Re: which is best for JOIN approach
Hi,
I assume that you have indexes on all your id columns.
For the second alternative, the join order is given: a -> b -> ec
For the first alternative, both the join order above and a -> ec -> b is possible.
Whether the processing ec before b is beneficial depends on the size of the tables, and the number of matching ids in the two tables.
In other words, I would choose the first alternative because it gives the Query Optimizer more alternatives to evaluate.
Øystein Grøvlen,
Senior Principal Software Engineer,
MySQL Group, Oracle,
Trondheim, Norway
Subject
Views
Written By
Posted
1529
November 24, 2015 09:39AM
Re: which is best for JOIN approach
921
November 25, 2015 02:14AM
952
November 25, 2015 02:42AM
945
November 29, 2015 11:53AM
868
February 19, 2016 05:28AM
810
February 21, 2016 04:56PM
873
February 19, 2016 05:31AM
763
February 21, 2016 01:40PM
815
February 21, 2016 01:43PM
834
February 25, 2016 05:50AM
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.