MySQL Forums
Forum List  »  Optimizer & Parser

Re: Slow DELETE-Statement since update on 5.7
Posted by: Øystein Grøvlen
Date: March 19, 2018 01:15PM

In MySQL 5.7, derived tables (subqueries in FROM clause) is automatically merged into the outer query. It is not apparent to me why that should be a problem in your case, but you can turn off this feature by setting

optimizer_switch='derived_merge=off'

If that works, it would be interesting to see the EXPLAIN output both with and without this setting. That could tell us more about what is going on.

Øystein Grøvlen,
Senior Principal Software Engineer,
MySQL Group, Oracle,
Trondheim, Norway

Options: ReplyQuote


Subject
Views
Written By
Posted
Re: Slow DELETE-Statement since update on 5.7
220
March 19, 2018 01:15PM


Sorry, you can't reply to this topic. It has been closed.

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.