lmgr.c:DescribeLockTag was never taught about virtual xids, per Greg Stark.

Also a couple of minor tweaks to try to future-proof the code a bit better
against future locktag additions.

src/backend/storage/lmgr/lmgr.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lmgr.c,v 1.95 2008/01/01 19:45:52 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/lmgr.c,v 1.96 2008/01/08 23:18:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -672,7 +672,7 @@ UnlockSharedObject(Oid classid, Oid objid, uint16 objsubid,
 bool
 LockTagIsTemp(const LOCKTAG *tag)
 {
-	switch (tag->locktag_type)
+	switch ((LockTagType) tag->locktag_type)
 	{
 		case LOCKTAG_RELATION:
 		case LOCKTAG_RELATION_EXTEND:
@@ -686,6 +686,7 @@ LockTagIsTemp(const LOCKTAG *tag)
 				return true;
 			break;
 		case LOCKTAG_TRANSACTION:
+		case LOCKTAG_VIRTUALTRANSACTION:
 			/* there are no temp transactions */
 			break;
 		case LOCKTAG_OBJECT:
@@ -710,7 +711,7 @@ LockTagIsTemp(const LOCKTAG *tag)
 void
 DescribeLockTag(StringInfo buf, const LOCKTAG *tag)
 {
-	switch (tag->locktag_type)
+	switch ((LockTagType) tag->locktag_type)
 	{
 		case LOCKTAG_RELATION:
 			appendStringInfo(buf,
@@ -744,6 +745,12 @@ DescribeLockTag(StringInfo buf, const LOCKTAG *tag)
 							 _("transaction %u"),
 							 tag->locktag_field1);
 			break;
+		case LOCKTAG_VIRTUALTRANSACTION:
+			appendStringInfo(buf,
+							 _("virtual transaction %d/%u"),
+							 tag->locktag_field1,
+							 tag->locktag_field2);
+			break;
 		case LOCKTAG_OBJECT:
 			appendStringInfo(buf,
 							 _("object %u of class %u of database %u"),
@@ -770,7 +777,7 @@ DescribeLockTag(StringInfo buf, const LOCKTAG *tag)
 		default:
 			appendStringInfo(buf,
 							 _("unrecognized locktag type %d"),
-							 tag->locktag_type);
+							 (int) tag->locktag_type);
 			break;
 	}
 }

src/backend/utils/adt/lockfuncs.c

@@ -6,7 +6,7 @@
  * Copyright (c) 2002-2008, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *		$PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.31 2008/01/01 19:45:52 momjian Exp $
+ *		$PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.32 2008/01/08 23:18:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -206,7 +206,7 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		MemSet(values, 0, sizeof(values));
 		MemSet(nulls, ' ', sizeof(nulls));
 
-		if (lock->tag.locktag_type <= LOCKTAG_ADVISORY)
+		if (lock->tag.locktag_type <= LOCKTAG_LAST_TYPE)
 			locktypename = LockTagTypeNames[lock->tag.locktag_type];
 		else
 		{
@@ -217,7 +217,7 @@ pg_lock_status(PG_FUNCTION_ARGS)
 		values[0] = DirectFunctionCall1(textin,
 										CStringGetDatum(locktypename));
 
-		switch (lock->tag.locktag_type)
+		switch ((LockTagType) lock->tag.locktag_type)
 		{
 			case LOCKTAG_RELATION:
 			case LOCKTAG_RELATION_EXTEND:

src/include/storage/lock.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.111 2008/01/01 19:45:59 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.112 2008/01/08 23:18:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -186,6 +186,8 @@ typedef enum LockTagType
 	LOCKTAG_ADVISORY			/* advisory user locks */
 } LockTagType;
 
+#define LOCKTAG_LAST_TYPE	LOCKTAG_ADVISORY
+
 /*
  * The LOCKTAG struct is defined with malice aforethought to fit into 16
  * bytes with no padding.  Note that this would need adjustment if we were