WIP-horizon-stuff.diff

diff --git i/src/backend/commands/vacuum.c w/src/backend/commands/vacuum.c
index ddeec870d81..8851fafed64 100644
--- i/src/backend/commands/vacuum.c
+++ w/src/backend/commands/vacuum.c
@@ -950,24 +950,8 @@ vacuum_set_xid_limits(Relation rel,
 	MultiXactId mxactLimit;
 	MultiXactId safeMxactLimit;
 
-	if (RELATION_IS_LOCAL(rel) && !IsInTransactionBlock(isTopLevel))
 	{
 		/*
-		 * If we are processing a temp relation (which by prior checks must be
-		 * one belonging to our session), and we are not inside any
-		 * transaction block, then there can be no tuples in the rel that are
-		 * still in-doubt, nor can there be any that are dead but possibly
-		 * still interesting to some snapshot our session holds.  We don't
-		 * need to care whether other sessions could see such tuples, either.
-		 * So we can aggressively set the cutoff xmin to be the nextXid.
-		 */
-		*oldestXmin = ReadNewTransactionId();
-	}
-	else
-	{
-		/*
-		 * Otherwise, calculate the cutoff xmin normally.
-		 *
 		 * We can always ignore processes running lazy vacuum.  This is
 		 * because we use these values only for deciding which tuples we must
 		 * keep in the tables.  Since lazy vacuum doesn't write its XID
diff --git i/src/backend/storage/ipc/procarray.c w/src/backend/storage/ipc/procarray.c
index 07c5eeb7495..c3cfe34ffee 100644
--- i/src/backend/storage/ipc/procarray.c
+++ w/src/backend/storage/ipc/procarray.c
@@ -153,6 +153,8 @@ typedef struct ProcArrayStruct
  *    I.e. the difference to GlobalVisCatalogRels is that
  *    replication slot's catalog_xmin is not taken into account.
  *
+ * 4) GlobalVisTempRels, XXXX
+ *
  * GlobalVisTestFor(relation) returns the appropriate state
  * for the relation.
  *
@@ -234,6 +236,9 @@ typedef struct ComputeXidHorizonsResult
 	 * defined tables.
 	 */
 	TransactionId data_oldest_nonremovable;
+
+	TransactionId temp_oldest_nonremovable;
+
 } ComputeXidHorizonsResult;
 
 
@@ -257,12 +262,13 @@ static TransactionId standbySnapshotPendingXmin;
 
 /*
  * State for visibility checks on different types of relations. See struct
- * GlobalVisState for details. As shared, catalog, and user defined
+ * GlobalVisState for details. As shared, catalog, normal and temporary
  * relations can have different horizons, one such state exists for each.
  */
 static GlobalVisState GlobalVisSharedRels;
 static GlobalVisState GlobalVisCatalogRels;
 static GlobalVisState GlobalVisDataRels;
+static GlobalVisState GlobalVisTempRels;
 
 /*
  * This backend's RecentXmin at the last time the accurate xmin horizon was
@@ -1668,6 +1674,10 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
 		h->oldest_considered_running = initial;
 		h->shared_oldest_nonremovable = initial;
 		h->data_oldest_nonremovable = initial;
+		if (TransactionIdIsValid(MyProc->xid))
+			h->temp_oldest_nonremovable = MyProc->xid;
+		else
+			h->temp_oldest_nonremovable = initial;
 	}
 
 	/*
@@ -1760,6 +1770,7 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
 			TransactionIdOlder(h->shared_oldest_nonremovable, kaxmin);
 		h->data_oldest_nonremovable =
 			TransactionIdOlder(h->data_oldest_nonremovable, kaxmin);
+		/* temp relations cannot be accessed in recovery */
 	}
 	else
 	{
@@ -1785,6 +1796,7 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
 		h->data_oldest_nonremovable =
 			TransactionIdRetreatedBy(h->data_oldest_nonremovable,
 									 vacuum_defer_cleanup_age);
+		/* defer doesn't apply to temp relations */
 	}
 
 	/*
@@ -1844,6 +1856,8 @@ ComputeXidHorizons(ComputeXidHorizonsResult *h)
 										 h->catalog_oldest_nonremovable));
 	Assert(TransactionIdPrecedesOrEquals(h->oldest_considered_running,
 										 h->data_oldest_nonremovable));
+	Assert(TransactionIdPrecedesOrEquals(h->oldest_considered_running,
+										 h->temp_oldest_nonremovable));
 	Assert(!TransactionIdIsValid(h->slot_xmin) ||
 		   TransactionIdPrecedesOrEquals(h->oldest_considered_running,
 										 h->slot_xmin));
@@ -1878,6 +1892,8 @@ GetOldestNonRemovableTransactionId(Relation rel)
 		return horizons.shared_oldest_nonremovable;
 	else if (RelationIsAccessibleInLogicalDecoding(rel))
 		return horizons.catalog_oldest_nonremovable;
+	else if (RELATION_IS_LOCAL(rel))
+		return horizons.temp_oldest_nonremovable;
 	else
 		return horizons.data_oldest_nonremovable;
 }
@@ -2357,6 +2373,9 @@ GetSnapshotData(Snapshot snapshot)
 		GlobalVisDataRels.definitely_needed =
 			FullTransactionIdNewer(def_vis_fxid_data,
 								   GlobalVisDataRels.definitely_needed);
+		GlobalVisTempRels.definitely_needed =
+			FullTransactionIdNewer(latest_completed,
+								   GlobalVisTempRels.definitely_needed);
 
