Details
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Task
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Status: Open (View Workflow)
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Major
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Resolution: Unresolved
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None
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None
Description
Any query to information_schema is extremely slow because it scans all databases. For example, this query takes over 3 seconds. This bug has been fixed in MySQL 8.0, so I tested in that version using the same data and this same query takes 0.03 seconds.
https://bugs.mysql.com/bug.php?id=81347
SELECT `update_time` FROM information_schema.tables;
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...
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5068 rows in set (3.289 sec)
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EXPLAIN SELECT update_time FROM information_schema.tables;
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+------+-------------+--------+------+---------------+------+---------+------+------+----------------------------------------+
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| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
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+------+-------------+--------+------+---------------+------+---------+------+------+----------------------------------------+
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| 1 | SIMPLE | tables | ALL | NULL | NULL | NULL | NULL | NULL | Open_full_table; Scanned all databases |
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+------+-------------+--------+------+---------------+------+---------+------+------+----------------------------------------+
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1 row in set (0.002 sec)
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Attachments
Issue Links
- relates to
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MDEV-11655 Transactional data dictionary
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- Open
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