From: | "David E(dot) Wheeler" <david(at)kineticode(dot)com> |
---|---|
To: | PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: array_agg() NULL Handling |
Date: | 2010-09-01 16:08:04 |
Message-ID: | F9D43A22-AB3F-4329-BF65-C9E7CD4A3400@kineticode.com |
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Lists: | pgsql-hackers |
On Sep 1, 2010, at 12:30 AM, Pavel Stehule wrote:
>> So are the docs right, or is array_agg() right?
>
> Docs is wrong :) I like current implementation. You can remove a NULLs
> from aggregation very simply, but different direction isn't possible
Patch:
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index 9f91939..e301019 100644
*** a/doc/src/sgml/syntax.sgml
--- b/doc/src/sgml/syntax.sgml
*************** sqrt(2)
*** 1543,1549 ****
The first form of aggregate expression invokes the aggregate
across all input rows for which the given expression(s) yield
non-null values. (Actually, it is up to the aggregate function
! whether to ignore null values or not — but all the standard ones do.)
The second form is the same as the first, since
<literal>ALL</literal> is the default. The third form invokes the
aggregate for all distinct values of the expressions found
--- 1543,1550 ----
The first form of aggregate expression invokes the aggregate
across all input rows for which the given expression(s) yield
non-null values. (Actually, it is up to the aggregate function
! whether to ignore null values or not — but all the standard
! ones except <function>array_agg</> do.)
The second form is the same as the first, since
<literal>ALL</literal> is the default. The third form invokes the
aggregate for all distinct values of the expressions found
Best,
David
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