Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Not a Bug
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10.1.18
Description
Let's say that we create a table that does not use page compression, and we insert some data:
CREATE TABLE `tab` (
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`id` int(11) NOT NULL,
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`str` varchar(50) DEFAULT NULL,
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PRIMARY KEY (`id`)
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) ENGINE=InnoDB DEFAULT CHARSET=latin1;
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INSERT INTO tab VALUES (1, 'str1');
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And then let's say that we want to enable page compression for this table:
SET GLOBAL innodb_compression_algorithm=zlib;
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ALTER TABLE tab PAGE_COMPRESSED=1;
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As pointed out in MDEV-11089, the table's existing uncompressed pages are not going to be compressed at this point:
MariaDB [db1]> SHOW GLOBAL STATUS LIKE 'Innodb_num_pages_page_compressed';
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+----------------------------------+-------+
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| Variable_name | Value |
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+----------------------------------+-------+
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| Innodb_num_pages_page_compressed | 0 |
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+----------------------------------+-------+
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1 row in set (0.00 sec)
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Since an OPTIMIZE TABLE rewrites the table, I would expect that executing that statement against the table would compress the existing uncompressed pages in the new copy, but it seems that it does not:
MariaDB [db1]> OPTIMIZE TABLE tab;
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+---------+----------+----------+-------------------------------------------------------------------+
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| Table | Op | Msg_type | Msg_text |
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+---------+----------+----------+-------------------------------------------------------------------+
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| db1.tab | optimize | note | Table does not support optimize, doing recreate + analyze instead |
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| db1.tab | optimize | status | OK |
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+---------+----------+----------+-------------------------------------------------------------------+
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2 rows in set (0.03 sec)
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|
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MariaDB [db1]> SHOW GLOBAL STATUS LIKE 'Innodb_num_pages_page_compressed';
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+----------------------------------+-------+
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| Variable_name | Value |
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+----------------------------------+-------+
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| Innodb_num_pages_page_compressed | 0 |
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+----------------------------------+-------+
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1 row in set (0.00 sec)
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Copying the table with ALTER TABLE has similar results:
MariaDB [db1]> ALTER TABLE tab ENGINE=InnoDB;
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Query OK, 0 rows affected (0.02 sec)
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Records: 0 Duplicates: 0 Warnings: 0
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MariaDB [db1]> SHOW GLOBAL STATUS LIKE 'Innodb_num_pages_page_compressed';
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+----------------------------------+-------+
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| Variable_name | Value |
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+----------------------------------+-------+
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| Innodb_num_pages_page_compressed | 0 |
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+----------------------------------+-------+
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1 row in set (0.00 sec)
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Attachments
Issue Links
- relates to
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- Closed
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