Horton

Re: Patch: Implement failover on libpq connect level.

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>
Cc: Mithun Cy <mithun.cy@enterprisedb.com>, Peter van Hardenberg <pvh@pvh.ca>, Peter Eisentraut <peter_e@gmx.net>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2016-11-15T14:36:46Z
Lists: pgsql-hackers 
On Mon, Nov 14, 2016 at 8:09 PM, Tsunakawa, Takayuki
<tsunakawa.takay@jp.fujitsu.com> wrote:
> 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.

True, but there is a concern about a newer libpq connecting to older
servers.  If we mimic what JDBC is already doing, we'll be compatible
and you'll be able to use this feature with a v10 libpq without
worrying about whether the target server is also v10.  If we invent
something new on the server side, then you'll need to be sure you have
both a v10 libpq and v10 server.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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.