I wrote:
> Attached is a proposed patch against HEAD that fixes this by supporting
> default arguments properly for window functions. In passing, it also
> allows named-argument notation in window function calls, since that's
> free once the other thing works (because the same subroutine fixes up
> both things).
Hm, well, almost free --- turns out ruleutils.c was assuming WindowFuncs
couldn't contain named arguments. Updated patch attached.
regards, tom lane
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index e3dbc4b..16aade4 100644
*** a/doc/src/sgml/syntax.sgml
--- b/doc/src/sgml/syntax.sgml
*************** SELECT concat_lower_or_upper('Hello', 'W
*** 2527,2534 ****
<note>
<para>
! Named and mixed call notations can currently be used only with regular
! functions, not with aggregate functions or window functions.
</para>
</note>
</sect2>
--- 2527,2535 ----
<note>
<para>
! Named and mixed call notations currently cannot be used when calling an
! aggregate function (but they do work when an aggregate function is used
! as a window function).
</para>
</note>
</sect2>
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 76c032c..4fa73a9 100644
*** a/src/backend/optimizer/util/clauses.c
--- b/src/backend/optimizer/util/clauses.c
*************** eval_const_expressions_mutator(Node *nod
*** 2251,2256 ****
--- 2251,2306 ----
*/
return (Node *) copyObject(param);
}
+ case T_WindowFunc:
+ {
+ WindowFunc *expr = (WindowFunc *) node;
+ Oid funcid = expr->winfnoid;
+ List *args;
+ Expr *aggfilter;
+ HeapTuple func_tuple;
+ WindowFunc *newexpr;
+
+ /*
+ * We can't really simplify a WindowFunc node, but we mustn't
+ * just fall through to the default processing, because we
+ * have to apply expand_function_arguments to its argument
+ * list. That takes care of inserting default arguments and
+ * expanding named-argument notation.
+ */
+ func_tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
+ if (!HeapTupleIsValid(func_tuple))
+ elog(ERROR, "cache lookup failed for function %u", funcid);
+
+ args = expand_function_arguments(expr->args, expr->wintype,
+ func_tuple);
+
+ ReleaseSysCache(func_tuple);
+
+ /* Now, recursively simplify the args (which are a List) */
+ args = (List *)
+ expression_tree_mutator((Node *) args,
+ eval_const_expressions_mutator,
+ (void *) context);
+ /* ... and the filter expression, which isn't */
+ aggfilter = (Expr *)
+ eval_const_expressions_mutator((Node *) expr->aggfilter,
+ context);
+
+ /* And build the replacement WindowFunc node */
+ newexpr = makeNode(WindowFunc);
+ newexpr->winfnoid = expr->winfnoid;
+ newexpr->wintype = expr->wintype;
+ newexpr->wincollid = expr->wincollid;
+ newexpr->inputcollid = expr->inputcollid;
+ newexpr->args = args;
+ newexpr->aggfilter = aggfilter;
+ newexpr->winref = expr->winref;
+ newexpr->winstar = expr->winstar;
+ newexpr->winagg = expr->winagg;
+ newexpr->location = expr->location;
+
+ return (Node *) newexpr;
+ }
case T_FuncExpr:
{
FuncExpr *expr = (FuncExpr *) node;
diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_func.c
index 2bd24c8..ede36d1 100644
*** a/src/backend/parser/parse_func.c
--- b/src/backend/parser/parse_func.c
*************** ParseFuncOrColumn(ParseState *pstate, Li
*** 537,553 ****
errmsg("window functions cannot return sets"),
parser_errposition(pstate, location)));
- /*
- * We might want to support this later, but for now reject it because
- * the planner and executor wouldn't cope with NamedArgExprs in a
- * WindowFunc node.
