Remove the t_datamcxt field of HeapTupleData. This was introduced for

the convenience of tuptoaster.c and is no longer needed, so may as well
get rid of some small amount of overhead.

13 files changed, 24 insertions, 66 deletions

diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index 5551f744bb..69634b5763 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -16,7 +16,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.102 2005/10/19 22:30:30 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/common/heaptuple.c,v 1.103 2005/11/20 19:49:06 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -623,7 +623,6 @@ heap_copytuple(HeapTuple tuple)
 	newTuple->t_len = tuple->t_len;
 	newTuple->t_self = tuple->t_self;
 	newTuple->t_tableOid = tuple->t_tableOid;
-	newTuple->t_datamcxt = CurrentMemoryContext;
 	newTuple->t_data = (HeapTupleHeader) ((char *) newTuple + HEAPTUPLESIZE);
 	memcpy((char *) newTuple->t_data, (char *) tuple->t_data, tuple->t_len);
 	return newTuple;
@@ -647,7 +646,6 @@ heap_copytuple_with_tuple(HeapTuple src, HeapTuple dest)
 	dest->t_len = src->t_len;
 	dest->t_self = src->t_self;
 	dest->t_tableOid = src->t_tableOid;
-	dest->t_datamcxt = CurrentMemoryContext;
 	dest->t_data = (HeapTupleHeader) palloc(src->t_len);
 	memcpy((char *) dest->t_data, (char *) src->t_data, src->t_len);
 }
@@ -725,7 +723,6 @@ heap_form_tuple(TupleDesc tupleDescriptor,
 	 * HeapTupleData management structure are allocated in one chunk.
 	 */
 	tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + len);
-	tuple->t_datamcxt = CurrentMemoryContext;
 	tuple->t_data = td = (HeapTupleHeader) ((char *) tuple + HEAPTUPLESIZE);
 
 	/*
@@ -833,7 +830,6 @@ heap_formtuple(TupleDesc tupleDescriptor,
 	 * HeapTupleData management structure are allocated in one chunk.
 	 */
 	tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + len);
-	tuple->t_datamcxt = CurrentMemoryContext;
 	tuple->t_data = td = (HeapTupleHeader) ((char *) tuple + HEAPTUPLESIZE);
 
 	/*
@@ -1516,11 +1512,6 @@ slot_attisnull(TupleTableSlot *slot, int attnum)
 void
 heap_freetuple(HeapTuple htup)
 {
-	if (htup->t_data != NULL)
-		if (htup->t_datamcxt != NULL && (char *) (htup->t_data) !=
-			((char *) htup + HEAPTUPLESIZE))
-			pfree(htup->t_data);
-
 	pfree(htup);
 }
 
@@ -1559,7 +1550,6 @@ heap_addheader(int natts,		/* max domain index */
 	len = hoff + structlen;
 
 	tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + len);
-	tuple->t_datamcxt = CurrentMemoryContext;
 	tuple->t_data = td = (HeapTupleHeader) ((char *) tuple + HEAPTUPLESIZE);
 
 	tuple->t_len = len;
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index fc750884c7..3b4de80b7b 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.201 2005/11/20 18:38:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.202 2005/11/20 19:49:07 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -78,7 +78,6 @@ initscan(HeapScanDesc scan, ScanKey key)
 	 */
 	scan->rs_nblocks = RelationGetNumberOfBlocks(scan->rs_rd);
 
-	scan->rs_ctup.t_datamcxt = NULL;
 	scan->rs_ctup.t_data = NULL;
 	scan->rs_cbuf = InvalidBuffer;
 
