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Re: array_agg() NULL Handling

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: "David E(dot) Wheeler" <david(at)kineticode(dot)com>, Thom Brown <thom(at)linux(dot)com>, David Fetter <david(at)fetter(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: array_agg() NULL Handling
Date: 2010-09-01 18:46:00
Message-ID: 28700.1283366760@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> 2010/9/1 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> Well, you can build your own version of array_agg with the same
>> implementation, except you mark the transition function as strict ...

> I am checking this now, and it is not possible - it needs a some
> initial value and there isn't possible to set a "internal" value.

Well, you can cheat a bit ...

regression=# create or replace function array_agg_transfn_strict(internal, anyelement) returns internal as 'array_agg_transfn' language internal immutable;
CREATE FUNCTION
regression=# create aggregate array_agg_strict(anyelement) (stype = internal,
sfunc = array_agg_transfn_strict, finalfunc = array_agg_finalfn);
CREATE AGGREGATE
regression=# create or replace function array_agg_transfn_strict(internal, anyelement) returns internal as 'array_agg_transfn' language internal strict immutable;
CREATE FUNCTION

			regards, tom lane

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Subject: Re: array_agg() NULL Handling
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Subject: compiling with RELCACHE_FORCE_RELEASE doesn't pass regression

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