MySQL事物系列:3:innodb_flush_log_at_trx_commit小实验
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1:创建表和存储过程
mysql> create database trx; Query OK, 1 row affected (0.02 sec) mysql> USE trx Database changed mysql> CREATE TABLE test_trx( -> id int(5), -> uname char(30)) -> engine =innodb; Query OK, 0 rows affected (0.01 sec) mysql> DROP PROCEDURE IF EXISTS pro_trx $$ Query OK, 0 rows affected (0.00 sec) mysql> DELIMITER $$ mysql> DROP PROCEDURE IF EXISTS pro_trx $$ Query OK, 0 rows affected, 1 warning (0.00 sec) mysql> CREATE PROCEDURE pro_trx(count int UNSIGNED) -> BEGIN -> DECLARE fir INT UNSIGNED DEFAULT 1; -> DECLARE sec CHAR(50) DEFAULT REPEAT(‘id‘,50); -> WHILE fir <= count -> DO -> INSERT INTO test_trx SELECT null,fir; -> COMMIT; -> SET fir = fir+1; -> END WHILE; -> END; -> $$ Query OK, 0 rows affected (0.00 sec) mysql> DELIMITER ;
2:
mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 1 | +--------------------------------+-------+ 1 row in set (0.00 sec)
设置为0
mysql> SET GLOBAL innodb_flush_log_at_trx_commit = 0; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 0 | +--------------------------------+-------+ 1 row in set (0.00 sec)
mysql> CALL pro_trx(100000); Query OK, 0 rows affected (10.20 sec)
设置为1:
mysql> SET GLOBAL innodb_flush_log_at_trx_commit =1; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 1 | +--------------------------------+-------+ 1 row in set (0.00 sec)
mysql> CALL pro_trx(100000); Query OK, 0 rows affected (4 min 45.12 sec)
设置为2:
mysql> SET GLOBAL innodb_flush_log_at_trx_commit = 2; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 2 | +--------------------------------+-------+ 1 row in set (0.00 sec)
mysql> CALL pro_trx(100000); Query OK, 0 rows affected (13.80 sec)
重新设置为0:观察下
mysql> SET GLOBAL innodb_flush_log_at_trx_commit = 0; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 0 | +--------------------------------+-------+ 1 row in set (0.00 sec)
mysql> CALL pro_trx(100000); Query OK, 0 rows affected (10.25 sec)
innodb_flush_log_at_trx_commit设置为不同的值,性能差别很明显。
可以通过设置为0或者2来提高事物提高性能。但是这种设置丧失了ACID特性。而针对上述存储过程,为了提高事物的提交性能,应该在将10万行记录插入表后进行一次的COMMIT操作。而不是每插入一条就提交一次。这样做的优点是事物可以回滚到最初的状态。
2:改写一下存储过程
mysql> DELIMITER $$ mysql> DROP PROCEDURE IF EXISTS pro_trx_one_commit$$ Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> CREATE PROCEDURE pro_trx_one_commit(count int UNSIGNED) -> BEGIN -> DECLARE fir INT UNSIGNED DEFAULT 1; -> DECLARE sec CHAR(50) DEFAULT REPEAT(‘id‘,50); -> WHILE fir <=count -> DO -> INSERT INTO test_trx SELECT null,fir; -> SET fir = fir+1; -> END WHILE; -> COMMIT; -> END; -> $$ Query OK, 0 rows affected (0.00 sec) mysql> DELIMITER ;
innodb_flush_log_at_trx_commit 设置为0:
mysql> SET GLOBAL innodb_flush_log_at_trx_commit = 0; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 0 | +--------------------------------+-------+ 1 row in set (0.00 sec)
mysql> CALL pro_trx_one_commit(100000); Query OK, 0 rows affected (10.19 sec)
innodb_flush_log_at_trx_commit 设置为1:
mysql> SET GLOBAL innodb_flush_log_at_trx_commit = 1; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 1 | +--------------------------------+-------+ 1 row in set (0.00 sec)
mysql> CALL pro_trx_one_commit(100000); Query OK, 0 rows affected (5 min 27.33 sec)
innodb_flush_log_at_trx_commit 设置为2:
mysql> CALL pro_trx_one_commit(100000); Query OK, 0 rows affected (13.50 sec)
3:再次改写存储过程
mysql> DELIMITER $$ mysql> CREATE PROCEDURE pro_trx_no_commit(count int UNSIGNED) -> BEGIN -> DECLARE fir INT UNSIGNED DEFAULT 1; -> DECLARE sec CHAR(50) DEFAULT REPEAT(‘id‘,50); -> WHILE fir <=count -> DO -> INSERT INTO test_trx SELECT null,fir; -> SET fir = fir+1; -> END WHILE; -> END; -> $$ Query OK, 0 rows affected (0.00 sec) mysql> DELIMITER ;
mysql> SET GLOBAL innodb_flush_log_at_trx_commit = 1; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%innodb_flush_log_at_trx_commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | innodb_flush_log_at_trx_commit | 1 | +--------------------------------+-------+ 1 row in set (0.00 sec)
mysql> CALL pro_trx_no_commit(100000) ; Query OK, 1 row affected (4 min 55.05 sec)
mysql> SHOW VARIABLES LIKE ‘%commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | autocommit | ON | | innodb_commit_concurrency | 0 | | innodb_flush_log_at_trx_commit | 1 | +--------------------------------+-------+ 3 rows in set (0.00 sec)
mysql> SET GLOBAL autocommit = OFF; Query OK, 0 rows affected (0.00 sec) mysql> SHOW VARIABLES LIKE ‘%commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | autocommit | ON | | innodb_commit_concurrency | 0 | | innodb_flush_log_at_trx_commit | 1 | +--------------------------------+-------+ 3 rows in set (0.00 sec) 另外开一个连接 mysql> SHOW VARIABLES LIKE ‘%commit%‘; +--------------------------------+-------+ | Variable_name | Value | +--------------------------------+-------+ | autocommit | OFF | | innodb_commit_concurrency | 0 | | innodb_flush_log_at_trx_commit | 1 | +--------------------------------+-------+ 3 rows in set (0.00 sec)
把自动提交关掉之后重新调用存储过程查看性能:
mysql> CALL pro_trx_no_commit(100000); Query OK, 1 row affected (2.66 sec)
mysql> USE trx Database changed mysql> CALL pro_trx_no_commit(100000); Query OK, 1 row affected (2.66 sec) mysql> CALL pro_trx_one_commit(100000); Query OK, 0 rows affected (2.48 sec) mysql> CALL pro_trx(100000); Query OK, 0 rows affected (4 min 47.90 sec)
MySQL事物系列:3:innodb_flush_log_at_trx_commit小实验
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本文系统来源:http://www.cnblogs.com/xiaoit/p/4554048.html
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