Re: pg_basebackup stream xlog to tar

On Sun, Oct 23, 2016 at 10:28 PM, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> It also broke the tests and invalidated some documentation. But it was easy
> enough to fix.
>
> I've now applied this, so next time you get to do the merging :P Joking
> aside, please review and let me know if you can spot something I messed up
> in the final merge.

Just had another look at it..
+static int
+tar_fsync(Walfile f)
+{
+ Assert(f != NULL);
+ tar_clear_error();
+
+ /*
+ * Always sync the whole tarfile, because that's all we can do. This makes
+ * no sense on compressed files, so just ignore those.
+ */
+ if (tar_data->compression)
+ return 0;
+
+ return fsync(tar_data->fd);
+}
fsync() should not be called here if --no-sync is used.

+ /* sync the empty blocks as well, since they're after the last file */
+ fsync(tar_data->fd);
Similarly, the fsync call of tar_finish() should not happen when
--no-sync is used.

+ if (format == 'p')
+ stream.walmethod = CreateWalDirectoryMethod(param->xlog, do_sync);
+ else
+ stream.walmethod = CreateWalTarMethod(param->xlog,
compresslevel, do_sync);
LogStreamerMain() exits immediately once it is done, but I think that
we had better be tidy here and clean up the WAL methods that have been
allocated. I am thinking here about a potentially retry method on
failure, though the best shot in this area would be with
ReceiveXlogStream().

Attached is a patch addressing those points.
--
Michael