MySQL Forums :: Performance :: Wrong estimation of Rows in explain


Advanced Search

Re: Wrong estimation of Rows in explain
Posted by: Rathi Rao ()
Date: August 02, 2016 05:48AM

Hi Rick,

Apologies for the delayed response.

That many a data is needed and unfortunately I do not have any where conditions to filter the data

Would you please help me understand how is the row estimate correct? Should'nt it show the total number of rows in the table?

Also, with the join such as a.col1 = b.col1 and a.col2 = b.col2, which one would be better?

Separate indexes on each of the columns a.col1, a.col2 , b.col2 and b.col1

or

composite indexes on (a.col1,a.col2) and (b.col1,b.col2) ??

Thanks in advance
Rathi

Options: ReplyQuote


Subject Views Written By Posted
Wrong estimation of Rows in explain 550 Rathi Rao 07/27/2016 06:19AM
Re: Wrong estimation of Rows in explain 273 Peter Brawley 07/27/2016 08:55AM
Re: Wrong estimation of Rows in explain 308 Rathi Rao 07/27/2016 11:58PM
Re: Wrong estimation of Rows in explain 292 Peter Brawley 07/28/2016 09:14AM
Re: Wrong estimation of Rows in explain 294 Rathi Rao 07/29/2016 05:11AM
Re: Wrong estimation of Rows in explain 285 Peter Brawley 07/29/2016 01:10PM
Re: Wrong estimation of Rows in explain 295 Rick James 07/29/2016 06:58PM
Re: Wrong estimation of Rows in explain 268 Rathi Rao 08/02/2016 05:48AM
Re: Wrong estimation of Rows in explain 289 Rick James 08/02/2016 06:23PM
Re: Wrong estimation of Rows in explain 267 Rathi Rao 08/02/2016 05:38AM
Re: Wrong estimation of Rows in explain 295 james wang 08/04/2016 05:31AM


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.