All COM_STMT_SEND_LONG_DATA commands and the COM_STMT_EXECUTE that follows
it must be sent to the same server. This implicitly works for masters but
with multiple slave servers the data could be sent to the wrong server.
By using the code added for MXS-2521, this problem can now be easily
solved by checking what the previous command was.
If a transaction replay fails, no queries must be routed before the
connection is closed. This could happen if the client received the error
from the replay failure and closes the connection before the fake hangup
generated by the replay failure is processed.
When fake hangup events are delivered via DCBs, the current DCB would not
be updated. This would cause error messages without a session ID which
makes failure analysis harder.
If code that may remove items from m_nodes_by_id (Clustrix nodes
keyed by id) succeeds, we must update the vector of health check
URLs also in the case that code that _may_ add items to m_nodes_by_id
fails.
The error was only generated for COM_STMT_EXECUTE commands when all PS
commands should trigger it. In addition, large packets would get sent two
errors upon the arrival of the trailing end.
If an error is generated while a COM_CHANGE_USER is being done, it would
always use the sequence number 1. To properly handle this case and send
the correct sequence number, the COM_CHANGE_USER progress needs to be
tracked at the session level.
The information needs to be shared between the backend and client
protocols as the final OK to the COM_CHANGE_USER, with the sequence number
3, is the one that the backend server returns. Only after this response
has been received and routed to the client can the COM_CHANGE_USER
processing stop.
If a server fails mid-resultset, there's not a lot we can do to recover
the situation. A few cases could be handled (e.g. generate an ERR if the
resultset has proceeded to the row processing stage) but these fall
outside the scope of the original issue.
As is explained in MDEV-19893:
Client reads from socket, gets the packet from 1. with seqno=0, which
it does not expect, since seqno is supposed to be incremented. Client
complains, throws tantrums and exceptions.
To cater for clients that do not expect out-of-bound messages
(i.e. server-initiated packets with seqno 0), all messages generated by
MaxScale should use at least sequence number 1.
Deep-copying prevents subsequent modifications done by the caller from
affecting the data that can be potentially stored in the write queue of
the backend's DCB.
It was possible that a one-second outage that caused immediate rejection
of network connections would cause all of the query retry attempts to fail
within a very short period of time. By preventing rapid reconnections,
query_retries is more effective as an error filtering mechanism.
Centos6 uses a very old version of SQLite without support for URI filenames.
PAM authenticator must use a file-based database.
Commit cherry-picked to 2.4.0 from 2.3.
If a COM_STMT_EXECUTE has no metadata in it and it has more than one
parameter, it must be routed to the same backend where the previous
COM_STMT_EXECUTE with the same ID was routed to. This prevents MDEV-19811
that is triggered by MaxScale routing the queries to different backends.
mxs::Buffer::iterator is not a random-access iterator and hence will have
linear cost. This is too costly to do on every packet with even moderately
sized resultsets.
Due to there being no distinction between a temporarily stopped worker and
a permanently stopped one, we must allow posting of messages to stopped
workers.
