MySQL Forums
Forum List  »  Performance

Re: Very slow query when too many joins
Posted by: Rick James
Date: July 20, 2016 09:37AM

James...
Each 'attribute' (field_id:value pair) needs a JOIN to look up (for a given ads_id).
(His original posting said "183" twice, that was probably a typo.)

The large number of JOINs is one of the evils of EAV schema design. (The index I suggested makes them faster.)

The slowdown at 26 joins is another evil. (The setting I suggested may help with that.)

The bottom line is that EAV does not scale and should be avoided. He needs 29 or so lookups. With JSON, only 1 is needed. Instead, the application splits apart the JSON and formats the output. But that is much faster.

Options: ReplyQuote


Subject
Views
Written By
Posted
4497
June 05, 2016 09:17AM
1694
June 05, 2016 09:27AM
1317
June 05, 2016 10:48AM
1310
June 05, 2016 03:33PM
1158
June 06, 2016 02:23AM
1130
June 06, 2016 03:33AM
1166
June 06, 2016 09:02AM
1072
June 06, 2016 11:30AM
1097
June 06, 2016 02:11PM
Re: Very slow query when too many joins
1146
July 20, 2016 09:37AM


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.