@@ -129,8 +128,9 @@ heapgettup(Relation relation,
 	/*
 	 * debugging stuff
 	 *
-	 * check validity of arguments, here and for other functions too Note: no
-	 * locking manipulations needed--this is a local function
+	 * check validity of arguments, here and for other functions too
+	 *
+	 * Note: no locking manipulations needed--this is a local function
 	 */
 #ifdef	HEAPDEBUGALL
 	if (ItemPointerIsValid(tid))
@@ -164,7 +164,6 @@ heapgettup(Relation relation,
 		if (BufferIsValid(*buffer))
 			ReleaseBuffer(*buffer);
 		*buffer = InvalidBuffer;
-		tuple->t_datamcxt = NULL;
 		tuple->t_data = NULL;
 		return;
 	}
@@ -182,7 +181,6 @@ heapgettup(Relation relation,
 			if (BufferIsValid(*buffer))
 				ReleaseBuffer(*buffer);
 			*buffer = InvalidBuffer;
-			tuple->t_datamcxt = NULL;
 			tuple->t_data = NULL;
 			return;
 		}
@@ -197,7 +195,6 @@ heapgettup(Relation relation,
 		lineoff = ItemPointerGetOffsetNumber(tid);
 		lpp = PageGetItemId(dp, lineoff);
 
-		tuple->t_datamcxt = NULL;
 		tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
 		tuple->t_len = ItemIdGetLength(lpp);
 		LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
@@ -293,7 +290,6 @@ heapgettup(Relation relation,
 			{
 				bool		valid;
 
-				tuple->t_datamcxt = NULL;
 				tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
 				tuple->t_len = ItemIdGetLength(lpp);
 				ItemPointerSet(&(tuple->t_self), page, lineoff);
@@ -340,7 +336,6 @@ heapgettup(Relation relation,
 			if (BufferIsValid(*buffer))
 				ReleaseBuffer(*buffer);
 			*buffer = InvalidBuffer;
-			tuple->t_datamcxt = NULL;
 			tuple->t_data = NULL;
 			return;
 		}
@@ -872,7 +867,6 @@ heap_release_fetch(Relation relation,
 			ReleaseBuffer(buffer);
 			*userbuf = InvalidBuffer;
 		}
-		tuple->t_datamcxt = NULL;
 		tuple->t_data = NULL;
 		return false;
 	}
@@ -895,7 +889,6 @@ heap_release_fetch(Relation relation,
 			ReleaseBuffer(buffer);
 			*userbuf = InvalidBuffer;
 		}
-		tuple->t_datamcxt = NULL;
 		tuple->t_data = NULL;
 		return false;
 	}
@@ -903,7 +896,6 @@ heap_release_fetch(Relation relation,
 	/*
 	 * fill in *tuple fields
 	 */
-	tuple->t_datamcxt = NULL;
 	tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
 	tuple->t_len = ItemIdGetLength(lp);
 	tuple->t_tableOid = RelationGetRelid(relation);
@@ -1027,7 +1019,6 @@ heap_get_latest_tid(Relation relation,
 
 		/* OK to access the tuple */
 		tp.t_self = ctid;
-		tp.t_datamcxt = NULL;
 		tp.t_data = (HeapTupleHeader) PageGetItem(dp, lp);
 		tp.t_len = ItemIdGetLength(lp);
 
@@ -1303,7 +1294,6 @@ heap_delete(Relation relation, ItemPointer tid,
 	dp = (PageHeader) BufferGetPage(buffer);
 	lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(tid));
 
-	tp.t_datamcxt = NULL;
 	tp.t_data = (HeapTupleHeader) PageGetItem(dp, lp);
 	tp.t_len = ItemIdGetLength(lp);
 	tp.t_self = *tid;
@@ -1612,7 +1602,6 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 	dp = (PageHeader) BufferGetPage(buffer);
 	lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(otid));
 
-	oldtup.t_datamcxt = NULL;
 	oldtup.t_data = (HeapTupleHeader) PageGetItem(dp, lp);
 	oldtup.t_len = ItemIdGetLength(lp);
 	oldtup.t_self = *otid;
@@ -2093,7 +2082,6 @@ heap_lock_tuple(Relation relation, HeapTuple tuple, Buffer *buffer,
 	lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(tid));
 	Assert(ItemIdIsUsed(lp));
 
