database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-25 01:02:05 +03:00
Code Activity

Note that the example aggregate array_accum is comparable to the now

Browse Source 
built-in array_agg.  Per suggestion from Robert Haas.
This commit is contained in:
Tom Lane
2008-11-20 21:10:44 +00:00
parent 170b66a0c5
commit 3d7ac0d0b1
1 changed files with 13 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
doc/src/sgml/xaggr.sgml
View File

@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/xaggr.sgml,v 1.35 2007/02/01 00:28:18 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/xaggr.sgml,v 1.36 2008/11/20 21:10:44 tgl Exp $ -->
<sect1 id="xaggr">
<title>User-Defined Aggregates</title>
@ -132,7 +132,10 @@ CREATE AGGREGATE array_accum (anyelement)
</programlisting>
Here, the actual state type for any aggregate call is the array type
having the actual input type as elements.
having the actual input type as elements. The behavior of the aggregate
is to concatenate all the inputs into an array of that type.
(Note: the built-in aggregate <function>array_agg</> provides similar
functionality, with better performance than this definition would have.)
</para>
<para>
@ -149,14 +152,14 @@ SELECT attrelid::regclass, array_accum(attname)
pg_tablespace | {spcname,spcowner,spclocation,spcacl}
(1 row)
SELECT attrelid::regclass, array_accum(atttypid)
SELECT attrelid::regclass, array_accum(atttypid::regtype)
FROM pg_attribute
WHERE attnum &gt; 0 AND attrelid = 'pg_tablespace'::regclass
GROUP BY attrelid;
attrelid | array_accum
---------------+-----------------
pg_tablespace | {19,26,25,1034}
---------------+---------------------------
pg_tablespace | {name,oid,text,aclitem[]}
(1 row)
</programlisting>
</para>