RWBackend did not expect that a resultset and an unexpected ERR packet
could be stored in the same buffer. This can happen for example if a
server shuts down immediately after the resultset is sent.
If a packet with a KILL query was followed with another packet in the same
network buffer, the code wouldn't work as it expected to receive only one
packet at a time.
On RHEL8 the former may give rise to incorrect
error: 'char* strncpy(char*, const char*, size_t)' destination
unchanged after copying no bytes [-Werror=stringop-truncation]
In MaxScale, a "deprecated" parameter is not in use and can be ignored.
Leaving the parameters out of serialized configuration files avoids warning
messages.
Before the MXS-2250 fix, the following ends with an error:
CREATE TEMPORARY TABLE t (f INT);
DESCRIBE t;
Reason is that the first is sent to the master (and the table will
not be replicated to slaves) and the latter to some slave.
When a statement like 'DESCRIBE tbl' is classified, the table
name will now be available so that a router can check whether the
table is a temporary one. In that case, the statement must be sent
to the master.
By iterating over the servers and sending the master's charset we are
guaranteed a "known good" charset. This also solves the problem where a
deactivated server reference would be used as the charset and server
version source.
If the execution of a session command fails on a master, it is retried
again. If the master is not available, the response will be returned from
one of the slaves.
The retrying of a read on a slave should only be done when the failing
server is waiting for a result and it was the last server from which a
result was expected.
If the master fails when a session command is being executed with
delayed_retry enabled, a null query would get placed into the query
queue. This change simply prevents the crash and closes the session even
though the query could be retried.
The bug appears when a session command that is executed on the master
fails. The logic in the code doesn't take this case into consideration
when it processes failed connections.
A query should not be queued if no responses are expected. The code that
executes queued queries should be dead code and this assertion would catch
it.
