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, 19 insertions, 0 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 3244c76ddcc..c7a06442ba6 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1753,6 +1753,22 @@ _copyMinMaxExpr(const MinMaxExpr *from)
 }
 
 /*
+ * _copySQLValueFunction
+ */
+static SQLValueFunction *
+_copySQLValueFunction(const SQLValueFunction *from)
+{
+	SQLValueFunction *newnode = makeNode(SQLValueFunction);
+
+	COPY_SCALAR_FIELD(op);
+	COPY_SCALAR_FIELD(type);
+	COPY_SCALAR_FIELD(typmod);
+	COPY_LOCATION_FIELD(location);
+
+	return newnode;
+}
+
+/*
  * _copyXmlExpr
  */
 static XmlExpr *
@@ -4525,6 +4541,9 @@ copyObject(const void *from)
 		case T_MinMaxExpr:
 			retval = _copyMinMaxExpr(from);
 			break;
+		case T_SQLValueFunction:
+			retval = _copySQLValueFunction(from);
+			break;
 		case T_XmlExpr:
 			retval = _copyXmlExpr(from);
 			break;