visible_debug.patch

--- backend/commands/vacuumlazy.c	2011-01-27 20:21:31.000000000 -0600
+++ ../../postgresql-9.0.3/src/backend/commands/vacuumlazy.c	2011-03-03 08:55:08.000000000 -0600
@@ -349,6 +349,7 @@ lazy_scan_heap(Relation onerel, LVRelSta
 		Size		freespace;
 		bool		all_visible_according_to_vm = false;
 		bool		all_visible;
+		char		*reason;
 
 		/*
 		 * Skip pages that don't require vacuuming according to the visibility
@@ -500,6 +501,7 @@ lazy_scan_heap(Relation onerel, LVRelSta
 		 * requiring freezing.
 		 */
 		all_visible = true;
+        reason = "";
 		nfrozen = 0;
 		hastup = false;
 		prev_dead_count = vacrelstats->num_dead_tuples;
@@ -538,6 +540,7 @@ lazy_scan_heap(Relation onerel, LVRelSta
 			{
 				lazy_record_dead_tuple(vacrelstats, &(tuple.t_self));
 				all_visible = false;
+				reason = "dead item";
 				continue;
 			}
 
@@ -573,6 +576,7 @@ lazy_scan_heap(Relation onerel, LVRelSta
 					else
 						tupgone = true; /* we can delete the tuple */
 					all_visible = false;
+					reason = "dead heaptuple";
 					break;
 				case HEAPTUPLE_LIVE:
 					/* Tuple is good --- but let's do some validity checks */
@@ -597,6 +601,7 @@ lazy_scan_heap(Relation onerel, LVRelSta
 						if (!(tuple.t_data->t_infomask & HEAP_XMIN_COMMITTED))
 						{
 							all_visible = false;
+							reason = "!HEAP_XMIN_COMMITTED";
 							break;
 						}
 
@@ -608,6 +613,7 @@ lazy_scan_heap(Relation onerel, LVRelSta
 						if (!TransactionIdPrecedes(xmin, OldestXmin))
 						{
 							all_visible = false;
+							reason = "OldestXmin";
 							break;
 						}
 					}
@@ -620,14 +626,17 @@ lazy_scan_heap(Relation onerel, LVRelSta
 					 */
 					nkeep += 1;
 					all_visible = false;
+					reason = "RecentlyDead";
 					break;
 				case HEAPTUPLE_INSERT_IN_PROGRESS:
 					/* This is an expected case during concurrent vacuum */
 					all_visible = false;
+					reason = "InsertInProgress";
 					break;
 				case HEAPTUPLE_DELETE_IN_PROGRESS:
 					/* This is an expected case during concurrent vacuum */
 					all_visible = false;
+					reason = "DeleteInProgress";
 					break;
 				default:
 					elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
@@ -705,8 +714,8 @@ lazy_scan_heap(Relation onerel, LVRelSta
 		}
 		else if (PageIsAllVisible(page) && !all_visible)
 		{
-			elog(WARNING, "PD_ALL_VISIBLE flag was incorrectly set in relation \"%s\" page %u",
-				 relname, blkno);
+			elog(WARNING, "PD_ALL_VISIBLE flag was incorrectly set in relation \"%s\" page %u via %s",
+				 relname, blkno, reason);
 			PageClearAllVisible(page);
 			SetBufferCommitInfoNeedsSave(buf);