Documented readconnroute and schemarouter router diagnostics. The
duplicated fields that are already in the general service diagnostic
output are not documented with the hopes that they can be eventually
removed.
When a temporary table is created with a multi-statement query, it won't
be detected by MaxScale.
Also removed the wrong limitations section from the document.
causal_reads does not work with servers that update their state via
mechanisms other than the standard replication. In practice this is just
another Galera limitation.
The settings "match", "exclude" and "options" are now explained once
in the general documentation. The individual filter documentation refers
to the general explanation.
The documentation stated that MVCC reads weren't safe with
transaction_replay when in reality they are not safe in general and
transaction_replay has no effect on it.
Queries such as SHOW TABLES FROM db1 are now routed to the backend with db1.
This gives the correct result as long as db1 is not sharded to multiple
backends.
The lazy connection creation reduces the burden that short sessions place
on the backend servers. This also prevents the problems caused by early
disconnections that happen when only one server is used but multiple
connections are created. This does not solve the problem (MXS-619) but it
does mitigate it to acceptable levels.
This commit also adds a change to the weighting algorithm that prefers
existing connections over unopened ones. This helps avoid the
flip-flopping that happens when the absolute scores are very similar. The
hard-coded value might need to be tuned once testing is done.
This commit adds a new parameter that, when enabled, prunes the session
command history to a known length. This makes it possible to keep a
client-side pooled connection open indefinitely at the cost of making
reconnections theoretically unsafe. In practice the maximum history length
can be set to a value that encompasses a single session using the pooled
connection with no risk to session state integrity. The default history
length of 50 commands is quite likely to be adequate for the majority of
use-cases.
Both the replication lag and the message printing state are saved in SERVER,
although the values are mostly used by readwritesplit. A log message is printed
both when a server goes over the limit and when it comes back below.
Because of concurrency issues, a message may be printed multiple times before
different threads detect the new message state.
Documentation updated to explain the change.
