From 3379fae6de5994b242cedfa48cf613ecfee3db24 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Thu, 13 Nov 2008 15:59:51 +0000
Subject: [PATCH] array_agg aggregate function, as per SQL:2008, but without
ORDER BY clause
Rearrange the documentation a bit now that array_agg and xmlagg have similar
semantics and issues.
best of Robert Haas, Jeff Davis, Peter Eisentraut
---
doc/src/sgml/func.sgml | 85 ++++++++++++++++++++-----
src/backend/catalog/sql_features.txt | 2 +-
src/backend/utils/adt/array_userfuncs.c | 34 +++++++++-
src/include/catalog/catversion.h | 4 +-
src/include/catalog/pg_aggregate.h | 5 +-
src/include/catalog/pg_proc.h | 9 ++-
src/include/utils/array.h | 5 +-
src/test/regress/expected/arrays.out | 36 +++++++++++
src/test/regress/sql/arrays.sql | 7 ++
9 files changed, 164 insertions(+), 23 deletions(-)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 85403e2c9f7..20443f2b288 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.457 2008/11/12 13:09:27 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.458 2008/11/13 15:59:50 petere Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
@@ -8353,7 +8353,7 @@ SELECT xmlroot(xmlparse(document '<?xml version="1.1"?><content>abc</content>'),
</para>
</sect3>
- <sect3>
+ <sect3 id="functions-xml-xmlagg">
<title><literal>xmlagg</literal></title>
<indexterm>
@@ -8366,10 +8366,10 @@ SELECT xmlroot(xmlparse(document '<?xml version="1.1"?><content>abc</content>'),
<para>
The function <function>xmlagg</function> is, unlike the other
- functions below, an aggregate function. It concatenates the
+ functions described here, an aggregate function. It concatenates the
input values to the aggregate function call,
like <function>xmlconcat</function> does.
- See <xref linkend="functions-aggregate"> for general information
+ See <xref linkend="functions-aggregate"> for additional information
about aggregate functions.
</para>
@@ -8387,11 +8387,9 @@ SELECT xmlagg(x) FROM test;
</para>
<para>
- Note that in the current implementation, the order of the
- concatenation is in principle undefined. Making the input values
- to be sorted in some other way will usually work, however. For
- instance, in the above example, one could influence the order
- like so:
+ The influence the order of the concatenation, something like the
+ following approach to sort the input values can be used:
+
<screen><![CDATA[
SELECT xmlagg(x) FROM (SELECT * FROM test ORDER BY y DESC) AS tab;
xmlagg
@@ -8399,11 +8397,8 @@ SELECT xmlagg(x) FROM (SELECT * FROM test ORDER BY y DESC) AS tab;
<bar/><foo>abc</foo>
]]></screen>
- But this approach is not guaranteed to work in all situations and
- in all versions of PostgreSQL. A future version of PostgreSQL
- will probably provide an additional feature to control the order
- in a proper way (<literal>xmlagg(expr ORDER BY expr, expr,
- ...</literal>).
+ Again, see <xref linkend="functions-aggregate"> for additional
+ information.
</para>
</sect3>
@@ -9490,6 +9485,11 @@ SELECT NULLIF(value, '(none)') ...
</tbody>
</tgroup>
</table>
+
+ <para>
+ See also <xref linkend="functions-aggregate"> about the aggregate
+ function <function>array_agg</function> for use with arrays.
+ </para>
</sect1>
<sect1 id="functions-aggregate">
@@ -9526,6 +9526,22 @@ SELECT NULLIF(value, '(none)') ...
</thead>
<tbody>
+ <row>
+ <entry>
+ <indexterm>
+ <primary>array_agg</primary>
+ </indexterm>
+ <function>array_agg(<replaceable class="parameter">expression</replaceable>)</function>
+ </entry>
+ <entry>
+ any
+ </entry>
+ <entry>
+ array of the argument type
+ </entry>
+ <entry>input values concatenated into an array</entry>
+ </row>
+
<row>
<entry>
<indexterm>
@@ -9684,6 +9700,22 @@ SELECT NULLIF(value, '(none)') ...
