From: Tom Lane Date: Wed, 6 Nov 2013 18:26:34 +0000 (-0500) Subject: Support default arguments and named-argument notation for window functions. X-Git-Tag: REL9_3_2~52 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=66e6daa3e1a0c94f2fcf3463757d478c76c38b3a;p=postgresql Support default arguments and named-argument notation for window functions. These things didn't work because the planner omitted to do the necessary preprocessing of a WindowFunc's argument list. Add the few dozen lines of code needed to handle that. Although this sounds like a feature addition, it's really a bug fix because the default-argument case was likely to crash previously, due to lack of checking of the number of supplied arguments in the built-in window functions. It's not a security issue because there's no way for a non-superuser to create a window function definition with defaults that refers to a built-in C function, but nonetheless people might be annoyed that it crashes rather than producing a useful error message. So back-patch as far as the patch applies easily, which turns out to be 9.2. I'll put a band-aid in earlier versions as a separate patch. (Note that these features still don't work for aggregates, and fixing that case will be harder since we represent aggregate arg lists as target lists not bare expression lists. There's no crash risk though because CREATE AGGREGATE doesn't accept defaults, and we reject named-argument notation when parsing an aggregate call.) --- diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml index 814ae42699..d09c808a04 100644 --- a/doc/src/sgml/syntax.sgml +++ b/doc/src/sgml/syntax.sgml @@ -2501,6 +2501,14 @@ SELECT concat_lower_or_upper('Hello', 'World', uppercase := true); having numerous parameters that have default values, named or mixed notation can save a great deal of writing and reduce chances for error. + + + + 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). + + diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c index 6d5b20406e..7b11067090 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -2296,6 +2296,50 @@ eval_const_expressions_mutator(Node *node, */ return (Node *) copyObject(param); } + case T_WindowFunc: + { + WindowFunc *expr = (WindowFunc *) node; + Oid funcid = expr->winfnoid; + List *args; + 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 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->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 ae7d195a3e..edb165fcc9 100644 --- a/src/backend/parser/parse_func.c +++ b/src/backend/parser/parse_func.c @@ -497,17 +497,6 @@ ParseFuncOrColumn(ParseState *pstate, List *funcname, List *fargs, 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); diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index a7de92f306..df3d896264 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -7455,6 +7455,7 @@ get_windowfunc_expr(WindowFunc *wfunc, deparse_context *context) StringInfo buf = context->buf; Oid argtypes[FUNC_MAX_ARGS]; int nargs; + List *argnames; ListCell *l; if (list_length(wfunc->args) > FUNC_MAX_ARGS) @@ -7462,18 +7463,20 @@ get_windowfunc_expr(WindowFunc *wfunc, deparse_context *context) (errcode(ERRCODE_TOO_MANY_ARGUMENTS), errmsg("too many arguments"))); nargs = 0; + argnames = NIL; foreach(l, wfunc->args) { Node *arg = (Node *) lfirst(l); - Assert(!IsA(arg, NamedArgExpr)); + if (IsA(arg, NamedArgExpr)) + argnames = lappend(argnames, ((NamedArgExpr *) arg)->name); argtypes[nargs] = exprType(arg); nargs++; } appendStringInfo(buf, "%s(", generate_function_name(wfunc->winfnoid, nargs, - NIL, argtypes, + 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 752c7b42ff..200f1d2468 100644 --- a/src/test/regress/expected/window.out +++ b/src/test/regress/expected/window.out @@ -1022,3 +1022,38 @@ SELECT nth_value(four, 0) OVER (ORDER BY ten), ten, four FROM tenk1; ERROR: argument of nth_value must be greater than zero -- 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 769be0fdc6..a97a04c4c2 100644 --- a/src/test/regress/sql/window.sql +++ b/src/test/regress/sql/window.sql @@ -266,3 +266,13 @@ SELECT nth_value(four, 0) OVER (ORDER BY ten), ten, four FROM tenk1; -- 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;