Re: Patch: Implement failover on libpq connect level.

From: Catalin Iacob <iacobcatalin(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Peter van Hardenberg <pvh(at)pvh(dot)ca>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Patch: Implement failover on libpq connect level.
Date: 2016-11-16 17:00:42
Message-ID: CAHg_5gpzNZK6PYBf4mrSHt+ywgBV5wSR-2BNvVZRwSjgtYRfHw@mail.gmail.com
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On Wed, Nov 16, 2016 at 2:50 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> Hmm, let's go back to the JDBC method, then. "show
> transaction_read_only" will return true on a standby, but presumably
> also on any other non-writable node. You could even force it to be
> true artificially if you wanted to force traffic off of a node, using
> ALTER {SYSTEM|USER ...|DATABASE ..} SET default_transaction_read_only
> = on
>
> I think that would address Alvaro's concern, and it's nicer anyway if
> libpq and JDBC are doing the same thing.

Not sure I agree that using this is a good idea in the first place.

But if we end up using this, I really think the docs should be very
explicit about what's implemented and not just say master/any. With
the master/any docs in the patch I would be *very* surprised if a
master is skipped only because it was configured with
default_transaction_read_only = on.

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