Replace SQLValueFunction by COERCE_SQL_SYNTAX

This switch impacts 9 patterns related to a SQL-mandated special syntax
for function calls:
- LOCALTIME [ ( typmod ) ]
- LOCALTIMESTAMP [ ( typmod ) ]
- CURRENT_TIME [ ( typmod ) ]
- CURRENT_TIMESTAMP [ ( typmod ) ]
- CURRENT_DATE

Five new entries are added to pg_proc to compensate the removal of
SQLValueFunction to provide backward-compatibility and making this
change transparent for the end-user (for example for the attribute
generated when a keyword is specified in a SELECT or in a FROM clause
without an alias, or when specifying something else than an Iconst to
the parser).

The parser included a set of checks coming from the files in charge of
holding the C functions used for the SQLValueFunction calls (as of
transformSQLValueFunction()), which are now moved within each function's
execution path, so this reduces the dependencies between the execution
and the parsing steps.  As of this change, all the SQL keywords use the
same paths for their work, relying only on COERCE_SQL_SYNTAX.  Like
fb32748, no performance difference has been noticed, while the perf
profiles get reduced with ExecEvalSQLValueFunction() gone.

Bump catalog version.

Reviewed-by: Corey Huinker, Ted Yu
Discussion: https://postgr.es/m/YzaG3MoryCguUOym@paquier.xyz

1 files changed, 43 insertions, 29 deletions

diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index d8552a1f186..ef92323fd09 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -81,27 +81,6 @@ static Timestamp timestamptz2timestamp(TimestampTz timestamp);
 
 /* common code for timestamptypmodin and timestamptztypmodin */
 static int32
-anytimestamp_typmodin(bool istz, ArrayType *ta)
-{
-	int32	   *tl;
-	int			n;
-
-	tl = ArrayGetIntegerTypmods(ta, &n);
-
-	/*
-	 * we're not too tense about good error message here because grammar
-	 * shouldn't allow wrong number of modifiers for TIMESTAMP
-	 */
-	if (n != 1)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-				 errmsg("invalid type modifier")));
-
-	return anytimestamp_typmod_check(istz, tl[0]);
-}
-
-/* exported so parse_expr.c can use it */
-int32
 anytimestamp_typmod_check(bool istz, int32 typmod)
 {
 	if (typmod < 0)
@@ -122,6 +101,26 @@ anytimestamp_typmod_check(bool istz, int32 typmod)
 	return typmod;
 }
 
+static int32
+anytimestamp_typmodin(bool istz, ArrayType *ta)
+{
+	int32	   *tl;
+	int			n;
+
+	tl = ArrayGetIntegerTypmods(ta, &n);
+
+	/*
+	 * we're not too tense about good error message here because grammar
+	 * shouldn't allow wrong number of modifiers for TIMESTAMP
+	 */
+	if (n != 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("invalid type modifier")));
+
+	return anytimestamp_typmod_check(istz, tl[0]);
+}
+
 /* common code for timestamptypmodout and timestamptztypmodout */
 static char *
 anytimestamp_typmodout(bool istz, int32 typmod)
@@ -1586,33 +1585,48 @@ GetCurrentTimestamp(void)
 }
 
 /*
- * GetSQLCurrentTimestamp -- implements CURRENT_TIMESTAMP, CURRENT_TIMESTAMP(n)
+ * current_timestamp -- implements CURRENT_TIMESTAMP, CURRENT_TIMESTAMP(n)
  */
-TimestampTz
-GetSQLCurrentTimestamp(int32 typmod)
+Datum
+current_timestamp(PG_FUNCTION_ARGS)
 {
 	TimestampTz ts;
+	int32		typmod = -1;
+
+	if (!PG_ARGISNULL(0))
+	{
+		typmod = PG_GETARG_INT32(0);
+		anytimestamp_typmod_check(true, typmod);
+	}
 
 	ts = GetCurrentTransactionStartTimestamp();
 	if (typmod >= 0)
 		AdjustTimestampForTypmod(&ts, typmod);
-	return ts;
+	return TimestampTzGetDatum(ts);
 }
 
 /*
- * GetSQLLocalTimestamp -- implements LOCALTIMESTAMP, LOCALTIMESTAMP(n)
+ * sql_localtimestamp -- implements LOCALTIMESTAMP, LOCALTIMESTAMP(n)
  */
-Timestamp
-GetSQLLocalTimestamp(int32 typmod)
+Datum
+sql_localtimestamp(PG_FUNCTION_ARGS)
 {
 	Timestamp	ts;
+	int32		typmod = -1;
+
+	if (!PG_ARGISNULL(0))
+	{
+		typmod = PG_GETARG_INT32(0);
+		anytimestamp_typmod_check(false, typmod);
+	}
 
 	ts = timestamptz2timestamp(GetCurrentTransactionStartTimestamp());
 	if (typmod >= 0)
 		AdjustTimestampForTypmod(&ts, typmod);
-	return ts;
+	return TimestampGetDatum(ts);
 }
 
+
 /*
  * timeofday(*) -- returns the current time as a text.
  */