-	tuple->t_datamcxt = NULL;
 	tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
 	tuple->t_len = ItemIdGetLength(lp);
 	tuple->t_tableOid = RelationGetRelid(relation);
@@ -2476,13 +2464,11 @@ heap_restrpos(HeapScanDesc scan)
 
 	if (!ItemPointerIsValid(&scan->rs_mctid))
 	{
-		scan->rs_ctup.t_datamcxt = NULL;
 		scan->rs_ctup.t_data = NULL;
 	}
 	else
 	{
 		scan->rs_ctup.t_self = scan->rs_mctid;
-		scan->rs_ctup.t_datamcxt = NULL;
 		scan->rs_ctup.t_data = (HeapTupleHeader) 0x1;	/* for heapgettup */
 		heapgettup(scan->rs_rd,
 				   0,
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index 99d725c27c..c18ea54282 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.54 2005/11/20 18:38:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/tuptoaster.c,v 1.55 2005/11/20 19:49:07 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -774,7 +774,6 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup)
 		result_tuple->t_len = new_len;
 		result_tuple->t_self = newtup->t_self;
 		result_tuple->t_tableOid = newtup->t_tableOid;
-		result_tuple->t_datamcxt = CurrentMemoryContext;
 		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
 		result_tuple->t_data = new_data;
 
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index ed604f9c5d..5563b9d597 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.49 2005/10/15 02:49:09 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/index/genam.c,v 1.50 2005/11/20 19:49:07 tgl Exp $
  *
  * NOTES
  *	  many of the old access method routines have been turned into
@@ -98,7 +98,6 @@ RelationGetIndexScan(Relation indexRelation,
 	ItemPointerSetInvalid(&scan->currentMarkData);
 
 	ItemPointerSetInvalid(&scan->xs_ctup.t_self);
-	scan->xs_ctup.t_datamcxt = NULL;
 	scan->xs_ctup.t_data = NULL;
 	scan->xs_cbuf = InvalidBuffer;
 
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index a3f7c37dc2..81463abba8 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.195 2005/10/15 02:49:15 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.196 2005/11/20 19:49:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1769,7 +1769,6 @@ ltrmark:;
 
 		Assert(ItemIdIsUsed(lp));
 
-		tuple.t_datamcxt = NULL;
 		tuple.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
 		tuple.t_len = ItemIdGetLength(lp);
 		tuple.t_self = *tid;
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 506eb23e70..af384cebcd 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -13,7 +13,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.317 2005/10/15 02:49:16 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.318 2005/11/20 19:49:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1338,7 +1338,6 @@ scan_heap(VRelStats *vacrelstats, Relation onerel,
 				continue;
 			}
 
-			tuple.t_datamcxt = NULL;
 			tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
 			tuple.t_len = ItemIdGetLength(itemid);
 			ItemPointerSet(&(tuple.t_self), blkno, offnum);
@@ -1758,7 +1757,6 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
 			if (!ItemIdIsUsed(itemid))
 				continue;
 
-			tuple.t_datamcxt = NULL;
 			tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
 			tuple_len = tuple.t_len = ItemIdGetLength(itemid);
 			ItemPointerSet(&(tuple.t_self), blkno, offnum);
@@ -1937,7 +1935,6 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
 						break;
 					}
 					/* OK, switch our attention to the next tuple in chain */
-					tp.t_datamcxt = NULL;
 					tp.t_data = nextTdata;
 					tp.t_self = nextTid;
 					tlen = tp.t_len = ItemIdGetLength(nextItemid);
@@ -2064,7 +2061,6 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
 						chain_move_failed = true;
 						break;	/* out of check-all-items loop */
 					}
-					tp.t_datamcxt = NULL;
 					tp.t_data = PTdata;
 					tlen = tp.t_len = ItemIdGetLength(Pitemid);
 					if (freeCbuf)
@@ -2122,7 +2118,6 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
 
 					Citemid = PageGetItemId(Cpage,
 								ItemPointerGetOffsetNumber(&(tuple.t_self)));
-					tuple.t_datamcxt = NULL;
 					tuple.t_data = (HeapTupleHeader) PageGetItem(Cpage, Citemid);
 					tuple_len = tuple.t_len = ItemIdGetLength(Citemid);
 
