MySQL Forums
Forum List  »  Performance

Re: order by primary key slowly
Posted by: Peter Brawley
Date: April 07, 2016 10:20AM

> It is obvious that the second option takes longer than the first query
> since it needs to read more than 5 times as many index entries ...

What confuses us users is that Explain suggests the opposite: it will read 5,465,723 rows for the quicker query, 1,000,010 for the slower one. Explain fails to explain that the PK index is slower to read.

> and in addition sort all the IDs.

Yes.

Options: ReplyQuote


Subject
Views
Written By
Posted
1049
April 05, 2016 10:42PM
503
April 06, 2016 10:15AM
486
April 06, 2016 11:23AM
560
April 06, 2016 08:11PM
454
April 06, 2016 10:35PM
465
April 07, 2016 12:34AM
Re: order by primary key slowly
487
April 07, 2016 10:20AM
468
April 07, 2016 11:26PM
469
April 12, 2016 07:42PM
469
April 06, 2016 08:57AM
464
April 06, 2016 10:17AM


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.