Add string_agg aggregate functions. The one argument version concatenates
the input values into a string. The two argument version also does the same thing, but inserts delimiters between elements. Original patch by Pavel Stehule, reviewed by David E. Wheeler and me.
This commit is contained in:
Itagaki Takahiro
parent
ee3a81f0a0
commit
9ea9918e37
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@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.498 2010/01/25 20:55:32 tgl Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.499 2010/02/01 03:14:43 itagaki Exp $ -->
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<chapter id="functions">
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<title>Functions and Operators</title>
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@ -1789,6 +1789,10 @@
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</tgroup>
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</table>
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<para>
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See also <xref linkend="functions-aggregate"> about the aggregate
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function <function>string_agg</function>.
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</para>
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<table id="conversion-names">
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<title>Built-in Conversions</title>
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@ -9836,6 +9840,25 @@ SELECT NULLIF(value, '(none)') ...
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</entry>
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</row>
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<row>
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<entry>
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<indexterm>
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<primary>string_agg</primary>
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</indexterm>
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<function>
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string_agg(<replaceable class="parameter">expression</replaceable>
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[, <replaceable class="parameter">delimiter</replaceable> ] )
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</function>
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</entry>
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<entry>
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<type>text</type>
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</entry>
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<entry>
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<type>text</type>
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</entry>
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<entry>input values concatenated into a string, optionally with delimiters</entry>
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</row>
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<row>
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<entry><function>sum(<replaceable class="parameter">expression</replaceable>)</function></entry>
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<entry>
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.174 2010/01/25 20:55:32 tgl Exp $
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* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.175 2010/02/01 03:14:43 itagaki Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -21,6 +21,7 @@
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#include "libpq/md5.h"
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#include "libpq/pqformat.h"
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#include "miscadmin.h"
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#include "nodes/execnodes.h"
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#include "parser/scansup.h"
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#include "regex/regex.h"
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#include "utils/builtins.h"
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@ -73,6 +74,7 @@ static bytea *bytea_substring(Datum str,
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int L,
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bool length_not_specified);
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static bytea *bytea_overlay(bytea *t1, bytea *t2, int sp, int sl);
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static StringInfo makeStringAggState(fmNodePtr context);
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/*****************************************************************************
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@ -3315,3 +3317,105 @@ pg_column_size(PG_FUNCTION_ARGS)
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PG_RETURN_INT32(result);
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}
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/*
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* string_agg - Concatenates values and returns string.
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*
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* Syntax: string_agg(value text, delimiter text = '') RETURNS text
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*
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* Note: Any NULL values are ignored. The first-call delimiter isn't
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* actually used at all, and on subsequent calls the delimiter precedes
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* the associated value.
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*/
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static StringInfo
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makeStringAggState(fmNodePtr context)
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{
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StringInfo state;
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MemoryContext aggcontext;
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MemoryContext oldcontext;
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if (context && IsA(context, AggState))
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aggcontext = ((AggState *) context)->aggcontext;
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else if (context && IsA(context, WindowAggState))
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aggcontext = ((WindowAggState *) context)->wincontext;
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else
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{
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/* cannot be called directly because of internal-type argument */
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elog(ERROR, "string_agg_transfn called in non-aggregate context");
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aggcontext = NULL; /* keep compiler quiet */
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}
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/* Create state in aggregate context */
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oldcontext = MemoryContextSwitchTo(aggcontext);
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state = makeStringInfo();
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MemoryContextSwitchTo(oldcontext);
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return state;
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}
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Datum
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string_agg_transfn(PG_FUNCTION_ARGS)
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{
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StringInfo state;
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state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);
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/* Append the element unless not null. */
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if (!PG_ARGISNULL(1))
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{
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if (state == NULL)
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state = makeStringAggState(fcinfo->context);
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appendStringInfoText(state, PG_GETARG_TEXT_PP(1)); /* value */
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}
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/*
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* The transition type for string_agg() is declared to be "internal", which
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* is a pass-by-value type the same size as a pointer.
