Hi
čt 21. 2. 2019 v 22:05 odesílatel Tom Lane <t...@sss.pgh.pa.us> napsal:
> Pavel Stehule <pavel.steh...@gmail.com> writes:
> > čt 21. 2. 2019 v 3:20 odesílatel Chapman Flack <c...@anastigmatix.net>
> > napsal:
> >> I am not sure I have an answer to the objections being raised on grounds
> >> of taste. To me, it's persuasive that GREATEST and LEAST are described
> in
> >> the docco as functions, they are used much like variadic functions, and
> >> this patch allows them to be used in the ways you would expect variadic
> >> functions to be usable.
>
> > I wrote doc (just one sentence) and minimal test. Both can be enhanced.
>
> I remain of the opinion that this patch is a mess.
>
> I don't share Pavel's opinion that this is a clean user API, though
> I'll grant that others might have different opinions on that.
> I could hold my nose and overlook that if it led to a clean internal
> implementation. But it doesn't: this patch just bolts a huge,
> undocumented wart onto the side of MinMaxExpr. (The arguments are
> in the args field, except when they aren't? And everyplace that
> deals with MinMaxExpr needs to know that, as well as the fact that
> the semantics are totally different? Ick.)
>
fixed
> An example of the lack of care here is that the change in struct
> ExprEvalStep breaks that struct's size constraint:
>
> * Inline data for the operation. Inline data is faster to access, but
> * also bloats the size of all instructions. The union should be kept
> to
> * no more than 40 bytes on 64-bit systems (so that the entire struct
> is
> * no more than 64 bytes, a single cacheline on common systems).
>
>
fixed
> Andres is going to be quite displeased if that gets committed ;-).
>
I hope so I solved all your objections. Now, the patch is really reduced.
> I still say we should reject this and invent array_greatest/array_least
> functions instead.
>
I am not against these functions, but these functions doesn't solve a
confusing of some users, so LEAST, GREATEST looks like variadic functions,
but it doesn't allow VARIADIC parameter.
Comments, notes?
> regards, tom lane
>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 86ff4e5c9e..aa4e80cca7 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -12679,6 +12679,12 @@ SELECT NULLIF(value, '(none)') ...
</synopsis>
<synopsis>
<function>LEAST</function>(<replaceable>value</replaceable> <optional>, ...</optional>)
+</synopsis>
+<synopsis>
+<function>GREATEST</function>(VARIADIC <replaceable>anyarray</replaceable>)
+</synopsis>
+<synopsis>
+<function>LEAST</function>(VARIADIC <replaceable>anyarray</replaceable>)
</synopsis>
<para>
@@ -12697,6 +12703,11 @@ SELECT NULLIF(value, '(none)') ...
make them return NULL if any argument is NULL, rather than only when
all are NULL.
</para>
+
+ <para>
+ These functions supports passing parameters as a array after
+ <literal>VARIADIC</literal> keyword.
