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, 43 insertions, 0 deletions

diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index fc93063ed0b..b7b82bfb6b1 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -1761,6 +1761,49 @@ FigureColnameInternal(Node *node, char **name)
 					return 2;
 			}
 			break;
+		case T_SQLValueFunction:
+			/* make these act like a function or variable */
+			switch (((SQLValueFunction *) node)->op)
+			{
+				case SVFOP_CURRENT_DATE:
+					*name = "current_date";
+					return 2;
+				case SVFOP_CURRENT_TIME:
+				case SVFOP_CURRENT_TIME_N:
+					*name = "current_time";
+					return 2;
+				case SVFOP_CURRENT_TIMESTAMP:
+				case SVFOP_CURRENT_TIMESTAMP_N:
+					*name = "current_timestamp";
+					return 2;
+				case SVFOP_LOCALTIME:
+				case SVFOP_LOCALTIME_N:
+					*name = "localtime";
+					return 2;
+				case SVFOP_LOCALTIMESTAMP:
+				case SVFOP_LOCALTIMESTAMP_N:
+					*name = "localtimestamp";
+					return 2;
+				case SVFOP_CURRENT_ROLE:
+					*name = "current_role";
+					return 2;
+				case SVFOP_CURRENT_USER:
+					*name = "current_user";
+					return 2;
+				case SVFOP_USER:
+					*name = "user";
+					return 2;
+				case SVFOP_SESSION_USER:
+					*name = "session_user";
+					return 2;
+				case SVFOP_CURRENT_CATALOG:
+					*name = "current_catalog";
+					return 2;
+				case SVFOP_CURRENT_SCHEMA:
+					*name = "current_schema";
+					return 2;
+			}
+			break;
 		case T_XmlExpr:
 			/* make SQL/XML functions act like a regular function */
 			switch (((XmlExpr *) node)->op)