</entry>
<entry>sum of <replaceable class="parameter">expression</replaceable> across all input values</entry>
</row>
+
+ <row>
+ <entry>
+ <indexterm>
+ <primary>xmlagg</primary>
+ </indexterm>
+ <function>xmlagg(<replaceable class="parameter">expression</replaceable>)</function>
+ </entry>
+ <entry>
+ <type>xml</type>
+ </entry>
+ <entry>
+ <type>xml</type>
+ </entry>
+ <entry>concatenation of XML values (see also <xref linkend="functions-xml-xmlagg">)</entry>
+ </row>
</tbody>
</tgroup>
</table>
@@ -9692,8 +9724,10 @@ SELECT NULLIF(value, '(none)') ...
It should be noted that except for <function>count</function>,
these functions return a null value when no rows are selected. In
particular, <function>sum</function> of no rows returns null, not
- zero as one might expect. The <function>coalesce</function> function can be
- used to substitute zero for null when necessary.
+ zero as one might expect, and <function>array_agg</function>
+ returns null rather than an empty array when there are no input
+ rows. The <function>coalesce</function> function can be used to
+ substitute zero or an empty array for null when necessary.
</para>
<note>
@@ -9733,6 +9767,25 @@ SELECT count(*) FROM sometable;
</para>
</note>
+ <para>
+ The aggregate functions <function>array_agg</function>
+ and <function>xmlagg</function>, as well as similar user-defined
+ aggregate functions, produce meaningfully different result values
+ depending on the order of the input values. In the current
+ implementation, the order of the concatenation is in principle
+ undefined. Making the input values to be sorted in some other way
+ will usually work, however. For example:
+
+<screen><![CDATA[
+SELECT xmlagg(x) FROM (SELECT * FROM test ORDER BY y DESC) AS tab;
+]]></screen>
+
+ But this approach is not guaranteed to work in all situations, and
+ it is not strictly SQL-conforming. A future version of PostgreSQL
+ might provide an additional feature to control the order in a
+ better-defined way (<literal>xmlagg(expr ORDER BY expr, expr,
+ ...</literal>).
+ </para>
<para>
<xref linkend="functions-aggregate-statistics-table"> shows
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index e28066dc687..354fd98811b 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -350,7 +350,7 @@ S094 Arrays of reference types NO
S095 Array constructors by query YES
S096 Optional array bounds YES
S097 Array element assignment NO
-S098 ARRAY_AGG NO
+S098 ARRAY_AGG NO ORDER BY clause not supported
S111 ONLY in query expressions YES
S151 Type predicate NO
S161 Subtype treatment NO
diff --git a/src/backend/utils/adt/array_userfuncs.c b/src/backend/utils/adt/array_userfuncs.c
index be2068ac5dc..4eeb64dbd81 100644
--- a/src/backend/utils/adt/array_userfuncs.c
+++ b/src/backend/utils/adt/array_userfuncs.c
@@ -6,12 +6,13 @@
* Copyright (c) 2003-2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/array_userfuncs.c,v 1.23 2008/01/01 19:45:52 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/array_userfuncs.c,v 1.24 2008/11/13 15:59:50 petere Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include "nodes/execnodes.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
@@ -465,3 +466,34 @@ create_singleton_array(FunctionCallInfo fcinfo,
return construct_md_array(dvalues, NULL, ndims, dims, lbs, element_type,
