Re: shared-memory based stats collector - Mailing list pgsql-hackers

From Andres Freund
Subject Re: shared-memory based stats collector
Date
Msg-id 20180706185750.b6h5cwif53zfieu7@alap3.anarazel.de
Whole thread Raw
In response to Re: shared-memory based stats collector  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: shared-memory based stats collector  ("Joshua D. Drake" <jd@commandprompt.com>)
Re: shared-memory based stats collector  (Magnus Hagander <magnus@hagander.net>)
List 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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