+ </para>
</sect2>
</sect1>
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index a018925d4e..418aca9c84 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -2819,6 +2819,55 @@ ExecEvalMinMax(ExprState *state, ExprEvalStep *op)
/* default to null result */
*op->resnull = true;
+ if (IsVariadicMinMax(operator))
+ {
+ ArrayIterator array_iterator;
+ ArrayType *arr;
+ Datum value;
+ bool isnull;
+
+ if (nulls[0])
+ return;
+
+ arr = DatumGetArrayTypeP(values[0]);
+
+ array_iterator = array_create_iterator(arr, 0, NULL);
+ while (array_iterate(array_iterator, &value, &isnull))
+ {
+ if (isnull)
+ continue;
+
+ if (*op->resnull)
+ {
+ /* first nonnull input */
+ *op->resvalue = value;
+ *op->resnull = false;
+ }
+ else
+ {
+ int cmpresult;
+
+ Assert(fcinfo->nargs == 2);
+
+ /* apply comparison function */
+ fcinfo->args[0].value = *op->resvalue;
+ fcinfo->args[1].value = value;
+
+ fcinfo->isnull = false;
+ cmpresult = DatumGetInt32(FunctionCallInvoke(fcinfo));
+ if (fcinfo->isnull) /* probably should not happen */
+ continue;
+
+ if (cmpresult > 0 && operator == IS_LEAST_VARIADIC)
+ *op->resvalue = value;
+ else if (cmpresult < 0 && operator == IS_GREATEST_VARIADIC)
+ *op->resvalue = value;
+ }
+ }
+
+ return;
+ }
+
for (off = 0; off < op->d.minmax.nelems; off++)
{
/* ignore NULL inputs */
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 8ed30c011a..efabaa0046 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -465,7 +465,8 @@ exprTypmod(const Node *expr)
int32 typmod;
ListCell *arg;
- if (exprType((Node *) linitial(mexpr->args)) != minmaxtype)
+ if (!IsVariadicMinMax(mexpr->op) &&
+ exprType((Node *) linitial(mexpr->args)) != minmaxtype)
return -1;
typmod = exprTypmod((Node *) linitial(mexpr->args));
if (typmod < 0)
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index a68f78e0e0..65f44a8df6 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -13803,6 +13803,22 @@ func_expr_common_subexpr:
v->location = @1;
$$ = (Node *)v;
}
+ | GREATEST '(' VARIADIC a_expr ')'
+ {
+ MinMaxExpr *v = makeNode(MinMaxExpr);
+ v->args = list_make1($4);
+ v->op = IS_GREATEST_VARIADIC;
+ v->location = @1;
+ $$ = (Node *)v;
+ }
+ | LEAST '(' VARIADIC a_expr ')'
+ {
+ MinMaxExpr *v = makeNode(MinMaxExpr);
+ v->args = list_make1($4);
+ v->op = IS_LEAST_VARIADIC;
+ v->location = @1;
+ $$ = (Node *)v;
+ }
| XMLCONCAT '(' expr_list ')'
{
$$ = makeXmlExpr(IS_XMLCONCAT, NULL, NIL, $3, @1);
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index e559353529..d739582ba0 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -2276,22 +2276,43 @@ transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m)
newargs = lappend(newargs, newe);
}
- newm->minmaxtype = select_common_type(pstate, newargs, funcname, NULL);
- /* minmaxcollid and inputcollid will be set by parse_collate.c */
+ if (IsVariadicMinMax(newm->op))
+ {
+ Oid array_typid;
+ Oid element_typid;
- /* Convert arguments if necessary */
- foreach(args, newargs)
+ array_typid = exprType(linitial(newargs));
+
+ if (array_typid == InvalidOid)
+ elog(ERROR, "cannot to determinate result type");
+
+ element_typid = get_base_element_type(array_typid);
+ if (!OidIsValid(element_typid))
+ elog(ERROR, "expected a array parameter");
+
+ newm->minmaxtype = element_typid;
+ newm->args = newargs;
+ }
+ else
{
- Node *e = (Node *) lfirst(args);
- Node *newe;
+ newm->minmaxtype = select_common_type(pstate, newargs, funcname, NULL);
+ /* minmaxcollid and inputcollid will be set by parse_collate.c */
- newe = coerce_to_common_type(pstate, e,
