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Before commit6112853cdain MySQL 4.1.1 introduced the parameter innodb_file_per_table, all InnoDB data was written to the InnoDB system tablespace (often named ibdata1). A serious design problem is that once the system tablespace has grown to some size, it cannot shrink even if the data inside it has been deleted. There are also other design problems, such as the server hang MDEV-29930 that should only be possible when using innodb_file_per_table=0 and innodb_undo_tablespaces=0 (storing both tables and undo logs in the InnoDB system tablespace). The parameter innodb_change_buffering was deprecated in commitb5852ffbee. Starting with commitbaf276e6d4(MDEV-19229) the number of innodb_undo_tablespaces can be increased, so that the undo logs can be moved out of the system tablespace of an existing installation. If all these things (tables, undo logs, and the change buffer) are removed from the InnoDB system tablespace, the only variable-size data structure inside it is the InnoDB data dictionary. DDL operations on .ibd files was optimized in commit86dc7b4d4c(MDEV-24626). That should have removed any thinkable performance advantage of using innodb_file_per_table=0. Since there should be no benefit of setting innodb_file_per_table=0, the parameter should be deprecated. Starting with MySQL 5.6 and MariaDB Server 10.0, the default value is innodb_file_per_table=1.
64 lines
2.1 KiB
Text
64 lines
2.1 KiB
Text
-- source include/have_innodb.inc
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-- source include/have_innodb_16k.inc
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--echo #
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--echo # Bug#15923864 (Bug#67718):
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--echo # INNODB DRASTICALLY UNDER-FILLS PAGES IN CERTAIN CONDITIONS
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--echo #
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# InnoDB should try to insert to the next page before split,
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# if the insert record for split_and_insert is last of the page.
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# Otherwise, the follwing records 999,998,997 cause each page per record.
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#
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CREATE TABLE t1 (a BIGINT PRIMARY KEY, b VARCHAR(4096)) ENGINE=InnoDB;
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INSERT INTO t1 VALUES (0, REPEAT('a', 4096));
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INSERT INTO t1 VALUES (1000, REPEAT('a', 4096));
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INSERT INTO t1 VALUES (1001, REPEAT('a', 4096));
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INSERT INTO t1 VALUES (1002, REPEAT('a', 4096));
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INSERT INTO t1 VALUES (1, REPEAT('a', 4096));
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INSERT INTO t1 VALUES (2, REPEAT('a', 4096));
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# | 0, 1, 2 | 1000, 1001, 1002|
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SELECT page_number, number_records
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FROM information_schema.innodb_sys_tablespaces s1,
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information_schema.innodb_buffer_page s2
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WHERE s1.space = s2.space AND name = 'test/t1'
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AND page_type = "INDEX" ORDER BY page_number;
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INSERT INTO t1 VALUES (999, REPEAT('a', 4096));
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# try to insert '999' to the end of '0,1,2' page, but no space
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# the next '1000,1001,1002' page has also no space.
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# | 0, 1, 2 | 999 | 1000, 1001, 1002|
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SELECT page_number, number_records
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FROM information_schema.innodb_sys_tablespaces s1,
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information_schema.innodb_buffer_page s2
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WHERE s1.space = s2.space AND name = 'test/t1'
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AND page_type = "INDEX" ORDER BY page_number;
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INSERT INTO t1 VALUES (998, REPEAT('a', 4096));
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# try to insert to the end of '0,1,2' page, but no space
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# the next '998' page has space.
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# | 0, 1, 2 | 998, 999 | 1000, 1001, 1002|
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SELECT page_number, number_records
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FROM information_schema.innodb_sys_tablespaces s1,
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information_schema.innodb_buffer_page s2
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WHERE s1.space = s2.space AND name = 'test/t1'
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AND page_type = "INDEX" ORDER BY page_number;
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INSERT INTO t1 VALUES (997, REPEAT('a', 4096));
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# same
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# | 0, 1, 2 | 997, 998, 999 | 1000, 1001, 1002|
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SELECT page_number, number_records
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FROM information_schema.innodb_sys_tablespaces s1,
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information_schema.innodb_buffer_page s2
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WHERE s1.space = s2.space AND name = 'test/t1'
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AND page_type = "INDEX" ORDER BY page_number;
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DROP TABLE t1;
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