Bug #56925 | Wrong execution of UPDATE … WHERE sec_key=… ORDER BY pk DESC | ||
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Submitted: | 22 Sep 2010 11:27 | Modified: | 2 Feb 2011 14:25 |
Reporter: | Marko Mäkelä | Email Updates: | |
Status: | Verified | Impact on me: | |
Category: | MySQL Server: Optimizer | Severity: | S3 (Non-critical) |
Version: | 5.5 | OS: | Any |
Assigned to: | Assigned Account | CPU Architecture: | Any |
Tags: | regression |
[22 Sep 2010 11:27]
Marko Mäkelä
[30 Oct 2010 23:00]
Bugs System
No feedback was provided for this bug for over a month, so it is being suspended automatically. If you are able to provide the information that was originally requested, please do so and change the status of the bug back to "Open".
[2 Feb 2011 14:18]
Marko Mäkelä
The manifestation of this bug is performance: instead of performing a key lookup, the optimizer is asking for all records smaller than key. A key lookup could take advantage of the InnoDB adaptive hash index.
[5 Feb 2011 0:15]
Omer Barnir
triage: setting tag to SR55MRU (I2 performance regression, D3 not clear the extent of the regression)
[25 Mar 2011 19:52]
Rick James
Since this is InnoDB, isn't the index effectively (c1_idx, pk) ? So the comment "WHERE and ORDER BY clauses cannot be satisfied by the same index" should be irrelevant? Perhaps it is significant that DESC is used in the ORDER BY?