Switch SQLValueFunction on "name" to use COERCE_SQL_SYNTAX

This commit changes six SQL keywords to use COERCE_SQL_SYNTAX rather
than relying on SQLValueFunction:
- CURRENT_ROLE
- CURRENT_USER
- USER
- SESSION_USER
- CURRENT_CATALOG
- CURRENT_SCHEMA

Among the six, "user", "current_role" and "current_catalog" require
specific SQL functions to allow ruleutils.c to map them to the SQL
keywords these require when using COERCE_SQL_SYNTAX.  Having
pg_proc.proname match with the keyword ensures that the compatibility
remains the same when projecting any of these keywords in a FROM clause
to an attribute name when an alias is not specified.  This is covered by
the tests added in 2e0d80c, making sure that a correct mapping happens
with each SQL keyword.  The three others (current_schema, session_user
and current_user) already have pg_proc entries for this job, so this
brings more consistency between the way such keywords are treated in the
parser, the executor and ruleutils.c.

SQLValueFunction is reduced to half its contents after this change,
simplifying its logic a bit as there is no need to enforce a C collation
anymore for the entries returning a name as a result.  I have made a few
performance tests, with a million-ish calls to these keywords without
seeing a difference in run-time or in perf profiles
(ExecEvalSQLValueFunction() is removed from the profiles).  The
remaining SQLValueFunctions are now related to timestamps and dates.

Bump catalog version.

Reviewed-by: Corey Huinker
Discussion: https://postgr.es/m/[email protected]

9 files changed, 56 insertions, 93 deletions

diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 9b9bbf00a9..6ebf5c287e 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -2495,15 +2495,10 @@ ExecEvalParamExtern(ExprState *state, ExprEvalStep *op, ExprContext *econtext)
 void
 ExecEvalSQLValueFunction(ExprState *state, ExprEvalStep *op)
 {
-	LOCAL_FCINFO(fcinfo, 0);
 	SQLValueFunction *svf = op->d.sqlvaluefunction.svf;
 
 	*op->resnull = false;
 
-	/*
-	 * Note: current_schema() can return NULL.  current_user() etc currently
-	 * cannot, but might as well code those cases the same way for safety.
-	 */
 	switch (svf->op)
 	{
 		case SVFOP_CURRENT_DATE:
@@ -2525,28 +2520,6 @@ ExecEvalSQLValueFunction(ExprState *state, ExprEvalStep *op)
 		case SVFOP_LOCALTIMESTAMP_N:
 			*op->resvalue = TimestampGetDatum(GetSQLLocalTimestamp(svf->typmod));
 			break;
-		case SVFOP_CURRENT_ROLE:
-		case SVFOP_CURRENT_USER:
-		case SVFOP_USER:
-			InitFunctionCallInfoData(*fcinfo, NULL, 0, InvalidOid, NULL, NULL);
-			*op->resvalue = current_user(fcinfo);
-			*op->resnull = fcinfo->isnull;
-			break;
-		case SVFOP_SESSION_USER:
-			InitFunctionCallInfoData(*fcinfo, NULL, 0, InvalidOid, NULL, NULL);
-			*op->resvalue = session_user(fcinfo);
-			*op->resnull = fcinfo->isnull;
-			break;
-		case SVFOP_CURRENT_CATALOG:
-			InitFunctionCallInfoData(*fcinfo, NULL, 0, InvalidOid, NULL, NULL);
-			*op->resvalue = current_database(fcinfo);
-			*op->resnull = fcinfo->isnull;
-			break;
-		case SVFOP_CURRENT_SCHEMA:
-			InitFunctionCallInfoData(*fcinfo, NULL, 0, InvalidOid, NULL, NULL);
-			*op->resvalue = current_schema(fcinfo);
-			*op->resnull = fcinfo->isnull;
-			break;
 	}
 }
 
