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Re: MySQL 5.7 : InnoDB. 2 Deletes query using index but... too many rows locked and cause deadlock
Posted by: Olivier Dasini
Date: July 18, 2019 03:52AM

Thanks!

Regarding cid_operation table.
because ID is your primary key and you're using InnoDB you can replace index:
UNIQUE KEY `id_id_env_case` (`ID_ENV_CASE`,`ID`),
by
UNIQUE KEY `id_id_env_case` (`ID_ENV_CASE`)

in other words `id_id_env_case` (`ID_ENV_CASE`) == `id_id_env_case` (`ID_ENV_CASE`,`ID`)
and
`id_id_env_case` (`ID_ENV_CASE`,`ID`) == `id_id_env_case` (`ID_ENV_CASE`,`ID`, ID)
https://dev.mysql.com/doc/refman/5.7/en/innodb-index-types.html


Further more this index could be benefit for the other delete that is probably the root cause of the deadlock.

Could you also send the explain for the second query ?
There is probably something to win there

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