@@ -2582,7 +2577,6 @@ move_chain_tuple(Relation rel,
 	newitemid = PageGetItemId(dst_page, newoff);
 	/* drop temporary copy, and point to the version on the dest page */
 	pfree(newtup.t_data);
-	newtup.t_datamcxt = NULL;
 	newtup.t_data = (HeapTupleHeader) PageGetItem(dst_page, newitemid);
 
 	ItemPointerSet(&(newtup.t_self), dst_vacpage->blkno, newoff);
@@ -2692,7 +2686,6 @@ move_plain_tuple(Relation rel,
 			 dst_vacpage->offsets_used, dst_vacpage->offsets_free);
 	newitemid = PageGetItemId(dst_page, newoff);
 	pfree(newtup.t_data);
-	newtup.t_datamcxt = NULL;
 	newtup.t_data = (HeapTupleHeader) PageGetItem(dst_page, newitemid);
 	ItemPointerSet(&(newtup.t_data->t_ctid), dst_vacpage->blkno, newoff);
 	newtup.t_self = newtup.t_data->t_ctid;
diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
index 7f27619901..d0b1d3a6fb 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -31,7 +31,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.61 2005/10/15 02:49:16 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.62 2005/11/20 19:49:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -349,7 +349,6 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
 				continue;
 			}
 
-			tuple.t_datamcxt = NULL;
 			tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
 			tuple.t_len = ItemIdGetLength(itemid);
 			ItemPointerSet(&(tuple.t_self), blkno, offnum);
@@ -885,7 +884,6 @@ count_nondeletable_pages(Relation onerel, LVRelStats *vacrelstats)
 			if (!ItemIdIsUsed(itemid))
 				continue;
 
-			tuple.t_datamcxt = NULL;
 			tuple.t_data = (HeapTupleHeader) PageGetItem(page, itemid);
 			tuple.t_len = ItemIdGetLength(itemid);
 			ItemPointerSet(&(tuple.t_self), blkno, offnum);
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 8c51e785b2..06978d1f98 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.96 2005/10/15 02:49:17 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeHash.c,v 1.97 2005/11/20 19:49:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -621,7 +621,6 @@ ExecHashTableInsert(HashJoinTable hashtable,
 		memcpy((char *) &hashTuple->htup,
 			   (char *) tuple,
 			   sizeof(hashTuple->htup));
-		hashTuple->htup.t_datamcxt = hashtable->batchCxt;
 		hashTuple->htup.t_data = (HeapTupleHeader)
 			(((char *) hashTuple) + MAXALIGN(sizeof(HashJoinTupleData)));
 		memcpy((char *) hashTuple->htup.t_data,
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 817f3822ef..856fe67732 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeHashjoin.c,v 1.75 2005/10/18 01:06:24 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeHashjoin.c,v 1.76 2005/11/20 19:49:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -789,7 +789,6 @@ ExecHashJoinGetSavedTuple(HashJoinState *hjstate,
 				 errmsg("could not read from hash-join temporary file: %m")));
 	heapTuple = palloc(HEAPTUPLESIZE + htup.t_len);
 	memcpy((char *) heapTuple, (char *) &htup, sizeof(HeapTupleData));
-	heapTuple->t_datamcxt = CurrentMemoryContext;
 	heapTuple->t_data = (HeapTupleHeader)
 		((char *) heapTuple + HEAPTUPLESIZE);
 	nread = BufFileRead(file, (void *) heapTuple->t_data, htup.t_len);
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index e877c1f828..2b58874ac7 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.230 2005/10/15 02:49:31 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.231 2005/11/20 19:49:07 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2998,7 +2998,6 @@ load_relcache_init_file(void)
 				goto read_failed;
 
