pgsql: Document evaluation-order considerations for aggregate functions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-committers(at)postgresql(dot)org
Subject: pgsql: Document evaluation-order considerations for aggregate functions
Date: 2014-11-14 22:20:08
Message-ID: E1XpPDs-0000Yn-P4@gemulon.postgresql.org
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Document evaluation-order considerations for aggregate functions.

The SELECT reference page didn't really address the question of when
aggregate function evaluation occurs, nor did the "expression evaluation
rules" documentation mention that CASE can't be used to control whether
an aggregate gets evaluated or not. Improve that.

Per discussion of bug #11661. Original text by Marti Raudsepp and Michael
Paquier, rewritten significantly by me.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/0ce627d465f534a3234750a5b398664dfece4102

Modified Files
--------------
doc/src/sgml/ref/select.sgml | 36 ++++++++++++++++++++++++++----------
doc/src/sgml/syntax.sgml | 22 ++++++++++++++++++++++
2 files changed, 48 insertions(+), 10 deletions(-)

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