18.05.2018 19:44, Vlad Khorsun via Firebird-devel wrote:
All,
I going to merge into master implementation of pool of external connections.
The feature was initially developed more than a year ago, and works at
production
with good feedback.
According to discussion in this topic i made following changes:
- New system privilege MODIFY_EXT_CONN_POOL to manage pool properties (instead
of
initiallly used 'ALTER DATABASE' user right).
- New session management statement ALTER SESSION RESET is implemented (see
CORE-5832).
Ticket is not marked as closed for a while as i want to make sure
implementation
is complete. Thus any suggestions, notes, etc are welcome.
I still have some questions to agree (or not):
- Should connections pool always use ALTER SESSION RESET when connection become
idle ?
At first looks - yes, it should. It allows to make (almost) no difference for
user
code with non-pooled connections. But from practical POV i have some doubts
and want
to discuss it here:
- pre v4 Firebird versions have no such statement and it will fail (of course
connections pool should handle it correctly)
- it adds at least one additional network roundtrip which could be
unnecessary if
user code doesn't alter session and not uses GTT ON COMMIT PRESERVE on
remote side.
For some applications it could add too much performance penalty for nothing
- At tracker there was proposition to add new database trigger ON RESET which
should
fire when ALTER SESSION RESET is run. Should we implement it ?
- If i missed something else - please tell me.
Please, read and comment:
https://github.com/FirebirdSQL/firebird/blob/ExternalConnectionsPool/doc/sql.extensions/README.external_connections_pool
It was updated according to suggestions in this topic.
Regards,
Vlad
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