The test was missing a save_master_gtid.inc on the master,
leading to the slave thinking it was in sync after executing
sync_with_master_gtid.inc, despite not having executed the
latest transaction. This skipped transaction, XA COMMIT,
was supposed to error-to-be-ignored because its XID could not
be found, but be thrown out because the replication filters
would filter out the target database. However, if the slave
was able to stop before executing the transaction, then
the replication filer is reset (to empty), and when the
slave is later restarted, that transactions error would
no longer be ignored.
Additionally, as the test cases added in MDEV-33921 rely
on GTID synchronization, the test cases now force
master_use_gtid=slave_pos for consistency
There are two problems.
First, replication fails when XA transactions are used where the
slave has replicate_do_db set and the client has touched a different
database when running DML such as inserts. This is because XA
commands are not treated as keywords, and are thereby not exempt
from the replication filter. The effect of this is that during an XA
transaction, if its logged “use db” from the master is filtered out
by the replication filter, then XA END will be ignored, yet its
corresponding XA PREPARE will be executed in an invalid state,
thereby breaking replication.
Second, if the slave replicates an XA transaction which results in
an empty transaction, the XA START through XA PREPARE first phase of
the transaction won’t be binlogged, yet the XA COMMIT will be
binlogged. This will break replication in chain configurations.
The first problem is fixed by treating XA commands in
Query_log_event as keywords, thus allowing them to bypass the
replication filter. Note that Query_log_event::is_trans_keyword() is
changed to accept a new parameter to define its mode, to either
check for XA commands or regular transaction commands, but not both.
In addition, mysqlbinlog is adapted to use this mode so its
--database filter does not remove XA commands from its output.
The second problem fixed by overwriting the XA state in the XID
cache to be XA_ROLLBACK_ONLY, so at commit time, the server knows to
rollback the transaction and skip its binlogging. If the xid cache
is cleared before an XA transaction receives its completion command
(e.g. on server shutdown), then before reporting ER_XAER_NOTA when
the completion command is executed, the filter is first checked if
the database is ignored, and if so, the error is ignored.
Reviewed By:
============
Kristian Nielsen <knielsen@knielsen-hq.org>
Andrei Elkin <andrei.elkin@mariadb.com>
the only query of the XA transaction is on a non-transactional table
errors out:
XA BEGIN 'x';
--error ER_DUP_ENTRY
INSERT INTO t1 VALUES (1),(1);
XA END 'x';
XA PREPARE 'x';
The binlogging pattern is correctly started as expected with
the errored-out Query or its ROW format events, but there is
no empty XA_prepare_log_event group.
The following
XA COMMIT 'x';
therefore should not be logged either, but it does.
The bug is fixed with proper maintaining of a read-write binlog hton
property and use it to enforce correct binlogging decisions.
Specifically in the bug description case XA COMMIT won't be binlogged
in both when given in the same connection and externally after disconnect.
The same continue to apply to an empty XA that do not change any data in all
transactional engines involved.