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*/
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PG_RETURN_POINTER(state);
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}
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Datum
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string_agg_delim_transfn(PG_FUNCTION_ARGS)
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{
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StringInfo state;
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state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);
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/* Append the value unless not null. */
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if (!PG_ARGISNULL(1))
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{
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if (state == NULL)
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state = makeStringAggState(fcinfo->context);
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else if (!PG_ARGISNULL(2))
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appendStringInfoText(state, PG_GETARG_TEXT_PP(2)); /* delimiter */
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appendStringInfoText(state, PG_GETARG_TEXT_PP(1)); /* value */
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}
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/*
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* The transition type for string_agg() is declared to be "internal", which
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* is a pass-by-value type the same size as a pointer.
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*/
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PG_RETURN_POINTER(state);
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}
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Datum
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string_agg_finalfn(PG_FUNCTION_ARGS)
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{
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StringInfo state;
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if (PG_ARGISNULL(0))
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PG_RETURN_NULL();
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/* cannot be called directly because of internal-type argument */
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Assert(fcinfo->context &&
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(IsA(fcinfo->context, AggState) ||
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IsA(fcinfo->context, WindowAggState)));
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state = (StringInfo) PG_GETARG_POINTER(0);
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if (state != NULL)
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PG_RETURN_TEXT_P(cstring_to_text(state->data));
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else
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PG_RETURN_NULL();
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}
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@ -37,7 +37,7 @@
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.581 2010/01/28 23:21:12 petere Exp $
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* $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.582 2010/02/01 03:14:43 itagaki Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -53,6 +53,6 @@
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*/
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/* yyyymmddN */
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#define CATALOG_VERSION_NO 201001282
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#define CATALOG_VERSION_NO 201002011
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#endif
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/catalog/pg_aggregate.h,v 1.70 2010/01/05 01:06:56 tgl Exp $
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* $PostgreSQL: pgsql/src/include/catalog/pg_aggregate.h,v 1.71 2010/02/01 03:14:43 itagaki Exp $
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*
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* NOTES
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* the genbki.pl script reads this file and generates .bki
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@ -223,6 +223,10 @@ DATA(insert ( 2901 xmlconcat2 - 0 142 _null_ ));
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/* array */
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DATA(insert ( 2335 array_agg_transfn array_agg_finalfn 0 2281 _null_ ));
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/* text */
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DATA(insert (3537 string_agg_transfn string_agg_finalfn 0 2281 _null_ ));
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DATA(insert (3538 string_agg_delim_transfn string_agg_finalfn 0 2281 _null_ ));
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/*
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* prototypes for functions in pg_aggregate.c
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*/
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.566 2010/01/28 14:25:41 mha Exp $
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* $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.567 2010/02/01 03:14:44 itagaki Exp $
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*
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* NOTES
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* The script catalog/genbki.pl reads this file and generates .bki
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@ -2829,6 +2829,16 @@ DATA(insert OID = 2816 ( float8_covar_samp PGNSP PGUID 12 1 0 0 f f f t f i 1
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DESCR("COVAR_SAMP(double, double) aggregate final function");
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DATA(insert OID = 2817 ( float8_corr PGNSP PGUID 12 1 0 0 f f f t f i 1 0 701 "1022" _null_ _null_ _null_ _null_ float8_corr _null_ _null_ _null_ ));
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DESCR("CORR(double, double) aggregate final function");
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DATA(insert OID = 3534 ( string_agg_transfn PGNSP PGUID 12 1 0 0 f f f f f i 2 0 2281 "2281 25" _null_ _null_ _null_ _null_ string_agg_transfn _null_ _null_ _null_ ));
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DESCR("string_agg(text) transition function");
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DATA(insert OID = 3535 ( string_agg_delim_transfn PGNSP PGUID 12 1 0 0 f f f f f i 3 0 2281 "2281 25 25" _null_ _null_ _null_ _null_ string_agg_delim_transfn _null_ _null_ _null_ ));
