Ensure that creation of an empty relfile is fsync'd at checkpoint.

hlinnaka · hlinnaka · commit 4b4798e1384c · 2023-07-04T17:57:03.000+03:00
If you create a table and don't insert any data into it, the relation file is never fsync'd. You don't lose data, because an empty table doesn't have any data to begin with, but if you crash and lose the file, subsequent operations on the table will fail with "could not open file" error. To fix, register an fsync request in mdcreate(), like we do for mdwrite(). Per discussion, we probably should also fsync the containing directory after creating a new file. But that's a separate and much wider issue. Backpatch to all supported versions. Reviewed-by: Andres Freund, Thomas Munro Discussion: https://www.postgresql.org/message-id/d47d8122-415e-425c-d0a2-e0160829702d%40iki.fi
diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
@@ -239,6 +239,9 @@ mdcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo)
 	mdfd = &reln->md_seg_fds[forknum][0];
 	mdfd->mdfd_vfd = fd;
 	mdfd->mdfd_segno = 0;
+
+	if (!SmgrIsTemp(reln))
+		register_dirty_segment(reln, forknum, mdfd);
 }
 
 /*

Original file line number	Diff line number	Diff line change
`@@ -239,6 +239,9 @@ mdcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo)`
`239`	`239`	`mdfd = &reln->md_seg_fds[forknum][0];`
`240`	`240`	`mdfd->mdfd_vfd = fd;`
`241`	`241`	`mdfd->mdfd_segno = 0;`
	`242`	`+`
	`243`	`+ if (!SmgrIsTemp(reln))`
	`244`	`+ register_dirty_segment(reln, forknum, mdfd);`
`242`	`245`	`}`
`243`	`246`
`244`	`247`	`/*`