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 0a7b22f97e..2585a3175c 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -917,11 +917,8 @@ exprCollation(const Node *expr)
 			coll = ((const MinMaxExpr *) expr)->minmaxcollid;
 			break;
 		case T_SQLValueFunction:
-			/* Returns either NAME or a non-collatable type */
-			if (((const SQLValueFunction *) expr)->type == NAMEOID)
-				coll = C_COLLATION_OID;
-			else
-				coll = InvalidOid;
+			/* Returns a non-collatable type */
+			coll = InvalidOid;
 			break;
 		case T_XmlExpr:
 
@@ -1144,9 +1141,7 @@ exprSetCollation(Node *expr, Oid collation)
 			((MinMaxExpr *) expr)->minmaxcollid = collation;
 			break;
 		case T_SQLValueFunction:
-			Assert((((SQLValueFunction *) expr)->type == NAMEOID) ?
-				   (collation == C_COLLATION_OID) :
-				   (collation == InvalidOid));
+			Assert(collation == InvalidOid);
 			break;
 		case T_XmlExpr:
 			Assert((((XmlExpr *) expr)->op == IS_XMLSERIALIZE) ?
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 2a910ded15..9054742427 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -15231,15 +15231,24 @@ func_expr_common_subexpr:
 				}
 			| CURRENT_ROLE
 				{
-					$$ = makeSQLValueFunction(SVFOP_CURRENT_ROLE, -1, @1);
+					$$ = (Node *) makeFuncCall(SystemFuncName("current_role"),
+											   NIL,
+											   COERCE_SQL_SYNTAX,
+											   @1);
 				}
 			| CURRENT_USER
 				{
-					$$ = makeSQLValueFunction(SVFOP_CURRENT_USER, -1, @1);
+					$$ = (Node *) makeFuncCall(SystemFuncName("current_user"),
+											   NIL,
+											   COERCE_SQL_SYNTAX,
+											   @1);
 				}
 			| SESSION_USER
 				{
-					$$ = makeSQLValueFunction(SVFOP_SESSION_USER, -1, @1);
+					$$ = (Node *) makeFuncCall(SystemFuncName("session_user"),
+											   NIL,
+											   COERCE_SQL_SYNTAX,
+											   @1);
 				}
 			| SYSTEM_USER
 				{
@@ -15250,15 +15259,24 @@ func_expr_common_subexpr:
 				}
 			| USER
 				{
-					$$ = makeSQLValueFunction(SVFOP_USER, -1, @1);
+					$$ = (Node *) makeFuncCall(SystemFuncName("user"),
+											   NIL,
+											   COERCE_SQL_SYNTAX,
+											   @1);
 				}
 			| CURRENT_CATALOG
 				{
-					$$ = makeSQLValueFunction(SVFOP_CURRENT_CATALOG, -1, @1);
+					$$ = (Node *) makeFuncCall(SystemFuncName("current_catalog"),
+											   NIL,
+											   COERCE_SQL_SYNTAX,
+											   @1);
 				}
 			| CURRENT_SCHEMA
 				{
-					$$ = makeSQLValueFunction(SVFOP_CURRENT_SCHEMA, -1, @1);
+					$$ = (Node *) makeFuncCall(SystemFuncName("current_schema"),
+											   NIL,
+											   COERCE_SQL_SYNTAX,
+											   @1);
 				}
 			| CAST '(' a_expr AS Typename ')'
 				{ $$ = makeTypeCast($3, $5, @1); }
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index e5fc708c8a..0fdbf82f3a 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -2231,14 +2231,6 @@ transformSQLValueFunction(ParseState *pstate, SQLValueFunction *svf)
 			svf->type = TIMESTAMPOID;
 			svf->typmod = anytimestamp_typmod_check(false, svf->typmod);
 			break;
-		case SVFOP_CURRENT_ROLE:
-		case SVFOP_CURRENT_USER:
-		case SVFOP_USER:
-		case SVFOP_SESSION_USER:
-		case SVFOP_CURRENT_CATALOG:
-		case SVFOP_CURRENT_SCHEMA:
-			svf->type = NAMEOID;
-			break;
 	}
 
