| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Magnus Hagander <magnus(at)hagander(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: shared-memory based stats collector |
| Date: | 2018-07-06 18:57:50 |
| Message-ID: | 20180706185750.b6h5cwif53zfieu7@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
On 2018-07-06 14:49:53 -0400, Robert Haas wrote:
> I think we also have to ask ourselves in general whether snapshots of
> this data are worth what they cost. I don't think anyone would doubt
> that a consistent snapshot of the data is better than an inconsistent
> view of the data if the costs were equal. However, if we can avoid a
> huge amount of memory usage and complexity on large systems with
> hundreds of backends by ditching the snapshot requirement, then we
> should ask ourselves how important we think the snapshot behavior
> really is.
Indeed. I don't think it's worthwhile major additional memory or code
complexity in this situation. The likelihood of benefitting from more /
better stats seems far higher than a more accurate view of the stats -
which aren't particularly accurate themselves. They don't even survive
crashes right now, so I don't think the current accuracy is very high.
Greetings,
Andres Freund
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