Improve parsetree representation of special functions such as CURRENT_DATE.

We implement a dozen or so parameterless functions that the SQL standard
defines special syntax for.  Up to now, that was done by converting them
into more or less ad-hoc constructs such as "'now'::text::date".  That's
messy for multiple reasons: it exposes what should be implementation
details to users, and performance is worse than it needs to be in several
cases.  To improve matters, invent a new expression node type
SQLValueFunction that can represent any of these parameterless functions.

Bump catversion because this changes stored parsetrees for rules.

Discussion: <30058.1463091294@sss.pgh.pa.us>

1 files changed, 14 insertions, 0 deletions

diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index acaf4ea5ebc..1fab807772c 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -1424,6 +1424,17 @@ _outMinMaxExpr(StringInfo str, const MinMaxExpr *node)
 }
 
 static void
+_outSQLValueFunction(StringInfo str, const SQLValueFunction *node)
+{
+	WRITE_NODE_TYPE("SQLVALUEFUNCTION");
+
+	WRITE_ENUM_FIELD(op, SQLValueFunctionOp);
+	WRITE_OID_FIELD(type);
+	WRITE_INT_FIELD(typmod);
+	WRITE_LOCATION_FIELD(location);
+}
+
+static void
 _outXmlExpr(StringInfo str, const XmlExpr *node)
 {
 	WRITE_NODE_TYPE("XMLEXPR");
@@ -3522,6 +3533,9 @@ outNode(StringInfo str, const void *obj)
 			case T_MinMaxExpr:
 				_outMinMaxExpr(str, obj);
 				break;
+			case T_SQLValueFunction:
+				_outSQLValueFunction(str, obj);
+				break;
 			case T_XmlExpr:
 				_outXmlExpr(str, obj);
 				break;