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MDEV-28461 semisync-slave server recovery fails to rollback prepared transaction

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that is not in binlog.

Post-crash recovery of --rpl-semi-sync-slave-enabled server
failed to recognize a transaction in-doubt that needed rolled back.
A prepared-but-not-in-binlog transaction gets committed instead
to possibly create inconsistency with a master (e.g the way it was observed
in the bug report).

The semisync recovery is corrected now with initializing binlog coordinates
of any transaction in-doubt to the maximum offset which is
unreachable.
In effect when a prepared transaction that is not found in binlog
it will be decided to rollback because it's guaranteed to reside
in a truncated tail area of binlog.

Mtr tests are reinforced to cover the described scenario.
This commit is contained in:
Andrei
2022-05-11 13:12:48 +03:00
committed by Sergei Golubchik
parent e03e72234a
commit 98ca71ab28
6 changed files with 119 additions and 25 deletions
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15
mysql-test/suite/binlog/t/binlog_truncate_active_log.inc
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@@ -1,6 +1,7 @@
connect(master1,localhost,root,,);
connect(master2,localhost,root,,);
connect(master3,localhost,root,,);
connect(master4,localhost,root,,);
--connection default
@@ -22,16 +23,26 @@ SET DEBUG_SYNC= "commit_before_get_LOCK_after_binlog_sync SIGNAL master2_ready";
SET DEBUG_SYNC= "now WAIT_FOR master2_ready";
SELECT @@global.gtid_binlog_pos as 'Before the crash';
--connection master4
# Simulate prepared & not-logged trx; it will never recover.
SET DEBUG_SYNC= "ha_commit_trans_before_log_and_order SIGNAL master4_ready WAIT_FOR signal_never_arrives";
--send INSERT INTO t4 VALUES (13)
--connection master3
SET DEBUG_SYNC= "now WAIT_FOR master4_ready";
SELECT @@global.gtid_binlog_pos as 'Before the crash and never logged trx';
--connection default
--source include/kill_mysqld.inc
--disconnect master1
--disconnect master2
--disconnect master3
--disconnect master4
#
# Server restart
#
--let $restart_parameters= --rpl-semi-sync-slave-enabled=1 --sync-binlog=1
--let $restart_parameters= --rpl-semi-sync-slave-enabled=1 --sync-binlog=1 --log-warnings=3
--source include/start_mysqld.inc
# Check error log for a successful truncate message.
@@ -49,6 +60,8 @@ SELECT @@global.gtid_binlog_pos as 'Before the crash';
SELECT @@global.gtid_binlog_pos as 'After the crash';
--echo "One row should be present in table 't'"
SELECT * FROM t;
--echo "No row should be present in table 't4'"
SELECT * FROM t4;
# prepare binlog file index for the next test
--inc $binlog_file_index