Details
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Bug
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Status: Closed (View Workflow)
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Minor
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Resolution: Fixed
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5.1.67, 5.2.14
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None
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None
Description
Rows_examined in the slow query log can be reset by the outer query when using a sub query. For these two queries the first one sets Rows_examined correctly but the second one has it reset even though the row stats work correctly.
# Time: 110702 9:44:23
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# User@Host: [ebergen] @ localhost []
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# Thread_id: 1 Schema: test QC_hit: No
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# Query_time: 1.396374 Lock_time: 0.000093 Rows_sent: 1 Rows_examined: 677984
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# Row_Stats: test:rows_read=677984,rows_changed=0,rows_changed_x_indexes=0;
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# Index_Stats: test:rows_read=677984;
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SET timestamp=1309625063; |
select count(*) from t2; |
# Time: 110702 9:44:49
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# User@Host: [ebergen] @ localhost []
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# Thread_id: 1 Schema: test QC_hit: No
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# Query_time: 2.262701 Lock_time: 0.000126 Rows_sent: 1 Rows_examined: 0
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# Row_Stats: test:rows_read=677984,rows_changed=0,rows_changed_x_indexes=0;#temp#:rows_read=0,rows_changed=677984,rows_changed_x_indexes=677984;
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# Index_Stats: test:rows_read=677984;
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SET timestamp=1309625089; |
select count(*) from (select 1 from t2) as t; |
The table I'm using looks like:
CREATE TABLE `t2` ( |
`t` bigint(20) DEFAULT NULL, |
`u` bigint(20) DEFAULT NULL, |
`b` text,
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KEY `t` (`t`) |
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |