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c8ae357341
Lifted long standing limitation to the XA of rolling it back at the
transaction's
connection close even if the XA is prepared.
Prepared XA-transaction is made to sustain connection close or server
restart.
The patch consists of
- binary logging extension to write prepared XA part of
transaction signified with
its XID in a new XA_prepare_log_event. The concusion part -
with Commit or Rollback decision - is logged separately as
Query_log_event.
That is in the binlog the XA consists of two separate group of
events.
That makes the whole XA possibly interweaving in binlog with
other XA:s or regular transaction but with no harm to
replication and data consistency.
Gtid_log_event receives two more flags to identify which of the
two XA phases of the transaction it represents. With either flag
set also XID info is added to the event.
When binlog is ON on the server XID::formatID is
constrained to 4 bytes.
- engines are made aware of the server policy to keep up user
prepared XA:s so they (Innodb, rocksdb) don't roll them back
anymore at their disconnect methods.
- slave applier is refined to cope with two phase logged XA:s
including parallel modes of execution.
This patch does not address crash-safe logging of the new events which
is being addressed by MDEV-21469.
CORNER CASES: read-only, pure myisam, binlog-*, @@skip_log_bin, etc
Are addressed along the following policies.
1. The read-only at reconnect marks XID to fail for future
completion with ER_XA_RBROLLBACK.
2. binlog-* filtered XA when it changes engine data is regarded as
loggable even when nothing got cached for binlog. An empty
XA-prepare group is recorded. Consequent Commit-or-Rollback
succeeds in the Engine(s) as well as recorded into binlog.
3. The same applies to the non-transactional engine XA.
4. @@skip_log_bin=OFF does not record anything at XA-prepare
(obviously), but the completion event is recorded into binlog to
admit inconsistency with slave.
The following actions are taken by the patch.
At XA-prepare:
when empty binlog cache - don't do anything to binlog if RO,
otherwise write empty XA_prepare (assert(binlog-filter case)).
At Disconnect:
when Prepared && RO (=> no binlogging was done)
set Xid_cache_element::error := ER_XA_RBROLLBACK
*keep* XID in the cache, and rollback the transaction.
At XA-"complete":
Discover the error, if any don't binlog the "complete",
return the error to the user.
Kudos
-----
Alexey Botchkov took to drive this work initially.
Sergei Golubchik, Sergei Petrunja, Marko Mäkelä provided a number of
good recommendations.
Sergei Voitovich made a magnificent review and improvements to the code.
They all deserve a bunch of thanks for making this work done!
137 lines
4 KiB
Text
137 lines
4 KiB
Text
# ==== Purpose ====
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#
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# This test will generate two XA transactions on the master in a way that
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# they will block each other on the slave if the transaction isolation level
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# used by the slave applier is more restrictive than the READ COMMITTED one.
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#
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# Consider:
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# E=execute, P=prepare, C=commit;
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# 1=first transaction, 2=second transaction;
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#
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# Master does: E1, E2, P2, P1, C1, C2
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# Slave does: E2, P2, E1, P1, C1, C2
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#
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# The transactions are designed so that, if the applier transaction isolation
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# level is more restrictive than the READ COMMITTED, E1 will be blocked on
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# the slave waiting for gap locks to be released.
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#
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# Step 1
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#
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# The test will verify that the transactions don't block each other because
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# the applier thread automatically changed the isolation level.
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#
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# Step 2
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#
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# The test will verify that applying master's binary log dump in slave doesn't
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# block because mysqlbinlog is informing the isolation level to be used.
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#
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# ==== Related Bugs and Worklogs ====
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#
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# BUG#25040331: INTERLEAVED XA TRANSACTIONS MAY DEADLOCK SLAVE APPLIER WITH
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# REPEATABLE READ
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#
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--source include/have_debug.inc
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--source include/have_innodb.inc
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# The test case only make sense for RBR
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--source include/have_binlog_format_row.inc
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--source include/master-slave.inc
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--connection slave
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# To hit the issue, we need to split the data in two pages.
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# This global variable will help us.
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SET @saved_innodb_limit_optimistic_insert_debug = @@GLOBAL.innodb_limit_optimistic_insert_debug;
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SET @@GLOBAL.innodb_limit_optimistic_insert_debug = 2;
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#
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# Step 1 - Using async replication
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#
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# Let's generate the workload on the master
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--connection master
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CREATE TABLE t1 (
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c1 INT NOT NULL,
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KEY(c1)
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) ENGINE=InnoDB;
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CREATE TABLE t2 (
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c1 INT NOT NULL,
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FOREIGN KEY(c1) REFERENCES t1(c1)
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) ENGINE=InnoDB;
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INSERT INTO t1 VALUES (1), (3), (4);
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--connection master1
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XA START 'XA1';
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INSERT INTO t1 values(2);
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XA END 'XA1';
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# This transaction will reference the gap where XA1
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# was inserted, and will be prepared and committed
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# before XA1, so the slave will prepare it (but will
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# not commit it) before preparing XA1.
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--connection master
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XA START 'XA2';
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INSERT INTO t2 values(3);
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XA END 'XA2';
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# The XA2 prepare should be binary logged first
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XA PREPARE 'XA2';
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# The XA1 prepare should be binary logged
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# after XA2 prepare and before XA2 commit.
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--connection master1
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XA PREPARE 'XA1';
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# The commit order doesn't matter much for the issue being tested.
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XA COMMIT 'XA1';
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--connection master
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XA COMMIT 'XA2';
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# Everything is fine if the slave can sync with the master.
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--source include/sync_slave_sql_with_master.inc
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#
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# Step 2 - Using mysqlbinlog dump to restore the salve
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#
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--source include/stop_slave.inc
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DROP TABLE t2, t1;
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RESET SLAVE;
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RESET MASTER;
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--connection master
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--let $master_data_dir= `SELECT @@datadir`
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--let $master_log_file= query_get_value(SHOW MASTER STATUS, File, 1)
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--let $mysql_server= $MYSQL --defaults-group-suffix=.2
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--echo Restore binary log from the master into the slave
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--exec $MYSQL_BINLOG --force-if-open $master_data_dir/$master_log_file | $mysql_server
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--let $diff_tables= master:test.t1, slave:test.t1
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--source include/diff_tables.inc
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--let $diff_tables= master:test.t2, slave:test.t2
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--source include/diff_tables.inc
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#
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# Cleanup
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#
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--let $master_file= query_get_value(SHOW MASTER STATUS, File, 1)
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--let $master_pos= query_get_value(SHOW MASTER STATUS, Position, 1)
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DROP TABLE t2, t1;
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## When GTID_MODE=OFF, we need to skip already applied transactions
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--connection slave
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#--let $gtid_mode= `SELECT @@GTID_MODE`
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#if ($gtid_mode == OFF)
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#{
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# --disable_query_log
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# --disable_result_log
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# --eval CHANGE MASTER TO MASTER_LOG_FILE='$master_file', MASTER_LOG_POS=$master_pos
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# --enable_result_log
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# --enable_query_log
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#}
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--replace_result $master_file LOG_FILE $master_pos LOG_POS
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--eval CHANGE MASTER TO MASTER_LOG_FILE='$master_file', MASTER_LOG_POS=$master_pos
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SET @@GLOBAL.innodb_limit_optimistic_insert_debug = @saved_innodb_limit_optimistic_insert_debug;
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--source include/start_slave.inc
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--source include/rpl_end.inc
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