 		/*
 		 * Check if we know that we can initialize or increase the lower
@@ -2375,6 +2394,18 @@ GetSnapshotData(Snapshot snapshot)
 		GlobalVisDataRels.maybe_needed =
 			FullTransactionIdNewer(GlobalVisDataRels.maybe_needed,
 								   oldestfxid);
+		if (TransactionIdIsNormal(myxid))
+		{
+			GlobalVisTempRels.maybe_needed =
+				FullTransactionIdNewer(GlobalVisTempRels.maybe_needed,
+									   FullXidRelativeTo(latest_completed, myxid));
+		}
+		else
+		{
+			GlobalVisTempRels.maybe_needed =
+				FullTransactionIdNewer(GlobalVisTempRels.maybe_needed,
+									   latest_completed);
+		}
 	}
 
 	RecentXmin = xmin;
@@ -3892,6 +3923,8 @@ GlobalVisTestFor(Relation rel)
 		state = &GlobalVisSharedRels;
 	else if (need_catalog)
 		state = &GlobalVisCatalogRels;
+	else if (RELATION_IS_LOCAL(rel))
+		state = &GlobalVisTempRels;
 	else
 		state = &GlobalVisDataRels;
 
@@ -3942,6 +3975,9 @@ GlobalVisUpdateApply(ComputeXidHorizonsResult *horizons)
 	GlobalVisDataRels.maybe_needed =
 		FullXidRelativeTo(horizons->latest_completed,
 						  horizons->data_oldest_nonremovable);
+	GlobalVisTempRels.maybe_needed =
+		FullXidRelativeTo(horizons->latest_completed,
+						  horizons->temp_oldest_nonremovable);
 
 	/*
 	 * In longer running transactions it's possible that transactions we
@@ -3957,6 +3993,9 @@ GlobalVisUpdateApply(ComputeXidHorizonsResult *horizons)
 	GlobalVisDataRels.definitely_needed =
 		FullTransactionIdNewer(GlobalVisDataRels.maybe_needed,
 							   GlobalVisDataRels.definitely_needed);
+	GlobalVisTempRels.definitely_needed =
+		FullTransactionIdNewer(GlobalVisTempRels.maybe_needed,
+							   GlobalVisTempRels.definitely_needed);
 
 	ComputeXidHorizonsResultLastXmin = RecentXmin;
 }
diff --git i/contrib/pg_surgery/Makefile w/contrib/pg_surgery/Makefile
index a66776c4c41..48a96008cea 100644
--- i/contrib/pg_surgery/Makefile
+++ w/contrib/pg_surgery/Makefile
@@ -9,7 +9,7 @@ EXTENSION = pg_surgery
 DATA = pg_surgery--1.0.sql
 PGFILEDESC = "pg_surgery - perform surgery on a damaged relation"
 
-REGRESS = heap_surgery
+REGRESS = --schedule=$(srcdir)/surgery_schedule
 
 ifdef USE_PGXS
 PG_CONFIG = pg_config
diff --git i/contrib/pg_surgery/expected/heap_surgery.out w/contrib/pg_surgery/expected/heap_surgery.out
index d4a757ffa01..6ef5597e7cc 100644
--- i/contrib/pg_surgery/expected/heap_surgery.out
+++ w/contrib/pg_surgery/expected/heap_surgery.out
@@ -1,4 +1,10 @@
 create extension pg_surgery;
+select pg_sleep(0.1);  -- ensure concurrent transaction is ready
+ pg_sleep 
+----------
+ 
+(1 row)
+
 -- create a normal heap table and insert some rows.
 -- use a temp table so that vacuum behavior doesn't depend on global xmin
 create temp table htab (a int);
diff --git i/contrib/pg_surgery/sql/heap_surgery.sql w/contrib/pg_surgery/sql/heap_surgery.sql
index 6526b27535d..212c657f3c7 100644
--- i/contrib/pg_surgery/sql/heap_surgery.sql
+++ w/contrib/pg_surgery/sql/heap_surgery.sql
@@ -1,5 +1,7 @@
 create extension pg_surgery;
 
+select pg_sleep(0.1);  -- ensure concurrent transaction is ready
+
 -- create a normal heap table and insert some rows.
 -- use a temp table so that vacuum behavior doesn't depend on global xmin
 create temp table htab (a int);