 			/* Fix up internal pointers in the tuple -- see heap_copytuple */
-			rel->rd_indextuple->t_datamcxt = CurrentMemoryContext;
 			rel->rd_indextuple->t_data = (HeapTupleHeader) ((char *) rel->rd_indextuple + HEAPTUPLESIZE);
 			rel->rd_index = (Form_pg_index) GETSTRUCT(rel->rd_indextuple);
 
diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index d38d5e2d41..38120575f6 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -78,7 +78,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/sort/tuplesort.c,v 1.54 2005/10/25 13:47:08 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/sort/tuplesort.c,v 1.55 2005/11/20 19:49:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2071,7 +2071,6 @@ readtup_heap(Tuplesortstate *state, int tapenum, unsigned int len)
 	/* reconstruct the HeapTupleData portion */
 	tuple->t_len = len - sizeof(unsigned int);
 	ItemPointerSetInvalid(&(tuple->t_self));
-	tuple->t_datamcxt = CurrentMemoryContext;
 	tuple->t_data = (HeapTupleHeader) (((char *) tuple) + HEAPTUPLESIZE);
 	/* read in the tuple proper */
 	if (LogicalTapeRead(state->tapeset, tapenum, (void *) tuple->t_data,
diff --git a/src/backend/utils/sort/tuplestore.c b/src/backend/utils/sort/tuplestore.c
index d409121418..bdd04e21f4 100644
--- a/src/backend/utils/sort/tuplestore.c
+++ b/src/backend/utils/sort/tuplestore.c
@@ -36,7 +36,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/sort/tuplestore.c,v 1.23 2005/10/15 02:49:37 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/sort/tuplestore.c,v 1.24 2005/11/20 19:49:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -707,7 +707,6 @@ readtup_heap(Tuplestorestate *state, unsigned int len)
 	/* reconstruct the HeapTupleData portion */
 	tuple->t_len = len - sizeof(unsigned int);
 	ItemPointerSetInvalid(&(tuple->t_self));
-	tuple->t_datamcxt = CurrentMemoryContext;
 	tuple->t_data = (HeapTupleHeader) (((char *) tuple) + HEAPTUPLESIZE);
 	/* read in the tuple proper */
 	if (BufFileRead(state->myfile, (void *) tuple->t_data,
diff --git a/src/include/access/htup.h b/src/include/access/htup.h
index f6fbd8f04a..3a10fa34fd 100644
--- a/src/include/access/htup.h
+++ b/src/include/access/htup.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.78 2005/10/15 02:49:42 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.79 2005/11/20 19:49:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -361,20 +361,20 @@ do { \
  *
  * * Pointer to a tuple in a disk buffer: t_data points directly into the
  *	 buffer (which the code had better be holding a pin on, but this is not
- *	 reflected in HeapTupleData itself).  t_datamcxt must be NULL.
+ *	 reflected in HeapTupleData itself).
  *
- * * Pointer to nothing: t_data and t_datamcxt are NULL.  This is used as
- *	 a failure indication in some functions.
+ * * Pointer to nothing: t_data is NULL.  This is used as a failure indication
+ *	 in some functions.
  *
  * * Part of a palloc'd tuple: the HeapTupleData itself and the tuple
  *	 form a single palloc'd chunk.  t_data points to the memory location
- *	 immediately following the HeapTupleData struct (at offset HEAPTUPLESIZE),
- *	 and t_datamcxt is the containing context.	This is used as the output
- *	 format of heap_form_tuple and related routines.
+ *	 immediately following the HeapTupleData struct (at offset HEAPTUPLESIZE).
+ *	 This is the output format of heap_form_tuple and related routines.
  *
  * * Separately allocated tuple: t_data points to a palloc'd chunk that
- *	 is not adjacent to the HeapTupleData, and t_datamcxt is the context
- *	 containing that chunk.
+ *	 is not adjacent to the HeapTupleData.  (This case is deprecated since
+ *	 it's difficult to tell apart from case #1.  It should be used only in
+ *	 limited contexts where the code knows that case #1 will never apply.)
  *
  * t_len should always be valid, except in the pointer-to-nothing case.
  * t_self and t_tableOid should be valid if the HeapTupleData points to
@@ -386,7 +386,6 @@ typedef struct HeapTupleData
 	uint32		t_len;			/* length of *t_data */
 	ItemPointerData t_self;		/* SelfItemPointer */
 	Oid			t_tableOid;		/* table the tuple came from */
-	MemoryContext t_datamcxt;	/* memory context of allocation */
 	HeapTupleHeader t_data;		/* -> tuple header and data */
 } HeapTupleData;