Horton

Re: Patch: Implement failover on libpq connect level.

Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>

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From: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>
To: 'Mithun Cy' <mithun.cy@enterprisedb.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Peter van Hardenberg <pvh@pvh.ca>, Peter Eisentraut <peter_e@gmx.net>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2016-11-15T01:09:55Z
Lists: pgsql-hackers 
From: pgsql-hackers-owner@postgresql.org
> [mailto:pgsql-hackers-owner@postgresql.org] On Behalf Of Mithun Cy
> Thanks, my concern is suppose you have 3 server in cluster A(new version),
> B(new version), C(old version). If we implement as above only new servers
> will send ParameterStatus message to indicate what type of server we are
> connected. Server C will not send same. So we will not be able to use new
> feature "failover to new master" for such a kind of cluster.

No, the streaming replication requires the same major release for all member servers, so there's no concern about the mixed-version cluster.

Sorry, pmState can only be used in postmaster.  In our context, postgres can use RecoveryInProgress().  Anyway, in addition to the reduced round trip, the libpq code would be much simpler.

Regards
Takayuki Tsunakawa

Commits

  1. libpq: Add target_session_attrs parameter.

  2. Remove superuser checks in pgstattuple

  3. Fix unwanted flushing of libpq's input buffer when socket EOF is seen.