
Select col1,col2,
Group By col1,col2,
When I do EXPLAIN of the above query, InnoDB table uses multicolumn index. But the query over MyIsam table is not using the index. When I use FORCE INDEX for MyIsam, it worked.
I ran the query several times on table and measure time but query with FORCE INDEX is faster than normal one.
summary: |
- Covering index is not used for MyISAM table + Index is not used for MyISAM table for SELECT+GROUP BY |
tags: | added: upstream |
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