typlen, typbyval, typalign);
}
+
+Datum
+array_agg_transfn(PG_FUNCTION_ARGS)
+{
+ Oid arg1_typeid = get_fn_expr_argtype(fcinfo->flinfo, 1);
+
+ if (arg1_typeid == InvalidOid)
+ ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("could not determine input data type")));
+
+ /* cannot be called directly because of internal-type argument */
+ Assert(fcinfo->context && IsA(fcinfo->context, AggState));
+
+ PG_RETURN_POINTER(accumArrayResult(PG_ARGISNULL(0) ? NULL : (ArrayBuildState *) PG_GETARG_POINTER(0),
+ PG_ARGISNULL(1) ? (Datum) 0 : PG_GETARG_DATUM(1),
+ PG_ARGISNULL(1),
+ arg1_typeid,
+ ((AggState *) fcinfo->context)->aggcontext));
+}
+
+Datum
+array_agg_finalfn(PG_FUNCTION_ARGS)
+{
+ /* cannot be called directly because of internal-type argument */
+ Assert(fcinfo->context && IsA(fcinfo->context, AggState));
+
+ if (PG_ARGISNULL(0))
+ PG_RETURN_NULL(); /* returns null iff no input values */
+
+ PG_RETURN_ARRAYTYPE_P(makeArrayResult((ArrayBuildState *) PG_GETARG_POINTER(0), CurrentMemoryContext));
+}
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 3e7e52b57f0..1f3d9c6485c 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.504 2008/11/12 13:09:27 petere Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.505 2008/11/13 15:59:50 petere Exp $
*
*-------------------------------------------------------------------------
*/
@@ -53,6 +53,6 @@
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 200811121
+#define CATALOG_VERSION_NO 200811131
#endif
diff --git a/src/include/catalog/pg_aggregate.h b/src/include/catalog/pg_aggregate.h
index a8b4ac2f937..350f4968fcc 100644
--- a/src/include/catalog/pg_aggregate.h
+++ b/src/include/catalog/pg_aggregate.h
@@ -8,7 +8,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/pg_aggregate.h,v 1.66 2008/03/27 03:57:34 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_aggregate.h,v 1.67 2008/11/13 15:59:50 petere Exp $
*
* NOTES
* the genbki.sh script reads this file and generates .bki
@@ -220,6 +220,9 @@ DATA(insert ( 2243 bitor - 0 1560 _null_ ));
/* xml */
DATA(insert ( 2901 xmlconcat2 - 0 142 _null_ ));
+/* array */
+DATA(insert ( 2335 array_agg_transfn array_agg_finalfn 0 2281 _null_ ));
+
/*
* prototypes for functions in pg_aggregate.c
*/
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 0e83606f926..5c01d1b3701 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.526 2008/11/12 13:38:04 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.527 2008/11/13 15:59:50 petere Exp $
*
* NOTES
* The script catalog/genbki.sh reads this file and generates .bki
@@ -1022,6 +1022,13 @@ DATA(insert OID = 1193 ( array_fill PGNSP PGUID 12 1 0 0 f f f f i 2 2277 "2283
DESCR("array constructor with value");
DATA(insert OID = 1286 ( array_fill PGNSP PGUID 12 1 0 0 f f f f i 3 2277 "2283 1007 1007" _null_ _null_ _null_ array_fill_with_lower_bounds _null_ _null_ _null_ ));
DESCR("array constructor with value");
+DATA(insert OID = 2333 ( array_agg_transfn PGNSP PGUID 12 1 0 0 f f f f i 2 2281 "2281 2283" _null_ _null_ _null_ array_agg_transfn _null_ _null_ _null_ ));
+DESCR("array_agg transition function");
+DATA(insert OID = 2334 ( array_agg_finalfn PGNSP PGUID 12 1 0 0 f f f f i 1 2277 "2281" _null_ _null_ _null_ array_agg_finalfn _null_ _null_ _null_ ));
+DESCR("array_agg final function");
