From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Anastasia Lubennikova <a.lubennikova@postgrespro.ru>
Cc: Greg Nancarrow <gregn4422@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>
Cc: Smith, Peter <peters@fast.au.fujitsu.com>
Cc: David Steele <david@pgmasters.net>
Cc: Tsunakawa, Takayuki <tsunakawa.takay@fujitsu.com>
Cc: Haribabu Kommi <kommi.haribabu@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Dave Cramer <pg@fastcrypt.com>
Cc: Jing Wang <jingwangian@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Cc: Elvis Pranskevichus <elprans@gmail.com>
Subject: Re: Libpq support to connect to standby server as priority
Date: Tue, 24 Nov 2020 18:19:47 -0500
Message-ID: <325979.1606259987@sss.pgh.pa.us> (raw)
In-Reply-To: <20201124225917.GA21884@alvherre.pgsql>
References: <20201124225917.GA21884@alvherre.pgsql>
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> On 2020-Nov-24, Tom Lane wrote:
>>> As it stands, 0001 reduces the ParameterStatus message traffic to
>>> at most one per GUC per query, but it doesn't attempt to eliminate
>>> duplicate ParameterStatus messages altogether. We could do that
>>> as a pretty simple adjustment if we're willing to expend the storage
>>> to remember the last value sent to the client. It might be worth
>>> doing, since for example the function-SET-clause case would typically
>>> lead to no net change in the GUC's value by the end of the query.
>> On reflection this seems worth doing, since excess client traffic
>> is far from free.
> Agreed. If this is just a few hundred bytes of server-side local memory
> per backend, it seems definitely worth it.
Yeah, given the current set of GUC_REPORT variables, it's hard to see
the storage for their last-reported values amounting to much. The need
for an extra pointer field in each GUC variable record might eat more
space than the actually-live values :-(
regards, tom lane
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Subject: Re: Libpq support to connect to standby server as priority
In-Reply-To: <325979.1606259987@sss.pgh.pa.us>
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