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Re: array_agg() NULL Handling

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 (view raw or flat)
Thread:
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 &mdash; 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 &mdash; 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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