Turn the rangetable used by the executor into a flat list, and avoid storing

useless substructure for its RangeTblEntry nodes.  (I chose to keep using the
same struct node type and just zero out the link fields for unneeded info,
rather than making a separate ExecRangeTblEntry type --- it seemed too
fragile to have two different rangetable representations.)

Along the way, put subplans into a list in the toplevel PlannedStmt node,
and have SubPlan nodes refer to them by list index instead of direct pointers.
Vadim wanted to do that years ago, but I never understood what he was on about
until now.  It makes things a *whole* lot more robust, because we can stop
worrying about duplicate processing of subplans during expression tree
traversals.  That's been a constant source of bugs, and it's finally gone.

There are some consequent simplifications yet to be made, like not using
a separate EState for subplans in the executor, but I'll tackle that later.

1 files changed, 11 insertions, 39 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index 405b58f9fd6..d0df0ea6f47 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.287 2007/02/20 17:32:14 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.288 2007/02/22 22:00:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -92,9 +92,9 @@ static void ExecProcessReturning(ProjectionInfo *projectReturning,
 					 DestReceiver *dest);
 static TupleTableSlot *EvalPlanQualNext(EState *estate);
 static void EndEvalPlanQual(EState *estate);
+static void ExecCheckRTPerms(List *rangeTable);
 static void ExecCheckRTEPerms(RangeTblEntry *rte);
 static void ExecCheckXactReadOnly(PlannedStmt *plannedstmt);
-static void ExecCheckRangeTblReadOnly(List *rtable);
 static void EvalPlanQualStart(evalPlanQual *epq, EState *estate,
 				  evalPlanQual *priorepq);
 static void EvalPlanQualStop(evalPlanQual *epq);
@@ -348,16 +348,14 @@ ExecutorRewind(QueryDesc *queryDesc)
  * ExecCheckRTPerms
  *		Check access permissions for all relations listed in a range table.
  */
-void
+static void
 ExecCheckRTPerms(List *rangeTable)
 {
 	ListCell   *l;
 
 	foreach(l, rangeTable)
 	{
-		RangeTblEntry *rte = lfirst(l);
-
-		ExecCheckRTEPerms(rte);
+		ExecCheckRTEPerms((RangeTblEntry *) lfirst(l));
 	}
 }
 
@@ -373,12 +371,9 @@ ExecCheckRTEPerms(RangeTblEntry *rte)
 	Oid			userid;
 
 	/*
-	 * Only plain-relation RTEs need to be checked here.  Subquery RTEs are
-	 * checked by ExecInitSubqueryScan if the subquery is still a separate
-	 * subquery --- if it's been pulled up into our query level then the RTEs
-	 * are in our rangetable and will be checked here. Function RTEs are
+	 * Only plain-relation RTEs need to be checked here.  Function RTEs are
 	 * checked by init_fcache when the function is prepared for execution.
-	 * Join and special RTEs need no checks.
+	 * Join, subquery, and special RTEs need no checks.
 	 */
 	if (rte->rtekind != RTE_RELATION)
 		return;
@@ -417,6 +412,8 @@ ExecCheckRTEPerms(RangeTblEntry *rte)
 static void
 ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
 {
+	ListCell   *l;
+
 	/*
 	 * CREATE TABLE AS or SELECT INTO?
 	 *
@@ -426,32 +423,9 @@ ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
 		goto fail;
 
 	/* Fail if write permissions are requested on any non-temp table */
-	ExecCheckRangeTblReadOnly(plannedstmt->rtable);
-
-	return;
-
-fail:
-	ereport(ERROR,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("transaction is read-only")));
-}
-
-static void
-ExecCheckRangeTblReadOnly(List *rtable)
-{
-	ListCell   *l;
-
-	/* Fail if write permissions are requested on any non-temp table */
-	foreach(l, rtable)
+	foreach(l, plannedstmt->rtable)
 	{
-		RangeTblEntry *rte = lfirst(l);
-
-		if (rte->rtekind == RTE_SUBQUERY)
-		{
-			Assert(!rte->subquery->into);
-			ExecCheckRangeTblReadOnly(rte->subquery->rtable);
-			continue;
-		}
+		RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
 
 		if (rte->rtekind != RTE_RELATION)
 			continue;
@@ -494,9 +468,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	ListCell   *l;
 
 	/*
-	 * Do permissions checks.  It's sufficient to examine the query's top
-	 * rangetable here --- subplan RTEs will be checked during
-	 * ExecInitSubPlan().
+	 * Do permissions checks
 	 */
 	ExecCheckRTPerms(rangeTable);