diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index abc5682..ce079cf 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7783,7 +7783,8 @@ LogCheckpointStart(int flags, bool restartpoint)
 		 (flags & CHECKPOINT_FORCE) ? " force" : "",
 		 (flags & CHECKPOINT_WAIT) ? " wait" : "",
 		 (flags & CHECKPOINT_CAUSE_XLOG) ? " xlog" : "",
-		 (flags & CHECKPOINT_CAUSE_TIME) ? " time" : "");
+		 (flags & CHECKPOINT_CAUSE_TIME) ? " time" : "",
+		 (flags & CHECKPOINT_FLUSH_ALL) ? " flush-all" :"");
 }
 
 /*
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 5705889..3e2afee 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1122,8 +1122,13 @@ movedb(const char *dbname, const char *tblspcname)
 	 * that the copy might fail due to source files getting deleted under it.
 	 * On Windows, this also ensures that background procs don't hold any open
 	 * files, which would cause rmdir() to fail.
+	 *
+	 * We must also force all dirty buffers belonging to unlogged relations out
+	 * to the disk before making any file system changes.  Otherwise a backend
+	 * may fail if the buffer is chosen for eviction or at shutdown checkpoint
+	 * which writes all dirty buffers to the disk.
 	 */
-	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
+	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT | CHECKPOINT_FLUSH_ALL);
 
 	/*
 	 * Check for existence of files in the target directory, i.e., objects of
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 07ea665..c66b27d 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1205,9 +1205,10 @@ UnpinBuffer(volatile BufferDesc *buf, bool fixOwner)
  *
  * This is called at checkpoint time to write out all dirty shared buffers.
  * The checkpoint request flags should be passed in.  If CHECKPOINT_IMMEDIATE
- * is set, we disable delays between writes; if CHECKPOINT_IS_SHUTDOWN is
- * set, we write even unlogged buffers, which are otherwise skipped.  The
- * remaining flags currently have no effect here.
+ * is set, we disable delays between writes; if CHECKPOINT_IS_SHUTDOWN,
+ * CHECKPOINT_END_OF_RECOVERY or CHECKPOINT_FLUSH_ALL is set, we write even
+ * unlogged buffers, which are otherwise skipped.  The remaining flags
+ * currently have no effect here.
  */
 static void
 BufferSync(int flags)
@@ -1222,11 +1223,13 @@ BufferSync(int flags)
 	ResourceOwnerEnlargeBuffers(CurrentResourceOwner);
 
 	/*
-	 * Unless this is a shutdown checkpoint, we write only permanent, dirty
-	 * buffers.  But at shutdown or end of recovery, we write all dirty
-	 * buffers.
+	 * Unless this is a shutdown checkpoint or we have been explicitly told,
+	 * we write only permanent, dirty buffers.  But at shutdown or end of
+	 * recovery, we write all dirty buffers.
 	 */
-	if (!((flags & CHECKPOINT_IS_SHUTDOWN) || (flags & CHECKPOINT_END_OF_RECOVERY)))
+	if (!((flags & CHECKPOINT_IS_SHUTDOWN) ||
+		  (flags & CHECKPOINT_END_OF_RECOVERY) ||
+		  (flags & CHECKPOINT_FLUSH_ALL)))
 		mask |= BM_PERMANENT;
 
 	/*
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 85f9cb7..c5ac599 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -247,12 +247,13 @@ extern bool XLOG_DEBUG;
 												 * recovery */
 #define CHECKPOINT_IMMEDIATE	0x0004	/* Do it without delays */
 #define CHECKPOINT_FORCE		0x0008	/* Force even if no activity */
+#define CHECKPOINT_FLUSH_ALL	0x0010	/* Flush all pages, including those
+										 * belonging to unlogged tables */
 /* These are important to RequestCheckpoint */
-#define CHECKPOINT_WAIT			0x0010	/* Wait for completion */
+#define CHECKPOINT_WAIT			0x0020	/* Wait for completion */
 /* These indicate the cause of a checkpoint request */
-#define CHECKPOINT_CAUSE_XLOG	0x0020	/* XLOG consumption */
-#define CHECKPOINT_CAUSE_TIME	0x0040	/* Elapsed time */
-
+#define CHECKPOINT_CAUSE_XLOG	0x0040	/* XLOG consumption */
+#define CHECKPOINT_CAUSE_TIME	0x0080	/* Elapsed time */
 /* Checkpoint statistics */
 typedef struct CheckpointStatsData
 {