[pgpool-hackers: 1713] More fail over tolerate session control

[Tatsuo Ishii]

Now that Pgpool-II 3.6's session control will be more tolerate against
fail over than before (if the load balance node was not the downed
node), I would like to be more aggressive regarding this.

One idea is, if the load balance node has been changed to other than
the down node, the session would not be disconnected in the fail over
event. Currently the only chance to change the load balance node is,
after the session terminated. Apparently this does not help my
objective. If we could change the load balance node after PostgreSQL
sends "ready for query" message, it seems we could reach the
goal. This strategy will work mostly well with simple query
protocol. However, if PREPARE is used or extended protocol is used and
prepared statement has been sent to the load balance node, we can not
switch to other node unless we move or copy the prepared statement to
the node since changing the load balance node will be a disaster.

Any idea to solve this?

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp