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Add Oracle-compatible GREATEST and LEAST functions. Pavel Stehule
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17 files changed

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-36
lines changed

17 files changed

+409
-36
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‎doc/src/sgml/func.sgml

Lines changed: 34 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.259 2005/06/24 20:53:29 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.260 2005/06/26 22:05:35 tgl Exp $
33
PostgreSQL documentation
44
-->
55

@@ -6901,6 +6901,39 @@ SELECT NULLIF(value, '(none)') ...
69016901

69026902
</sect2>
69036903

6904+
<sect2>
6905+
<title><literal>GREATEST</literal> and <literal>LEAST</literal></title>
6906+
6907+
<indexterm>
6908+
<primary>GREATEST</primary>
6909+
</indexterm>
6910+
<indexterm>
6911+
<primary>LEAST</primary>
6912+
</indexterm>
6913+
6914+
<synopsis>
6915+
<function>GREATEST</function>(<replaceable>value</replaceable> <optional>, ...</optional>)
6916+
</synopsis>
6917+
<synopsis>
6918+
<function>LEAST</function>(<replaceable>value</replaceable> <optional>, ...</optional>)
6919+
</synopsis>
6920+
6921+
<para>
6922+
The <function>GREATEST</> and <function>LEAST</> functions select the
6923+
largest or smallest value from a list of any number of expressions.
6924+
The expressions must all be convertible to a common data type, which
6925+
will be the type of the result
6926+
(see <xref linkend="typeconv-union-case"> for details). NULL values
6927+
in the list are ignored. The result will be NULL only if all the
6928+
expressions evaluate to NULL.
6929+
</para>
6930+
6931+
<para>
6932+
Note that <function>GREATEST</> and <function>LEAST</> are not in
6933+
the SQL standard, but are a common extension.
6934+
</para>
6935+
</sect2>
6936+
69046937
</sect1>
69056938

69066939

‎doc/src/sgml/typeconv.sgml

Lines changed: 19 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/typeconv.sgml,v 1.43 2004/12/23 23:07:38 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/typeconv.sgml,v 1.44 2005/06/26 22:05:36 tgl Exp $
33
-->
44

55
<chapter Id="typeconv">
@@ -120,7 +120,7 @@ with, and perhaps converted to, the types of the target columns.
120120
</varlistentry>
121121
<varlistentry>
122122
<term>
123-
<literal>UNION</literal>, <literal>CASE</literal>, and <literal>ARRAY</literal> constructs
123+
<literal>UNION</literal>, <literal>CASE</literal>, and related constructs
124124
</term>
125125
<listitem>
126126
<para>
@@ -129,7 +129,8 @@ must appear in a single set of columns, the types of the results of each
129129
<command>SELECT</> clause must be matched up and converted to a uniform set.
130130
Similarly, the result expressions of a <literal>CASE</> construct must be
131131
converted to a common type so that the <literal>CASE</> expression as a whole
132-
has a known output type. The same holds for <literal>ARRAY</> constructs.
132+
has a known output type. The same holds for <literal>ARRAY</> constructs,
133+
and for the <function>GREATEST</> and <function>LEAST</> functions.
133134
</para>
134135
</listitem>
135136
</varlistentry>
@@ -782,7 +783,7 @@ padding spaces.
782783
</sect1>
783784

784785
<sect1 id="typeconv-union-case">
785-
<title><literal>UNION</literal>, <literal>CASE</literal>, and <literal>ARRAY</literal> Constructs</title>
786+
<title><literal>UNION</literal>, <literal>CASE</literal>, and Related Constructs</title>
786787

787788
<indexterm zone="typeconv-union-case">
788789
<primary>UNION</primary>
@@ -799,20 +800,31 @@ padding spaces.
799800
<secondary>determination of result type</secondary>
800801
</indexterm>
801802

803+
<indexterm zone="typeconv-union-case">
804+
<primary>GREATEST</primary>
805+
<secondary>determination of result type</secondary>
806+
</indexterm>
807+
808+
<indexterm zone="typeconv-union-case">
809+
<primary>LEAST</primary>
810+
<secondary>determination of result type</secondary>
811+
</indexterm>
812+
802813
<para>
803814
SQL <literal>UNION</> constructs must match up possibly dissimilar
804815
types to become a single result set. The resolution algorithm is
805816
applied separately to each output column of a union query. The
806817
<literal>INTERSECT</> and <literal>EXCEPT</> constructs resolve
807818
dissimilar types in the same way as <literal>UNION</>. The
808-
<literal>CASE</> and <literal>ARRAY</> constructs use the identical
819+
<literal>CASE</>, <literal>ARRAY</>, <function>GREATEST</> and
820+
<function>LEAST</> constructs use the identical
809821
algorithm to match up their component expressions and select a result
810822
data type.
811823
</para>
812824

813825
<procedure>
814-
<title><literal>UNION</literal>, <literal>CASE</literal>, and
815-
<literal>ARRAY</literal> Type Resolution</title>
826+
<title>Type Resolution for <literal>UNION</literal>, <literal>CASE</literal>,
827+
and Related Constructs</title>
816828

817829
<step performance="required">
818830
<para>

‎src/backend/executor/execQual.c

Lines changed: 91 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.179 2005/05/12 20:41:56 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.180 2005/06/26 22:05:36 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -105,6 +105,9 @@ static Datum ExecEvalRow(RowExprState *rstate,
105105
static Datum ExecEvalCoalesce(CoalesceExprState *coalesceExpr,
106106
ExprContext *econtext,
107107
bool *isNull, ExprDoneCond *isDone);
108+
static Datum ExecEvalMinMax(MinMaxExprState *minmaxExpr,
109+
ExprContext *econtext,
110+
bool *isNull, ExprDoneCond *isDone);
108111
static Datum ExecEvalNullIf(FuncExprState *nullIfExpr,
109112
ExprContext *econtext,
110113
bool *isNull, ExprDoneCond *isDone);
@@ -2247,6 +2250,63 @@ ExecEvalCoalesce(CoalesceExprState *coalesceExpr, ExprContext *econtext,
22472250
return (Datum) 0;
22482251
}
22492252

2253+
/* ----------------------------------------------------------------
2254+
* ExecEvalMinMax
2255+
* ----------------------------------------------------------------
2256+
*/
2257+
static Datum
2258+
ExecEvalMinMax(MinMaxExprState *minmaxExpr, ExprContext *econtext,
2259+
bool *isNull, ExprDoneCond *isDone)
2260+
{
2261+
Datum result = (Datum) 0;
2262+
MinMaxOp op = ((MinMaxExpr *) minmaxExpr->xprstate.expr)->op;
2263+
FunctionCallInfoData locfcinfo;
2264+
ListCell *arg;
2265+
2266+
if (isDone)
2267+
*isDone = ExprSingleResult;
2268+
*isNull = true; /* until we get a result */
2269+
2270+
InitFunctionCallInfoData(locfcinfo, &minmaxExpr->cfunc, 2, NULL, NULL);
2271+
locfcinfo.argnull[0] = false;
2272+
locfcinfo.argnull[1] = false;
2273+
2274+
foreach(arg, minmaxExpr->args)
2275+
{
2276+
ExprState *e = (ExprState *) lfirst(arg);
2277+
Datum value;
2278+
bool valueIsNull;
2279+
int32 cmpresult;
2280+
2281+
value = ExecEvalExpr(e, econtext, &valueIsNull, NULL);
2282+
if (valueIsNull)
2283+
continue; /* ignore NULL inputs */
2284+
2285+
if (*isNull)
2286+
{
2287+
/* first nonnull input, adopt value */
2288+
result = value;
2289+
*isNull = false;
2290+
}
2291+
else
2292+
{
2293+
/* apply comparison function */
2294+
locfcinfo.arg[0] = result;
2295+
locfcinfo.arg[1] = value;
2296+
locfcinfo.isnull = false;
2297+
cmpresult = DatumGetInt32(FunctionCallInvoke(&locfcinfo));
2298+
if (locfcinfo.isnull) /* probably should not happen */
2299+
continue;
2300+
if (cmpresult > 0 && op == IS_LEAST)
2301+
result = value;
2302+
else if (cmpresult < 0 && op == IS_GREATEST)
2303+
result = value;
2304+
}
2305+
}
2306+
2307+
return result;
2308+
}
2309+
22502310
/* ----------------------------------------------------------------
22512311
* ExecEvalNullIf
22522312
*
@@ -3206,6 +3266,36 @@ ExecInitExpr(Expr *node, PlanState *parent)
32063266
state = (ExprState *) cstate;
32073267
}
32083268
break;
3269+
case T_MinMaxExpr:
3270+
{
3271+
MinMaxExpr *minmaxexpr = (MinMaxExpr *) node;
3272+
MinMaxExprState *mstate = makeNode(MinMaxExprState);
3273+
List *outlist = NIL;
3274+
ListCell *l;
3275+
TypeCacheEntry *typentry;
3276+
3277+
mstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalMinMax;
3278+
foreach(l, minmaxexpr->args)
3279+
{
3280+
Expr *e = (Expr *) lfirst(l);
3281+
ExprState *estate;
3282+
3283+
estate = ExecInitExpr(e, parent);
3284+
outlist = lappend(outlist, estate);
3285+
}
3286+
mstate->args = outlist;
3287+
/* Look up the btree comparison function for the datatype */
3288+
typentry = lookup_type_cache(minmaxexpr->minmaxtype,
3289+
TYPECACHE_CMP_PROC);
3290+
if (!OidIsValid(typentry->cmp_proc))
3291+
ereport(ERROR,
3292+
(errcode(ERRCODE_UNDEFINED_FUNCTION),
3293+
errmsg("could not identify a comparison function for type %s",
3294+
format_type_be(minmaxexpr->minmaxtype))));
3295+
fmgr_info(typentry->cmp_proc, &(mstate->cfunc));
3296+
state = (ExprState *) mstate;
3297+
}
3298+
break;
32093299
case T_NullIfExpr:
32103300
{
32113301
NullIfExpr *nullifexpr = (NullIfExpr *) node;

‎src/backend/nodes/copyfuncs.c

Lines changed: 19 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,7 @@
1515
* Portions Copyright (c) 1994, Regents of the University of California
1616
*
1717
* IDENTIFICATION
18-
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.308 2005/06/22 21:14:29 tgl Exp $
18+
* $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.309 2005/06/26 22:05:37 tgl Exp $
1919
*
2020
*-------------------------------------------------------------------------
2121
*/
@@ -1047,6 +1047,21 @@ _copyCoalesceExpr(CoalesceExpr *from)
10471047
return newnode;
10481048
}
10491049

1050+
/*
1051+
* _copyMinMaxExpr
1052+
*/
1053+
static MinMaxExpr *
1054+
_copyMinMaxExpr(MinMaxExpr *from)
1055+
{
1056+
MinMaxExpr *newnode = makeNode(MinMaxExpr);
1057+
1058+
COPY_SCALAR_FIELD(minmaxtype);
1059+
COPY_SCALAR_FIELD(op);
1060+
COPY_NODE_FIELD(args);
1061+
1062+
return newnode;
1063+
}
1064+
10501065
/*
10511066
* _copyNullIfExpr (same as OpExpr)
10521067
*/
@@ -2805,6 +2820,9 @@ copyObject(void *from)
28052820
case T_CoalesceExpr:
28062821
retval = _copyCoalesceExpr(from);
28072822
break;
2823+
case T_MinMaxExpr:
2824+
retval = _copyMinMaxExpr(from);
2825+
break;
28082826
case T_NullIfExpr:
28092827
retval = _copyNullIfExpr(from);
28102828
break;

