database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-31 17:02:12 +03:00
Code Activity

Remove the single-argument form of string_agg(). It added nothing much in

Browse Source 
functionality, while creating an ambiguity in usage with ORDER BY that at
least two people have already gotten seriously confused by.  Also, add an
opr_sanity test to check that we don't in future violate the newly minted
policy of not having built-in aggregates with the same name and different
numbers of parameters.  Per discussion of a complaint from Thom Brown.
This commit is contained in:
Tom Lane
2010-08-05 18:21:19 +00:00
parent fd1843ff89
commit b0c451e145
11 changed files with 85 additions and 77 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
doc/src/sgml/syntax.sgml
View File

@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.149 2010/08/04 15:27:57 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.150 2010/08/05 18:21:17 tgl Exp $ -->
<chapter id="sql-syntax">
<title>SQL Syntax</title>
@@ -1583,16 +1583,17 @@ SELECT array_agg(a ORDER BY b DESC) FROM table;
<para>
When dealing with multiple-argument aggregate functions, note that the
<literal>ORDER BY</> clause goes after all the aggregate arguments.
For example, this:
For example, write this:
<programlisting>
SELECT string_agg(a, ',' ORDER BY a) FROM table;
</programlisting>
not this:
<programlisting>
SELECT string_agg(a ORDER BY a, ',') FROM table; -- not what you want
SELECT string_agg(a ORDER BY a, ',') FROM table; -- incorrect
</programlisting>
The latter syntax will be accepted, but <literal>','</> will be
treated as a (useless) sort key.
The latter is syntactically valid, but it represents a call of a
single-argument aggregate function with two <literal>ORDER BY</> keys
(the second one being rather useless since it's a constant).
</para>
<para>