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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None
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None
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None
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2018-17, 2018-18, 2018-19, 2018-20, 2018-21, 2019-01, 2019-02
Description
GROUP BY handler processes every query not only that contains GROUP BY or aggregates in projection. Here is an output of the EXPLAIN for the simple SELECT that mustn't use GROUP BY handler for processing.
MariaDB [test]> explain extended select i from cs1;
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+---------------------------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+---------------------------------+
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| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | NULL | Storage engine handles GROUP BY |
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+---------------------------------+
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1 row in set, 1 warning (0.001 sec)
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But it must look like this:
MariaDB [test]> explain extended select i from cs1;
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------+
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| 1 | SIMPLE | cs1 | ALL | NULL | NULL | NULL | NULL | 2000 | 100.00 | |
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+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------+
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1 row in set, 1 warning (0.004 sec)
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Attachments
Issue Links
- relates to
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MCOL-1052 Implement GROUP BY pushdown support
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- Closed
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