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MDEV-21117: refine the server binlog-based recovery for semisync

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Problem:
=======
When the semisync master is crashed and restarted as slave it could
recover transactions that former slaves may never have seen.
A known method existed to clear out all prepared transactions
with --tc-heuristic-recover=rollback does not care to adjust
binlog accordingly.

Fix:
===
The binlog-based recovery is made to concern of the slave semisync role of
post-crash restarted server.
No changes in behavior is done to the "normal" binloggging server
and the semisync master.

When the restarted server is configured with
  --rpl-semi-sync-slave-enabled=1
the refined recovery attempts to roll back prepared transactions
and truncate binlog accordingly.
In case of a partially committed (that is committed at least
in one of the engine participants) such transaction gets committed.
It's guaranteed no (partially as well) committed transactions
exist beyond the truncate position.
In case there exists a non-transactional replication event
(being in a way a committed transaction) past the
computed truncate position the recovery ends with an error.

As after master crash and failover to slave, the demoted-to-slave
ex-master must be ready to face and accept its own (generated by)
events, without generally necessary --replicate-same-server-id.
So the acceptance conditions are relaxed for the semisync slave
to accept own events without that option.
While gtid_strict_mode ON ensures no duplicate transaction can be
(re-)executed the master_use_gtid=none slave has to be
configured with --replicate-same-server-id.

*NOTE* for reviewers.

This patch does not handle the user XA which is done
in next git commit.
This commit is contained in:
Sujatha
2020-04-09 20:45:45 +05:30
committed by Andrei Elkin
parent 82c07b178a
commit 6c39eaeb12
25 changed files with 2619 additions and 127 deletions
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53
mysql-test/suite/binlog/r/binlog_truncate_multi_log.result Normal file
View File

@@ -0,0 +1,53 @@
call mtr.add_suppression("Can.t init tc log");
call mtr.add_suppression("Aborting");
SET @@global.max_binlog_size= 4096;
RESET MASTER;
FLUSH LOGS;
CREATE TABLE ti (a INT PRIMARY KEY, b MEDIUMTEXT) ENGINE=Innodb;
CREATE TABLE tm (a INT PRIMARY KEY, b MEDIUMTEXT) ENGINE=MyISAM;
connect master1,localhost,root,,;
"List of binary logs before rotation"
show binary logs;
Log_name File_size
master-bin.000001 #
master-bin.000002 #
INSERT INTO ti VALUES(1,"I am gonna survive");
INSERT INTO tm VALUES(1,"me too!");
SET DEBUG_SYNC= "commit_after_release_LOCK_after_binlog_sync SIGNAL master1_ready WAIT_FOR con1_go";
INSERT INTO ti VALUES (2, REPEAT("x", 4100));
connect master2,localhost,root,,;
SET DEBUG_SYNC= "now WAIT_FOR master1_ready";
SET DEBUG_SYNC= "commit_before_get_LOCK_commit_ordered SIGNAL master2_ready WAIT_FOR master2_go";
INSERT INTO ti VALUES (3, "not gonna survive");
connection default;
SET DEBUG_SYNC= "now WAIT_FOR master2_ready";
"List of binary logs before crash"
show binary logs;
Log_name File_size
master-bin.000001 #
master-bin.000002 #
master-bin.000003 #
# The gtid binlog state prior the crash will be truncated at the end of the test
SELECT @@global.gtid_binlog_state;
@@global.gtid_binlog_state
0-1-6
connection default;
# Kill the server
disconnect master1;
disconnect master2;
# restart: --rpl-semi-sync-slave-enabled=1
FOUND 1 /truncated binlog file:.*master.*000002/ in mysqld.1.err
"One record should be present in table"
SELECT * FROM ti;
a b
1 I am gonna survive
# The truncated gtid binlog state
SELECT @@global.gtid_binlog_state;
@@global.gtid_binlog_state
0-1-4
SELECT @@global.gtid_binlog_pos;
@@global.gtid_binlog_pos
0-1-4
# Cleanup
DROP TABLE ti;
# End of the tests