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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10.4.24
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None
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CentOS 7 Source build
Description
Documentation at https://mariadb.com/kb/en/innodb-online-ddl-operations-with-the-instant-alter-algorithm/#alter-table-drop-index-and-drop-index states that 10.4 supports DROP INDEX ..., ALGORITHM=INSTANT, but it does not.
This is what I get when I run the example from that URL:
MariaDB [(none)]> \s
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--------------
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./bin/mysql Ver 15.1 Distrib 10.4.24-MariaDB, for Linux (x86_64) using readline 5.1
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Connection id: 8
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Current database:
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Current user: bdempsey@localhost
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SSL: Cipher in use is DHE-RSA-AES256-GCM-SHA384
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Current pager: stdout
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Using outfile: ''
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Using delimiter: ;
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Server: MariaDB
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Server version: 10.4.24-MariaDB-debug Source distribution
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Protocol version: 10
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Connection: Localhost via UNIX socket
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Server characterset: latin1
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Db characterset: latin1
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Client characterset: utf8
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Conn. characterset: utf8
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UNIX socket: /home/bdempsey/mariadb/10.2/data/mysql.sock
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Uptime: 1 min 8 sec
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Threads: 6 Questions: 4 Slow queries: 0 Opens: 17 Flush tables: 1 Open tables: 10 Queries per second avg: 0.058
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MariaDB [foo]> CREATE OR REPLACE TABLE tab (
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-> a int PRIMARY KEY,
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-> b varchar(50),
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-> c varchar(50),
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-> INDEX b_index (b)
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-> );
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Query OK, 0 rows affected (0.053 sec)
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MariaDB [foo]> SET SESSION alter_algorithm='INSTANT';
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Query OK, 0 rows affected (0.000 sec)
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MariaDB [foo]> ALTER TABLE tab DROP INDEX b_index;
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ERROR 1846 (0A000): ALGORITHM=INSTANT is not supported. Reason: DROP INDEX. Try ALGORITHM=NOCOPY
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Attachments
Issue Links
- relates to
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MDEV-13134 Introduce ALTER TABLE attributes ALGORITHM=NOCOPY and ALGORITHM=INSTANT
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- Closed
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- mentioned in
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Page Failed to load
Because DROP INDEX will take time proportional to the size of the index (to traverse not the index tree, but the linked list of allocated page numbers), it does not belong to the ALGORITHM=INSTANT subset of ALGORITHM=INPLACE. It is allowed by ALGORITHM=NOCOPY.
The unfortunately named ALGORITHM=INPLACE allows the table to be rebuilt (copied), while ALGORITHM=NOCOPY does not allow that. A name like ALGORITHM=ENGINE would have been more appropriate for the generic native ALTER TABLE.