Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Duplicate
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1.2.1
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None
Description
There is a major performance degradation between 1.2 and 1.1. Here is the test bed.
MariaDB [test]> desc t1;
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+-------+--------+------+-----+---------+-------+
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| Field | Type | Null | Key | Default | Extra |
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+-------+--------+------+-----+---------+-------+
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| a | double | YES | | NULL | |
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| b | double | YES | | NULL | |
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+-------+--------+------+-----+---------+-------+
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2 rows in set (0.00 sec)
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MariaDB [test]> select count(*) from t1;
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+-----------+
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| count(*) |
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+-----------+
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| 560023752 |
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+-----------+
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1 row in set (2.46 sec)
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Version 1.1 timings for the query
MariaDB [test]> select max(a),max(b) from t1;
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selec count(*) from t1;
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+--------+--------+
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| max(a) | max(b) |
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+--------+--------+
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| 1 | 1 |
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+--------+--------+
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1 row in set (14.66 sec)
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1.2 timings for the query with the same hardware, standart lib, boost
MariaDB [test]> select max(a),max(b) from t1;
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selec count(*) from t1;
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+--------+--------+
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| max(a) | max(b) |
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+--------+--------+
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| 1 | 1 |
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+--------+--------+
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1 row in set (27.53 sec)
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According with the assembly transcript of the code the problem caused by excesive locking for atomic ref counter increase whilst running shared_pointer copy constructor in rowaggregation.cpp by RowAggregation::updateEntry().
Attachments
Issue Links
- duplicates
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- Closed
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