Re: Add min and max execute statement time in pg_stat_statement

From: Peter Eisentraut <peter_e(at)gmx(dot)net>
To: David G Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Add min and max execute statement time in pg_stat_statement
Date: 2015-02-18 01:21:32
Message-ID: 54E3E91C.4020105@gmx.net
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On 1/20/15 6:32 PM, David G Johnston wrote:
> In fact, as far as
> the database knows, the values provided to this function do represent an
> entire population and such a correction would be unnecessary. I guess it
> boils down to whether "future" queries are considered part of the population
> or whether the population changes upon each query being run and thus we are
> calculating the ever-changing population variance.

I think we should be calculating the population variance. We are
clearly taking the population to be all past queries (from the last
reset point). Otherwise calculating min and max wouldn't make sense.

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