Re: Stable function semantics (was Re: Mislabeled timestamp functions)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Oliver Jowett <oliver(at)opencloud(dot)com>
Cc: Bruno Wolff III <bruno(at)wolff(dot)to>, Gaetano Mendola <mendola(at)bigfoot(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Stable function semantics (was Re: Mislabeled timestamp functions)
Date: 2004-10-03 21:27:25
Message-ID: 7887.1096838845@sss.pgh.pa.us
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Oliver Jowett <oliver(at)opencloud(dot)com> writes:
> Bruno Wolff III wrote:
>> I should have said within a single statement instead of within a single
>> transaction.

> As I understand Tom's earlier explanation of this, the definition is
> even more narrow: stable functions only need to return the same value
> across a single tablescan.

> It might be useful to have some variant of stable (or perhaps just a
> change in semantics) such that the function returns the same value for
> identical parameters until the next CommandCounterIncrement.

In practice I think these are equivalent definitions.

regards, tom lane

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