Improve tuplestore.c to support multiple concurrent read positions.

This facility replaces the former mark/restore support but is otherwise
upward-compatible with previous uses.  It's expected to be needed for
single evaluation of CTEs and also for window functions, so I'm committing
it separately instead of waiting for either one of those patches to be
finished.  Per discussion with Greg Stark and Hitoshi Harada.

Note: I removed nodeFunctionscan's mark/restore support, instead of bothering
to update it for this change, because it was dead code anyway.

1 files changed, 4 insertions, 37 deletions

diff --git a/src/backend/executor/nodeFunctionscan.c b/src/backend/executor/nodeFunctionscan.c
index 6bbb5b139b6..6113a2c9067 100644
--- a/src/backend/executor/nodeFunctionscan.c
+++ b/src/backend/executor/nodeFunctionscan.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeFunctionscan.c,v 1.46 2008/02/29 02:49:39 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeFunctionscan.c,v 1.47 2008/10/01 19:51:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -131,6 +131,9 @@ ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
 	TypeFuncClass functypclass;
 	TupleDesc	tupdesc = NULL;
 
+	/* check for unsupported flags */
+	Assert(!(eflags & EXEC_FLAG_MARK));
+
 	/*
 	 * FunctionScan should not have any children.
 	 */
@@ -274,42 +277,6 @@ ExecEndFunctionScan(FunctionScanState *node)
 }
 
 /* ----------------------------------------------------------------
- *		ExecFunctionMarkPos
- *
- *		Calls tuplestore to save the current position in the stored file.
- * ----------------------------------------------------------------
- */
-void
-ExecFunctionMarkPos(FunctionScanState *node)
-{
-	/*
-	 * if we haven't materialized yet, just return.
-	 */
-	if (!node->tuplestorestate)
-		return;
-
-	tuplestore_markpos(node->tuplestorestate);
-}
-
-/* ----------------------------------------------------------------
- *		ExecFunctionRestrPos
- *
- *		Calls tuplestore to restore the last saved file position.
- * ----------------------------------------------------------------
- */
-void
-ExecFunctionRestrPos(FunctionScanState *node)
-{
-	/*
-	 * if we haven't materialized yet, just return.
-	 */
-	if (!node->tuplestorestate)
-		return;
-
-	tuplestore_restorepos(node->tuplestorestate);
-}
-
-/* ----------------------------------------------------------------
  *		ExecFunctionReScan
  *
  *		Rescans the relation.