Re: Simple JOIN is extremely slow.
> # Jorgen: Interesting - key_len is still 4
Yes, there are not enough columns in the EXPLAIN output to spell out everything. The "4" says that is all that can be done with an eq_ref; "Using index" says that more stuff is used, but without any details. (Note: leaving out, say, `b` from that example would still "Using index".)
> # Rick: These are frustrating
> # Jorgen: Handler_read session status indicates that only one record is read
> in both cases. Maybe a more advanced test case is needed.
I left out a key prerequisite: There are a million rows with a=2. I believe it starts at the beginning of a=2, scans to the end, then backs up to find the one row.
Subject
Views
Written By
Posted
3053
June 10, 2011 10:34AM
1009
June 12, 2011 11:50AM
912
June 12, 2011 03:24PM
915
June 13, 2011 12:25PM
1892
June 13, 2011 12:07AM
1099
June 13, 2011 11:01AM
945
June 14, 2011 06:49AM
1002
June 14, 2011 08:04PM
1144
June 15, 2011 01:16AM
Re: Simple JOIN is extremely slow.
1001
June 15, 2011 07:38PM
934
June 15, 2011 11:42PM
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.