Bug #44803 | Join performance with large tables is way too slow | ||
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Submitted: | 11 May 2009 20:48 | Modified: | 20 Dec 2009 17:11 |
Reporter: | norbert van Nobelen | Email Updates: | |
Status: | No Feedback | Impact on me: | |
Category: | MySQL Server | Severity: | S2 (Serious) |
Version: | 5.1.31, 6.0.10-apha | OS: | Linux (OpenSuse 10.3) |
Assigned to: | CPU Architecture: | Any | |
Tags: | join, query, slow |
[11 May 2009 20:48]
norbert van Nobelen
[12 May 2009 4:42]
Valeriy Kravchuk
Do you have indexes on uuid column of your tables?
[12 May 2009 19:10]
norbert van Nobelen
In the case I create the two temp tables to join them: No indexes: Joining 200000 (all records from table 1) records against 80000 (all records from table 2) looks to me like full table scans are the most efficient way and indexes should be pretty much redundant. In the case of just direct join with subqueries used: The main selection criteria are indexed, the uuid is derived from UUID() and is not indexed (I can not create indexes on subquery data).
[20 Nov 2009 17:11]
Valeriy Kravchuk
Please, send the results of EXPLAIN for your queries. Send your my.cnf file content also.
[21 Dec 2009 0:00]
Bugs System
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