 	return (Node *) svf;
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index bd8057bc3e..f54591a987 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -1895,24 +1895,6 @@ FigureColnameInternal(Node *node, char **name)
 				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:
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index b4c0407588..129f3333fb 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -9169,24 +9169,6 @@ get_rule_expr(Node *node, deparse_context *context,
 						appendStringInfo(buf, "LOCALTIMESTAMP(%d)",
 										 svf->typmod);
 						break;
-					case SVFOP_CURRENT_ROLE:
-						appendStringInfoString(buf, "CURRENT_ROLE");
-						break;
-					case SVFOP_CURRENT_USER:
-						appendStringInfoString(buf, "CURRENT_USER");
-						break;
-					case SVFOP_USER:
-						appendStringInfoString(buf, "USER");
-						break;
-					case SVFOP_SESSION_USER:
-						appendStringInfoString(buf, "SESSION_USER");
-						break;
-					case SVFOP_CURRENT_CATALOG:
-						appendStringInfoString(buf, "CURRENT_CATALOG");
-						break;
-					case SVFOP_CURRENT_SCHEMA:
-						appendStringInfoString(buf, "CURRENT_SCHEMA");
-						break;
 				}
 			}
 			break;
@@ -10288,6 +10270,24 @@ get_func_sql_syntax(FuncExpr *expr, deparse_context *context)
 			appendStringInfoChar(buf, ')');
 			return true;
 
+		case F_CURRENT_CATALOG:
+			appendStringInfoString(buf, "CURRENT_CATALOG");
+			return true;
+		case F_CURRENT_ROLE:
+			appendStringInfoString(buf, "CURRENT_ROLE");
+			return true;
+		case F_CURRENT_SCHEMA:
+			appendStringInfoString(buf, "CURRENT_SCHEMA");
+			return true;
+		case F_CURRENT_USER:
+			appendStringInfoString(buf, "CURRENT_USER");
+			return true;
+		case F_USER:
+			appendStringInfoString(buf, "USER");
+			return true;
+		case F_SESSION_USER:
+			appendStringInfoString(buf, "SESSION_USER");
+			return true;
 		case F_SYSTEM_USER:
 			appendStringInfoString(buf, "SYSTEM_USER");
 			return true;
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 775e3a5db5..ac2043f6cc 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -57,6 +57,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202211181
+#define CATALOG_VERSION_NO	202211201
 
 #endif
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 9dbe9ec801..fd2559442e 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -1505,6 +1505,15 @@
 { oid => '745', descr => 'current user name',
   proname => 'current_user', provolatile => 's', prorettype => 'name',
   proargtypes => '', prosrc => 'current_user' },
+{ oid => '9695', descr => 'current role name',
+  proname => 'current_role', provolatile => 's', prorettype => 'name',
+  proargtypes => '', prosrc => 'current_user' },
+{ oid => '9696', descr => 'user name',
+  proname => 'user', provolatile => 's', prorettype => 'name',
+  proargtypes => '', prosrc => 'current_user' },
+{ oid => '9697', descr => 'name of the current database',
+  proname => 'current_catalog', provolatile => 's', prorettype => 'name',
+  proargtypes => '', prosrc => 'current_database' },
 { oid => '746', descr => 'session user name',
   proname => 'session_user', provolatile => 's', prorettype => 'name',
   proargtypes => '', prosrc => 'session_user' },
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index f71f551782..f6dd27edcc 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -1313,13 +1313,7 @@ typedef enum SQLValueFunctionOp
 	SVFOP_LOCALTIME,
 	SVFOP_LOCALTIME_N,
 	SVFOP_LOCALTIMESTAMP,
-	SVFOP_LOCALTIMESTAMP_N,
-	SVFOP_CURRENT_ROLE,
-	SVFOP_CURRENT_USER,
-	SVFOP_USER,
-	SVFOP_SESSION_USER,
-	SVFOP_CURRENT_CATALOG,
-	SVFOP_CURRENT_SCHEMA
+	SVFOP_LOCALTIMESTAMP_N
 } SQLValueFunctionOp;
 
 typedef struct SQLValueFunction