Horton

Re: Proposal: Implement failover on libpq connect level.

Kevin Grittner <kgrittn@ymail.com>

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From: Kevin Grittner <kgrittn@ymail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Bruce Momjian <bruce@momjian.us>, "Shulgin, Oleksandr" <oleksandr.shulgin@zalando.de>, Andres Freund <andres@anarazel.de>, Alvaro Herrera <alvherre@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Albe Laurenz <laurenz.albe@wien.gv.at>, Victor Wagner <vitus@wagner.pp.ru>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2015-09-09T20:30:49Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> wrote:

> I think the problem we should be trying to solve is: Given a set
> of server IPs, connect to one that is up.
>
> I believe this comes up in several different scenarios.
>
> Example #1: [single server; changing IP address gracefully]
>
> Example #2: [xDB/BDR client uses local master if up; else a remote]
>
> Example #3: [SR/HS with changing primary]

For all of those it is clear that we do not need (or want!)
heartbeat, STONITH, fencing, etc. to be handled by the connector.
If the above are the sorts of problems we are trying to solve, a
very simple solution is the best.  I know you outlined several; I'm
not sure it would matter all that much which one we used -- any
would work and someone should Just Do It.

> I'm sure there are more.

Ay, there's the rub.  Some people seemed to be suggesting that this
should be far more than what you describe above.  That would, IMO,
be a mistake.

--
Kevin Grittner
EDB: 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.