+DATA(insert OID = 2335 ( array_agg PGNSP PGUID 12 1 0 0 t f f f i 1 2277 "2283" _null_ _null_ _null_ aggregate_dummy _null_ _null_ _null_ ));
+DESCR("concatenate aggregate input into an array");
+
DATA(insert OID = 760 ( smgrin PGNSP PGUID 12 1 0 0 f f t f s 1 210 "2275" _null_ _null_ _null_ smgrin _null_ _null_ _null_ ));
DESCR("I/O");
DATA(insert OID = 761 ( smgrout PGNSP PGUID 12 1 0 0 f f t f s 1 2275 "210" _null_ _null_ _null_ smgrout _null_ _null_ _null_ ));
diff --git a/src/include/utils/array.h b/src/include/utils/array.h
index 33d9ad3207e..8b6ef08b276 100644
--- a/src/include/utils/array.h
+++ b/src/include/utils/array.h
@@ -49,7 +49,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/utils/array.h,v 1.70 2008/11/12 13:09:28 petere Exp $
+ * $PostgreSQL: pgsql/src/include/utils/array.h,v 1.71 2008/11/13 15:59:50 petere Exp $
*
*-------------------------------------------------------------------------
*/
@@ -275,4 +275,7 @@ extern ArrayType *create_singleton_array(FunctionCallInfo fcinfo,
Datum element,
int ndims);
+extern Datum array_agg_transfn(PG_FUNCTION_ARGS);
+extern Datum array_agg_finalfn(PG_FUNCTION_ARGS);
+
#endif /* ARRAY_H */
diff --git a/src/test/regress/expected/arrays.out b/src/test/regress/expected/arrays.out
index 804d52b7982..1e990aff732 100644
--- a/src/test/regress/expected/arrays.out
+++ b/src/test/regress/expected/arrays.out
@@ -1125,3 +1125,39 @@ select c, cardinality(c), d, cardinality(d) from arrtest;
{foo,new_word} | 2 | {bar,foo} | 2
(3 rows)
+select array_agg(unique1) from tenk1 where unique1 < 15;
+ array_agg
+--------------------------------------
+ {4,2,1,6,14,9,8,5,3,13,12,11,7,10,0}
+(1 row)
+
+select array_agg(ten) from tenk1 where unique1 < 15;
+ array_agg
+---------------------------------
+ {4,2,1,6,4,9,8,5,3,3,2,1,7,0,0}
+(1 row)
+
+select array_agg(nullif(ten, 4)) from tenk1 where unique1 < 15;
+ array_agg
+---------------------------------------
+ {NULL,2,1,6,NULL,9,8,5,3,3,2,1,7,0,0}
+(1 row)
+
+select cardinality(array_agg(unique1)) from tenk1 where unique1 < 15;
+ cardinality
+-------------
+ 15
+(1 row)
+
+select array_agg(unique1) from (select * from tenk1 order by unique1 asc) as tab where unique1 < 15;
+ array_agg
+--------------------------------------
+ {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14}
+(1 row)
+
+select array_agg(unique1) from tenk1 where unique1 < -15;
+ array_agg
+-----------
+
+(1 row)
+
diff --git a/src/test/regress/sql/arrays.sql b/src/test/regress/sql/arrays.sql
index 04b19a4acea..586f65c2dd6 100644
--- a/src/test/regress/sql/arrays.sql
+++ b/src/test/regress/sql/arrays.sql
@@ -395,3 +395,10 @@ select array_length(array[[1,2,3], [4,5,6]], 3);
select cardinality(array[1,2,3]);
select cardinality(array[[1,2,3], [4,5,6]]);
select c, cardinality(c), d, cardinality(d) from arrtest;
+
+select array_agg(unique1) from tenk1 where unique1 < 15;
+select array_agg(ten) from tenk1 where unique1 < 15;
+select array_agg(nullif(ten, 4)) from tenk1 where unique1 < 15;
+select cardinality(array_agg(unique1)) from tenk1 where unique1 < 15;
+select array_agg(unique1) from (select * from tenk1 order by unique1 asc) as tab where unique1 < 15;
+select array_agg(unique1) from tenk1 where unique1 < -15;
--
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