‎src/backend/nodes/equalfuncs.c

Lines changed: 14 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -18,7 +18,7 @@
1818
* Portions Copyright (c) 1994, Regents of the University of California
1919
*
2020
* IDENTIFICATION
21-
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.245 2005/06/22 21:14:29 tgl Exp $
21+
* $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.246 2005/06/26 22:05:37 tgl Exp $
2222
*
2323
*-------------------------------------------------------------------------
2424
*/
@@ -450,6 +450,16 @@ _equalCoalesceExpr(CoalesceExpr *a, CoalesceExpr *b)
450450
return true;
451451
}
452452

453+
static bool
454+
_equalMinMaxExpr(MinMaxExpr *a, MinMaxExpr *b)
455+
{
456+
COMPARE_SCALAR_FIELD(minmaxtype);
457+
COMPARE_SCALAR_FIELD(op);
458+
COMPARE_NODE_FIELD(args);
459+
460+
return true;
461+
}
462+
453463
static bool
454464
_equalNullIfExpr(NullIfExpr *a, NullIfExpr *b)
455465
{
@@ -1868,6 +1878,9 @@ equal(void *a, void *b)
18681878
case T_CoalesceExpr:
18691879
retval = _equalCoalesceExpr(a, b);
18701880
break;
1881+
case T_MinMaxExpr:
1882+
retval = _equalMinMaxExpr(a, b);
1883+
break;
18711884
case T_NullIfExpr:
18721885
retval = _equalNullIfExpr(a, b);
18731886
break;

‎src/backend/nodes/outfuncs.c

Lines changed: 14 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.255 2005/06/09 04:18:58 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.256 2005/06/26 22:05:37 tgl Exp $
1212
*
1313
* NOTES
1414
* Every node type that can appear in stored rules' parsetrees *must*
@@ -864,6 +864,16 @@ _outCoalesceExpr(StringInfo str, CoalesceExpr *node)
864864
WRITE_NODE_FIELD(args);
865865
}
866866

867+
static void
868+
_outMinMaxExpr(StringInfo str, MinMaxExpr *node)
869+
{
870+
WRITE_NODE_TYPE("MINMAX");
871+
872+
WRITE_OID_FIELD(minmaxtype);
873+
WRITE_ENUM_FIELD(op, MinMaxOp);
874+
WRITE_NODE_FIELD(args);
875+
}
876+
867877
static void
868878
_outNullIfExpr(StringInfo str, NullIfExpr *node)
869879
{
@@ -1896,6 +1906,9 @@ _outNode(StringInfo str, void *obj)
18961906
case T_CoalesceExpr:
18971907
_outCoalesceExpr(str, obj);
18981908
break;
1909+
case T_MinMaxExpr:
1910+
_outMinMaxExpr(str, obj);
1911+
break;
18991912
case T_NullIfExpr:
19001913
_outNullIfExpr(str, obj);
19011914
break;

‎src/backend/nodes/readfuncs.c

Lines changed: 18 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.178 2005/06/05 22:32:54 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.179 2005/06/26 22:05:37 tgl Exp $
1212
*
1313
* NOTES
1414
* Path and Plan nodes do not have any readfuncs support, because we
@@ -658,6 +658,21 @@ _readCoalesceExpr(void)
658658
READ_DONE();
659659
}
660660

661+
/*
662+
* _readMinMaxExpr
663+
*/
664+
static MinMaxExpr *
665+
_readMinMaxExpr(void)
666+
{
667+
READ_LOCALS(MinMaxExpr);
668+
669+
READ_OID_FIELD(minmaxtype);
670+
READ_ENUM_FIELD(op, MinMaxOp);
671+
READ_NODE_FIELD(args);
672+
673+
READ_DONE();
674+
}
675+
661676
/*
662677
* _readNullIfExpr
663678
*/
@@ -982,6 +997,8 @@ parseNodeString(void)
982997
return_value = _readRowExpr();
983998
else if (MATCH("COALESCE", 8))
984999
return_value = _readCoalesceExpr();
1000+
else if (MATCH("MINMAX", 6))
1001+
return_value = _readMinMaxExpr();
9851002
else if (MATCH("NULLIFEXPR", 10))
9861003
return_value = _readNullIfExpr();
9871004
else if (MATCH("NULLTEST", 8))

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