Add the full set of comparison functions for type TID, including a btree

opclass.  This is not so much because anyone's likely to create an index
on TID, as that sorting TIDs can be useful.  Also added max and min
aggregates while at it, so that one can investigate the clusteredness of
a table with queries like SELECT min(ctid), max(ctid) FROM tab WHERE ...
Greg Stark and Tom Lane

1 files changed, 91 insertions, 13 deletions

diff --git a/src/backend/utils/adt/tid.c b/src/backend/utils/adt/tid.c
index 658108f56c2..814670521ea 100644
--- a/src/backend/utils/adt/tid.c
+++ b/src/backend/utils/adt/tid.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/tid.c,v 1.53 2006/07/14 05:28:28 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/tid.c,v 1.54 2006/07/21 20:51:32 tgl Exp $
  *
  * NOTES
  *	  input routine largely stolen from boxin().
@@ -98,16 +98,11 @@ Datum
 tidout(PG_FUNCTION_ARGS)
 {
 	ItemPointer itemPtr = PG_GETARG_ITEMPOINTER(0);
-	BlockId		blockId;
 	BlockNumber blockNumber;
 	OffsetNumber offsetNumber;
 	char		buf[32];
 
-	if (!ItemPointerIsValid(itemPtr))
-		PG_RETURN_CSTRING(pstrdup("()"));
-
-	blockId = &(itemPtr->ip_blkid);
-	blockNumber = BlockIdGetBlockNumber(blockId);
+	blockNumber = BlockIdGetBlockNumber(&(itemPtr->ip_blkid));
 	offsetNumber = itemPtr->ip_posid;
 
 	/* Perhaps someday we should output this as a record. */
@@ -163,15 +158,36 @@ tidsend(PG_FUNCTION_ARGS)
  *	 PUBLIC ROUTINES														 *
  *****************************************************************************/
 
+static int32
+tid_cmp_internal(ItemPointer arg1, ItemPointer arg2)
+{
+	/*
+	 * Don't use ItemPointerGetBlockNumber or ItemPointerGetOffsetNumber here,
+	 * because they assert ip_posid != 0 which might not be true for a
+	 * user-supplied TID.
+	 */
+	BlockNumber b1 = BlockIdGetBlockNumber(&(arg1->ip_blkid));
+	BlockNumber b2 = BlockIdGetBlockNumber(&(arg2->ip_blkid));
+	
+	if (b1 < b2)
+		return -1;
+	else if (b1 > b2)
+		return 1;
+	else if (arg1->ip_posid < arg2->ip_posid)
+		return -1;
+	else if (arg1->ip_posid > arg2->ip_posid)
+		return 1;
+	else
+		return 0;
+}
+
 Datum
 tideq(PG_FUNCTION_ARGS)
 {
 	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
 	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
 
-	PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) ==
-				   BlockIdGetBlockNumber(&(arg2->ip_blkid)) &&
-				   arg1->ip_posid == arg2->ip_posid);
+	PG_RETURN_BOOL(tid_cmp_internal(arg1,arg2) == 0);
 }
 
 Datum
@@ -180,11 +196,73 @@ tidne(PG_FUNCTION_ARGS)
 	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
 	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
 
-	PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) !=
-				   BlockIdGetBlockNumber(&(arg2->ip_blkid)) ||
-				   arg1->ip_posid != arg2->ip_posid);
+	PG_RETURN_BOOL(tid_cmp_internal(arg1,arg2) != 0);
 }
 
+Datum
+tidlt(PG_FUNCTION_ARGS)
+{
+	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
+	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
+
+	PG_RETURN_BOOL(tid_cmp_internal(arg1,arg2) < 0);
+}
+
+Datum
+tidle(PG_FUNCTION_ARGS)
+{
+	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
+	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
+
+	PG_RETURN_BOOL(tid_cmp_internal(arg1,arg2) <= 0);
+}
+
+Datum
+tidgt(PG_FUNCTION_ARGS)
+{
+	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
+	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
+
+	PG_RETURN_BOOL(tid_cmp_internal(arg1,arg2) > 0);
+}
+
+Datum
+tidge(PG_FUNCTION_ARGS)
+{
+	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
+	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
+
+	PG_RETURN_BOOL(tid_cmp_internal(arg1,arg2) >= 0);
+}
+
+Datum
+bttidcmp(PG_FUNCTION_ARGS)
+{
+	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
+	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
+
+	PG_RETURN_INT32(tid_cmp_internal(arg1, arg2));
+}
+
+Datum
+tidlarger(PG_FUNCTION_ARGS)
+{
+	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
+	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
+
+	PG_RETURN_ITEMPOINTER(tid_cmp_internal(arg1,arg2) >= 0 ? arg1 : arg2);
+}
+
+Datum
+tidsmaller(PG_FUNCTION_ARGS)
+{
+	ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
+	ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
+
+	PG_RETURN_ITEMPOINTER(tid_cmp_internal(arg1,arg2) <= 0 ? arg1 : arg2);
+}
+
+
 /*
  *	Functions to get latest tid of a specified tuple.
  *