Horton

Re: Patch: Implement failover on libpq connect level.

Craig Ringer <craig@2ndquadrant.com>

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From: Craig Ringer <craig@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>, 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: 2016-11-19T01:23:43Z
Lists: pgsql-hackers 
On 19 November 2016 at 01:29, Robert Haas <robertmhaas@gmail.com> wrote:

>> We can and probably should have both.
>>
>> If the server tells us on connect whether it's a standby or not, use that.
>>
>> Otherwise, ask it.
>>
>> That way we don't pay the round-trip cost and get the log spam when
>> talking to newer servers that send us something useful in the startup
>> packet, but we can still query it on older servers. Graceful fallback.
>>
>> Every round trip is potentially very expensive. Having libpq do them
>> unnecessarily is bad.
>
> True, but raising the bar for this feature so that it doesn't get done
> is also bad.  It can be improved in a later patch.

Good point. Starting with the followup query method seems fine.


-- 
 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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.