copy_status_flags_v3.patch

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 05221cc1d6..5fbeacc0da 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -4147,6 +4147,12 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	LVRelState	vacrel;
 	ErrorContextCallback errcallback;
 
+	/*
+	 * A parallel vacuum worker must have only PROC_IN_VACUUM flag since we
+	 * don't support parallel vacuum for autovacuum as of now.
+	 */
+	Assert(MyProc->statusFlags == PROC_IN_VACUUM);
+
 	lvshared = (LVShared *) shm_toc_lookup(toc, PARALLEL_VACUUM_KEY_SHARED,
 										   false);
 	elevel = lvshared->elevel;
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index 54c8eb1289..af562fcfae 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -1808,6 +1808,13 @@ _bt_parallel_build_main(dsm_segment *seg, shm_toc *toc)
 		ResetUsage();
 #endif							/* BTREE_BUILD_STATS */
 
+	/*
+	 * A possible status flag that can be set to the parallel worker is
+	 * only PROC_IN_SAFE_IC.
+	 */
+	Assert((MyProc->statusFlags == 0) ||
+		   (MyProc->statusFlags == PROC_IN_SAFE_IC));
+
 	/* Set debug_query_string for individual workers first */
 	sharedquery = shm_toc_lookup(toc, PARALLEL_KEY_QUERY_TEXT, true);
 	debug_query_string = sharedquery;
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index bd3c7a47fe..64fa2db471 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2636,7 +2636,8 @@ ProcArrayInstallImportedXmin(TransactionId xmin,
  *
  * This is like ProcArrayInstallImportedXmin, but we have a pointer to the
  * PGPROC of the transaction from which we imported the snapshot, rather than
- * an XID.
+ * an XID.  Also, this copies statusFlags from source xact so as not to affect
+ * OldestXmin in case of parallel workers for vacuum etc.
  *
  * Returns true if successful, false if source xact is no longer running.
  */
@@ -2645,6 +2646,7 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc)
 {
 	bool		result = false;
 	TransactionId xid;
+	uint8		flags;
 
 	Assert(TransactionIdIsNormal(xmin));
 	Assert(proc != NULL);
@@ -2652,6 +2654,18 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc)
 	/* Get lock so source xact can't end while we're doing this */
 	LWLockAcquire(ProcArrayLock, LW_SHARED);
 
+	flags = proc->statusFlags;
+
+	/*
+	 * If the source xact has any statusFlags, we re-grab ProcArrayLock
+	 * on exclusive mode so we can copy it to MyProc->statusFlags.
+	 */
+	if (flags != 0)
+	{
+		LWLockRelease(ProcArrayLock);
+		LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
+	}
+
 	/*
 	 * Be certain that the referenced PGPROC has an advertised xmin which is
 	 * no later than the one we're installing, so that the system-wide xmin
@@ -2663,7 +2677,16 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc)
 		TransactionIdIsNormal(xid) &&
 		TransactionIdPrecedesOrEquals(xid, xmin))
 	{
+		/* restore xmin */
 		MyProc->xmin = TransactionXmin = xmin;
+
+		/* copy statusFlags */
+		if (flags != 0)
+		{
+			MyProc->statusFlags = proc->statusFlags;
+			ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
+		}
+
 		result = true;
 	}