[pgpool-hackers: 2225] Seamless application failover

[Tatsuo Ishii]

I have a little bit thought about one of the new feature candidates
item #63:
http://pgpool.net/mediawiki/index.php/pgpool-II_3.7_development

This is similar to Oracle's "Transparent application failover"
(TAF). In TAF, following session properties will migrate from old
session to new session:

1) Open cursors

2) Prepared statements (and portals in PostgreSQL world)

3) Remaining data row set if SELECT is processing while failover

4) and others (PL/SQL state for example)

Plus we need to restore all modified GUC variables in the old session.

I think none of these are possible without some help from PostgreSQL
backend thus we need to propose such that enhancement to PostgreSQL
first.

In short, this feature is not technically possible to implement for
now.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp