Replace the array-style TupleTable data structure with a simple List of

TupleTableSlot nodes.  This eliminates the need to count in advance
how many Slots will be needed, which seems more than worth the small
increase in the amount of palloc traffic during executor startup.

The ExecCountSlots infrastructure is now all dead code, but I'll remove it
in a separate commit for clarity.

Per a comment from Robert Haas.

1 files changed, 6 insertions, 19 deletions

diff --git a/src/include/executor/tuptable.h b/src/include/executor/tuptable.h
index 879a310c68b..ffac7e01620 100644
--- a/src/include/executor/tuptable.h
+++ b/src/include/executor/tuptable.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/executor/tuptable.h,v 1.42 2009/06/11 14:49:11 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/executor/tuptable.h,v 1.43 2009/09/27 20:09:57 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -19,7 +19,7 @@
 #include "storage/buf.h"
 
 /*----------
- * The executor stores tuples in a "tuple table" which is composed of
+ * The executor stores tuples in a "tuple table" which is a List of
  * independent TupleTableSlots.  There are several cases we need to handle:
  *		1. physical tuple in a disk buffer page
  *		2. physical tuple constructed in palloc'ed memory
@@ -112,7 +112,7 @@
  */
 typedef struct TupleTableSlot
 {
-	NodeTag		type;			/* vestigial ... allows IsA tests */
+	NodeTag		type;
 	bool		tts_isempty;	/* true = slot is empty */
 	bool		tts_shouldFree; /* should pfree tts_tuple? */
 	bool		tts_shouldFreeMin;		/* should pfree tts_mintuple? */
@@ -133,30 +133,17 @@ typedef struct TupleTableSlot
 	((slot)->tts_tuple != NULL && (slot)->tts_tuple != &((slot)->tts_minhdr))
 
 /*
- * Tuple table data structure: an array of TupleTableSlots.
- */
-typedef struct TupleTableData
-{
-	int			size;			/* size of the table (number of slots) */
-	int			next;			/* next available slot number */
-	TupleTableSlot array[1];	/* VARIABLE LENGTH ARRAY - must be last */
-} TupleTableData;				/* VARIABLE LENGTH STRUCT */
-
-typedef TupleTableData *TupleTable;
-
-
-/*
  * TupIsNull -- is a TupleTableSlot empty?
  */
 #define TupIsNull(slot) \
 	((slot) == NULL || (slot)->tts_isempty)
 
 /* in executor/execTuples.c */
-extern TupleTable ExecCreateTupleTable(int tableSize);
-extern void ExecDropTupleTable(TupleTable table, bool shouldFree);
+extern TupleTableSlot *MakeTupleTableSlot(void);
+extern TupleTableSlot *ExecAllocTableSlot(List **tupleTable);
+extern void ExecResetTupleTable(List *tupleTable, bool shouldFree);
 extern TupleTableSlot *MakeSingleTupleTableSlot(TupleDesc tupdesc);
 extern void ExecDropSingleTupleTableSlot(TupleTableSlot *slot);
-extern TupleTableSlot *ExecAllocTableSlot(TupleTable table);
 extern void ExecSetSlotDescriptor(TupleTableSlot *slot, TupleDesc tupdesc);
 extern TupleTableSlot *ExecStoreTuple(HeapTuple tuple,
 			   TupleTableSlot *slot,