- newm->minmaxtype,
- funcname);
- newcoercedargs = lappend(newcoercedargs, newe);
+ /* Convert arguments if necessary */
+ foreach(args, newargs)
+ {
+ Node *e = (Node *) lfirst(args);
+ Node *newe;
+
+ newe = coerce_to_common_type(pstate, e,
+ newm->minmaxtype,
+ funcname);
+ newcoercedargs = lappend(newcoercedargs, newe);
+ }
+
+ newm->args = newcoercedargs;
}
- newm->args = newcoercedargs;
newm->location = m->location;
return (Node *) newm;
}
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 0e9598ebfe..013596756d 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -1843,9 +1843,11 @@ FigureColnameInternal(Node *node, char **name)
switch (((MinMaxExpr *) node)->op)
{
case IS_GREATEST:
+ case IS_GREATEST_VARIADIC:
*name = "greatest";
return 2;
case IS_LEAST:
+ case IS_LEAST_VARIADIC:
*name = "least";
return 2;
}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 1258092dc8..6e7ebb1861 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -8468,13 +8468,23 @@ get_rule_expr(Node *node, deparse_context *context,
switch (minmaxexpr->op)
{
case IS_GREATEST:
+ case IS_GREATEST_VARIADIC:
appendStringInfoString(buf, "GREATEST(");
break;
case IS_LEAST:
+ case IS_LEAST_VARIADIC:
appendStringInfoString(buf, "LEAST(");
break;
}
- get_rule_expr((Node *) minmaxexpr->args, context, true);
+
+ if (IsVariadicMinMax(minmaxexpr->op))
+ {
+ appendStringInfoString(buf, "VARIADIC ");
+ get_rule_expr(linitial(minmaxexpr->args), context, true);
+ }
+ else
+ get_rule_expr((Node *) minmaxexpr->args, context, true);
+
appendStringInfoChar(buf, ')');
}
break;
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index a7efae7038..827fcf6d42 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -1080,9 +1080,14 @@ typedef struct CoalesceExpr
typedef enum MinMaxOp
{
IS_GREATEST,
- IS_LEAST
+ IS_LEAST,
+ IS_GREATEST_VARIADIC,
+ IS_LEAST_VARIADIC
} MinMaxOp;
+#define IsVariadicMinMax(op) (op == IS_GREATEST_VARIADIC || \
+ op == IS_LEAST_VARIADIC)
+
typedef struct MinMaxExpr
{
Expr xpr;
diff --git a/src/test/regress/expected/case.out b/src/test/regress/expected/case.out
index c0c8acf035..eca127ed2d 100644
--- a/src/test/regress/expected/case.out
+++ b/src/test/regress/expected/case.out
@@ -392,3 +392,54 @@ ROLLBACK;
--
DROP TABLE CASE_TBL;
DROP TABLE CASE2_TBL;
+--
+-- greatest and least tests
+--
+SELECT least(10,20,30,40);
+ least
+-------
+ 10
+(1 row)
+
+SELECT greatest(10,20,30,40);
+ greatest
+----------
+ 40
+(1 row)
+
+SELECT least(VARIADIC ARRAY[10,20,30,40]);
+ least
+-------
+ 10
+(1 row)
+
+SELECT greatest(VARIADIC ARRAY[10,20,30,40]);
+ greatest
+----------
+ 40
+(1 row)
+
+SELECT least(10,20,30,40, NULL);
+ least
+-------
+ 10
+(1 row)
+
+SELECT greatest(10,20,30,40, NULL);
+ greatest
+----------
+ 40
+(1 row)
+
+SELECT least(VARIADIC ARRAY[10,20,30,40, NULL]);
+ least
+-------
+ 10
+(1 row)
+
+SELECT greatest(VARIADIC ARRAY[10,20,30,40, NULL]);
+ greatest
+----------
+ 40
+(1 row)
+
diff --git a/src/test/regress/sql/case.sql b/src/test/regress/sql/case.sql
index 17436c524a..c482676e17 100644
--- a/src/test/regress/sql/case.sql
+++ b/src/test/regress/sql/case.sql
@@ -252,3 +252,16 @@ ROLLBACK;
DROP TABLE CASE_TBL;
DROP TABLE CASE2_TBL;
+
+--
+-- greatest and least tests
+--
+SELECT least(10,20,30,40);
+SELECT greatest(10,20,30,40);
+SELECT least(VARIADIC ARRAY[10,20,30,40]);
+SELECT greatest(VARIADIC ARRAY[10,20,30,40]);
+
+SELECT least(10,20,30,40, NULL);
+SELECT greatest(10,20,30,40, NULL);
+SELECT least(VARIADIC ARRAY[10,20,30,40, NULL]);
+SELECT greatest(VARIADIC ARRAY[10,20,30,40, NULL]);