- */
- if (argnames != NIL)
- ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("window functions cannot use named arguments"),
- parser_errposition(pstate, location)));
-
/* parse_agg.c does additional window-func-specific processing */
transformWindowFuncCall(pstate, wfunc, over);
--- 537,542 ----
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 04b1c4f..915fb7a 100644
*** a/src/backend/utils/adt/ruleutils.c
--- b/src/backend/utils/adt/ruleutils.c
*************** get_windowfunc_expr(WindowFunc *wfunc, d
*** 7461,7466 ****
--- 7461,7467 ----
StringInfo buf = context->buf;
Oid argtypes[FUNC_MAX_ARGS];
int nargs;
+ List *argnames;
ListCell *l;
if (list_length(wfunc->args) > FUNC_MAX_ARGS)
*************** get_windowfunc_expr(WindowFunc *wfunc, d
*** 7468,7485 ****
(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
errmsg("too many arguments")));
nargs = 0;
foreach(l, wfunc->args)
{
Node *arg = (Node *) lfirst(l);
! Assert(!IsA(arg, NamedArgExpr));
argtypes[nargs] = exprType(arg);
nargs++;
}
appendStringInfo(buf, "%s(",
generate_function_name(wfunc->winfnoid, nargs,
! NIL, argtypes,
false, NULL));
/* winstar can be set only in zero-argument aggregates */
if (wfunc->winstar)
--- 7469,7488 ----
(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
errmsg("too many arguments")));
nargs = 0;
+ argnames = NIL;
foreach(l, wfunc->args)
{
Node *arg = (Node *) lfirst(l);
! if (IsA(arg, NamedArgExpr))
! argnames = lappend(argnames, ((NamedArgExpr *) arg)->name);
argtypes[nargs] = exprType(arg);
nargs++;
}
appendStringInfo(buf, "%s(",
generate_function_name(wfunc->winfnoid, nargs,
! argnames, argtypes,
false, NULL));
/* winstar can be set only in zero-argument aggregates */
if (wfunc->winstar)
diff --git a/src/test/regress/expected/window.out b/src/test/regress/expected/window.out
index 7b31d13..1e6365b 100644
*** a/src/test/regress/expected/window.out
--- b/src/test/regress/expected/window.out
*************** FROM empsalary GROUP BY depname;
*** 1035,1037 ****
--- 1035,1072 ----
-- cleanup
DROP TABLE empsalary;
+ -- test user-defined window function with named args and default args
+ CREATE FUNCTION nth_value_def(val anyelement, n integer = 1) RETURNS anyelement
+ LANGUAGE internal WINDOW IMMUTABLE STRICT AS 'window_nth_value';
+ SELECT nth_value_def(n := 2, val := ten) OVER (PARTITION BY four), ten, four
+ FROM (SELECT * FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten) s;
+ nth_value_def | ten | four
+ ---------------+-----+------
+ 0 | 0 | 0
+ 0 | 0 | 0
+ 0 | 4 | 0
+ 1 | 1 | 1
+ 1 | 1 | 1
+ 1 | 7 | 1
+ 1 | 9 | 1
+ | 0 | 2
+ 3 | 1 | 3
+ 3 | 3 | 3
+ (10 rows)
+
+ SELECT nth_value_def(ten) OVER (PARTITION BY four), ten, four
+ FROM (SELECT * FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten) s;
+ nth_value_def | ten | four
+ ---------------+-----+------
+ 0 | 0 | 0
+ 0 | 0 | 0
+ 0 | 4 | 0
+ 1 | 1 | 1
+ 1 | 1 | 1
+ 1 | 7 | 1
+ 1 | 9 | 1
+ 0 | 0 | 2
+ 1 | 1 | 3
+ 1 | 3 | 3
+ (10 rows)
+
diff --git a/src/test/regress/sql/window.sql b/src/test/regress/sql/window.sql
index 6ee3696..7297e62 100644
*** a/src/test/regress/sql/window.sql
--- b/src/test/regress/sql/window.sql
*************** FROM empsalary GROUP BY depname;
*** 274,276 ****
--- 274,286 ----
-- cleanup
DROP TABLE empsalary;
+
+ -- test user-defined window function with named args and default args
+ CREATE FUNCTION nth_value_def(val anyelement, n integer = 1) RETURNS anyelement
+ LANGUAGE internal WINDOW IMMUTABLE STRICT AS 'window_nth_value';
+
+ SELECT nth_value_def(n := 2, val := ten) OVER (PARTITION BY four), ten, four
+ FROM (SELECT * FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten) s;
+
+ SELECT nth_value_def(ten) OVER (PARTITION BY four), ten, four
+ FROM (SELECT * FROM tenk1 WHERE unique2 < 10 ORDER BY four, ten) s;
--
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