A non version specific executable comment, such as "/*! SELECT 1; */"
is during classification handled as if it would not be a comment. That
is, the contained statement will *always* be parsed.
A version specific executable comment, such as "/*!99999 CREATE PROCEDURE
bypass BEGIN */ SELECT ... " is during classification handled as it would
be a general comment. That is, the contained statement will *never* be
parsed.
In addition, in the latter case the parse result will never be better than
QC_QUERY_PARTIALLY_PARSED. The rationale is that since the comment is version
specific, we cannot know how the server will actually interpret the statement.
This will have an impact on the masking filter and the database firewall that
now will reject statements containing _version specific_ executable comments.
All servers are now updated in their own threads simultaneously. This
should reduce the possibility of having significantly different gtid:s
shown for different servers.
The functions are now in MonitorServer. Disk space can only be checked
during specific ticks. If a server misses a tick (e.g. is down) it will
be checked after disk_space_check_interval has passed.
If a result consists of only OK packets, they would be processed
recursively which most of the time leads to a stack overflow. This can be
prevented by consuming all OK packets in the result in one go.
- Check textual prepared statements for use of columns to be masked
in conjunction with functions.
- Check binary prepared statements for use of columns to be masked
in conjunction with functions.
- Prevent creation of textual prepared statement from variable.
As the masking filter must reject statements that use columns to be
masked as arguments to functions, a statement that cannot be fully
parsed must be rejected. Unless a statement can be fully parsed we
cannot know whether such usage occurs.
Syslog wasn't truncated which caused massive disk space usage when the
full test set was run. Also removed the creation of empty log files if no
messages were logged during the run.
By always setting the position of the next event, the replication cannot
break if the slave server has to reconnect after receiving an event that
was generated by the binlogfilter.
Using a std::deque to store the queries retains the exact state of the
object thus removing the need to parse the query again. It also removes
the need to split the queue into individual packets which makes the code
cleaner.
Moved the more verbose parts of the routing code into subfunctions and
arranged it so that more relevant parts are closer to each other. Also
added the SQL statement that is being delayed to the message.
When a readwritesplit session has a connection to a master server, servers
of the same rank as the master are used. If no master connection is
available, the server with the highest rank among all connected servers is
used. If there are no open connections, the server with the best rank is
chosen and a connection to it is made.
Connections with different rank values than what is the current rank value
of the session will be discarded. This reduces the use of server with
different ranks when the master server of a session fails. Without the
active pruning of connections, slave connections to primary clusters
without masters would remain in use even after the primary master
fails. This guarantees full switchover to a secondary cluster if a master
change occurs.
The rank can now only be used to define two groups of servers: primary and
secondary servers. This limits the exposure and reduces the number of
possibilities that can arise from the use of this parameter thus making it
more predictable.
The helper function makes it easier to convert enum values at runtime to
their integer representation. Also changed the configuration processing
code to use the new function.
If a master with a better rank and a slave with a worse rank were
available and master_accept_reads wasn't enabled, the slave would be
preferred over the master. The check for master_accept_reads was done
twice and also in the wrong place.
Although the default value is the maximum value of a signed 32-bit
integer, the value is stored as a 64-bit integer. The integer type
conversion functions return 64-bit values so storing it as one makes
sense.
Currently values higher than the default are allowed but the accepted
range of input should be restricted in the future.
Readwritesplit now respects server ranks. When servers are selected for
either routing or connection creation, the servers are partitioned by
their rank into sets of servers. These sets of servers are never mixed so
the end result is that only servers of the same rank are considered for
candidacy.
The master selection is slightly different: the server with the best rank
that is capable of acting as a master is chosen. This means that a session
can have a master with a lower rank and slaves with higher ranks than the
master. In most cases this actually is the preferred behavior as the rank
is used to prioritize usage but not outright prevent it.
The connection creation is now internal to RWSplitSession. This makes the
code more readable by removing the need to pass parameters and allowing
easier reuse of existing functions. The various conditions require to
create connections are now also checked in only one place.
Readwritesplit now picks the best available master if no open master
connection is available. This is required if the server rank is to be
taken into account when master selection is done.
Given the following query:
PREPARE ps FROM 'PREPARE ps2 FROM \'SELECT 1\'';
The debug assertion is hit even though this is valid, albeit unsupported,
SQL. An optimization would be to ignore the query if the prepared
statement type is another prepared statement.
When a single GWBUF was split into two with gwbuf_split, the new GWBUF
would point to the start of the shared data and the old one to the
end. Data-wise, this is fine but as the parsing info for queries is stored
in the shared buffer it causes problems when multiple packets get read in
one network payload. The end result would be that only the first query in
the lot would get parsed and the rest would get the same classification as
the first one.
To properly fix this without the need to deep clone the buffer would
require a reorganization of the buffer mechanism in MaxScale.
This commit alone doesn't fix the queued query routing problems in
readwritesplit. The commit from 2.2 which fixes the ordering problems with
queued queries is also required for a fully functional queued query
mechanism.
If a routing of a queued query caused it to be put back on the query
queue, the order in which the queue was reorganized was wrong. The first
query would get appended as the last query which caused the order to be
reversed.
