| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Cc: | Anastasia Lubennikova <a(dot)lubennikova(at)postgrespro(dot)ru>, Greg Nancarrow <gregn4422(at)gmail(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, "Smith, Peter" <peters(at)fast(dot)au(dot)fujitsu(dot)com>, David Steele <david(at)pgmasters(dot)net>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)fujitsu(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>, Dave Cramer <pg(at)fastcrypt(dot)com>, Jing Wang <jingwangian(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Elvis Pranskevichus <elprans(at)gmail(dot)com> |
| Subject: | Re: Libpq support to connect to standby server as priority |
| Date: | 2020-11-24 23:19:47 |
| Message-ID: | 325979.1606259987@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)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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