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DESCR("string_agg(text, text) transition function");
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DATA(insert OID = 3536 ( string_agg_finalfn PGNSP PGUID 12 1 0 0 f f f f f i 1 0 25 "2281" _null_ _null_ _null_ _null_ string_agg_finalfn _null_ _null_ _null_ ));
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DESCR("string_agg final function");
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DATA(insert OID = 3537 ( string_agg PGNSP PGUID 12 1 0 0 t f f f f i 1 0 25 "25" _null_ _null_ _null_ _null_ aggregate_dummy _null_ _null_ _null_ ));
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DESCR("concatenate aggregate input into an string");
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DATA(insert OID = 3538 ( string_agg PGNSP PGUID 12 1 0 0 t f f f f i 2 0 25 "25 25" _null_ _null_ _null_ _null_ aggregate_dummy _null_ _null_ _null_ ));
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DESCR("concatenate aggregate input into an string with delimiter");
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/* To ASCII conversion */
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DATA(insert OID = 1845 ( to_ascii PGNSP PGUID 12 1 0 0 f f f t f i 1 0 25 "25" _null_ _null_ _null_ _null_ to_ascii_default _null_ _null_ _null_ ));
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.345 2010/01/25 20:55:32 tgl Exp $
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* $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.346 2010/02/01 03:14:45 itagaki Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -724,6 +724,10 @@ extern Datum unknownsend(PG_FUNCTION_ARGS);
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extern Datum pg_column_size(PG_FUNCTION_ARGS);
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extern Datum string_agg_transfn(PG_FUNCTION_ARGS);
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extern Datum string_agg_delim_transfn(PG_FUNCTION_ARGS);
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extern Datum string_agg_finalfn(PG_FUNCTION_ARGS);
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/* version.c */
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extern Datum pgsql_version(PG_FUNCTION_ARGS);
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@ -772,6 +776,9 @@ extern Datum translate(PG_FUNCTION_ARGS);
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extern Datum chr (PG_FUNCTION_ARGS);
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extern Datum repeat(PG_FUNCTION_ARGS);
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extern Datum ascii(PG_FUNCTION_ARGS);
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extern Datum string_agg_transfn(PG_FUNCTION_ARGS);
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extern Datum string_agg_delim_transfn(PG_FUNCTION_ARGS);
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extern Datum string_agg_finalfn(PG_FUNCTION_ARGS);
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/* inet_net_ntop.c */
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extern char *inet_net_ntop(int af, const void *src, int bits,
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@ -799,3 +799,34 @@ select aggfns(distinct a,a,c order by a,b)
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ERROR: in an aggregate with DISTINCT, ORDER BY expressions must appear in argument list
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LINE 1: select aggfns(distinct a,a,c order by a,b)
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^
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-- string_agg tests
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select string_agg(a) from (values('aaaa'),('bbbb'),('cccc')) g(a);
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string_agg
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--------------
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aaaabbbbcccc
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(1 row)
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select string_agg(a,',') from (values('aaaa'),('bbbb'),('cccc')) g(a);
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string_agg
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----------------
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aaaa,bbbb,cccc
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(1 row)
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select string_agg(a,',') from (values('aaaa'),(null),('bbbb'),('cccc')) g(a);
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string_agg
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----------------
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aaaa,bbbb,cccc
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(1 row)
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select string_agg(a,',') from (values(null),(null),('bbbb'),('cccc')) g(a);
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string_agg
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------------
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bbbb,cccc
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(1 row)
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select string_agg(a,',') from (values(null),(null)) g(a);
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string_agg
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------------
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(1 row)
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@ -355,3 +355,10 @@ select aggfns(distinct a,b,c order by a,b,i,c)
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from (values (1,1,'foo')) v(a,b,c), generate_series(1,2) i;
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select aggfns(distinct a,a,c order by a,b)
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from (values (1,1,'foo')) v(a,b,c), generate_series(1,2) i;
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-- string_agg tests
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select string_agg(a) from (values('aaaa'),('bbbb'),('cccc')) g(a);
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select string_agg(a,',') from (values('aaaa'),('bbbb'),('cccc')) g(a);
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select string_agg(a,',') from (values('aaaa'),(null),('bbbb'),('cccc')) g(a);
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select string_agg(a,',') from (values(null),(null),('bbbb'),('cccc')) g(a);
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select string_agg(a,',') from (values(null),(null)) g(a);
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