Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.1(EOL)
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None
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Ubuntu
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2017-02, 10.1.22
Description
set global optimizer_switch="engine_condition_pushdown=on"
Ouch! It is now pulling back the entire table 200 rows at a time.
Query: SELECT DISTINCT x FROM table
PRIMARY KEY (x,y,z)
Backend queries: SELECT x FROM table x > 12345 ORDER BY x,y,z LIMIT 200.
(And it is taking much longer than when ecp=OFF)
Question 1: Why fetch the table rather than executing the query?
Question 2: When you have a multi-part PK, that code is likely to be "wrong". Note that it always compared only x, not y and z. And it always said 200.
Attachments
Issue Links
- causes
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MDEV-13282 post-fix for MDEV-8954
- Closed