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Re: GUC assign hooks (was Re: wal_buffers = -1 and SIGHUP)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Bernd Helmle <mailings(at)oopsware(dot)de>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: GUC assign hooks (was Re: wal_buffers = -1 and SIGHUP)
Date: 2011-04-03 23:16:32
Message-ID: 20513.1301872592@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Sun, Apr 3, 2011 at 1:26 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> IMO the real problem is essentially that GUC assign hooks have two
>> functions, checking and canonicalization of the value-to-be-stored
>> versus executing secondary actions when an assignment is made; and
>> there's no way to get at just the first one.

> Yes, I think that's right.  A related point is that the API for assign
> hooks is not consistent across all data types: string assign hooks can
> return a replacement value, whereas everyone else can only succeed or
> fail.

Right.  In the original design we only foresaw the need to canonicalize
string values, so that's why it's like that.  This change will make it
more consistent.

			regards, tom lane

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