Bug #43 | Join does not use indexes in case there is no cardinarity data | ||
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Submitted: | 27 Jan 2003 18:54 | Modified: | 3 Oct 2008 9:47 |
Reporter: | Peter Zaitsev (Basic Quality Contributor) | Email Updates: | |
Status: | Can't repeat | Impact on me: | |
Category: | MySQL Server: Optimizer | Severity: | S3 (Non-critical) |
Version: | 3.23, 4.0 | OS: | Any (all) |
Assigned to: | CPU Architecture: | Any | |
Tags: | qc |
[27 Jan 2003 18:54]
Peter Zaitsev
[28 Jan 2003 17:00]
MySQL Developer
Not a bug, but a not critical ptimizer issue, as this is only relevant for small tables (which are fast anyway) Nothing to be done at this stage
[27 Sep 2008 8:42]
Konstantin Osipov
mysql> explain select * from a,b,c where t=1 and a=b and b=c\G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: a type: ref possible_keys: a,t key: t key_len: 5 ref: const rows: 1 Extra: *************************** 2. row *************************** id: 1 select_type: SIMPLE table: b type: ref possible_keys: b key: b key_len: 5 ref: test.a.a rows: 2 Extra: *************************** 3. row *************************** id: 1 select_type: SIMPLE table: c type: ref possible_keys: c key: c key_len: 5 ref: test.a.a rows: 2 Extra: 3 rows in set (0.00 sec) I believe I can't repeat it any more. My version is 6.0. Re-opening to be re-verified, since I'm not sure I'm reading explain output correctly.
[3 Oct 2008 9:47]
Valeriy Kravchuk
Not repeatable with recent 6.0.x and 5.1.x.