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Problem: ======== We have a Master/Master Setup on two servers, but are only writing to one of those servers (so it is essentially Master/Slave) We upgraded from 10.1.* to 10.2.22 last week and starting with the upgrade, we are getting duplicate key errors on the slave. BINLOG=mixed. Analysis: ========= This issue happens with LOCK TABLES and binlog_format=MIXED combination. When an UNSAFE statement is encountered in 'MIXED' mode, it is logged in the form of 'ROW' format. For all the tables that are part of LOCK TABLES list their table maps are written into the binary log. For each table in the list a check is done to see if 'check_table_binlog_row_based_done' flag is set or not. If it is not set a check process is initiated to see if table qualifies for row based binary logging or not and 'check_table_binlog_row_based_done' is set. This flag will be cleared at the time of closing thread tables. But there can be special cases where the LOCK TABLES contains more number of tables but the unsafe query is actually using subset of tables from LOCK TABLES list. For example: LOCK TABLES locks t1,t2,t3 but the unsafe statement makes use of only two tables t1,t3. In this case the 'check_table_binlog_row_based_done' flag is enabled for table 't2' while writing table map, but 'close_thread_tables' function call will not reset this flag. Since the flag is not cleared for table 't2' even a safe statement which used t2 will be logged in the form of row based format. This leads to an assert on debug builds and causes duplicate entries in release builds. In release builds a statement is logged in the form of both ROW and STATEMENT format. This causes the slave to fail with duplicate key error. Fix: === During 'close_thread_tables' when LOCK TABLE modes are active "ha_reset" is done for all the tables which were part of current statement. As mentioned in the example 'ha_reset' is called for tables 't1' and 't3'. This will clear the 'check_table_binlog_row_based_done' flag. At this point add a check for the rest of the tables to see if 'check_table_binlog_row_based_done' is enabled or not. If enabled clear the flag.
29 lines
1.2 KiB
Text
29 lines
1.2 KiB
Text
include/master-slave.inc
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[connection master]
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CREATE TABLE t1 (id mediumint(8) unsigned NOT NULL AUTO_INCREMENT, someLabel varchar(30) NOT NULL, flag tinyint(1) NOT NULL DEFAULT 0, PRIMARY KEY (id)) Engine=MyISAM;
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CREATE TABLE t2 (id mediumint(8) unsigned NOT NULL AUTO_INCREMENT, data varchar(30) NOT NULL, status tinyint(1) NOT NULL, PRIMARY KEY (id)) Engine=MyISAM;
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CREATE TABLE t3 (id mediumint(8) unsigned NOT NULL AUTO_INCREMENT, t1id mediumint(8) unsigned NOT NULL, flag tinyint(1) NOT NULL DEFAULT 0, status tinyint(1) NOT NULL DEFAULT 0, PRIMARY KEY (id)) Engine=MyISAM;
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INSERT INTO t1 ( id, someLabel, flag ) VALUES ( 1, 'ABC', 0 );
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CREATE OR REPLACE TRIGGER doNothing
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BEFORE UPDATE ON t1
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FOR EACH ROW
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BEGIN
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IF
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new.someLabel != old.someLabel
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THEN
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UPDATE t3 SET t3.flag = 0;
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END IF;
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END|
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FLUSH LOGS;
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LOCK TABLES t1 WRITE, t2 WRITE;
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INSERT INTO t2 (data, status) VALUES ('1', 4);
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UPDATE t1 SET flag = 1 WHERE id = 1;
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INSERT INTO t2 (data, status) VALUES ('2', 4);
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UNLOCK TABLES;
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connection slave;
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include/diff_tables.inc [master:t1, slave:t1]
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include/diff_tables.inc [master:t2, slave:t2]
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include/diff_tables.inc [master:t3, slave:t3]
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connection master;
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DROP TABLE t1, t2, t3;
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include/rpl_end.inc
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