On Tue, May 12, 2015 at 10:42 PM, Andrew Dunstan <andrew@dunslane.net> wrote:
> Map basebackup tablespaces using a tablespace_map file
>
> Windows can't reliably restore symbolic links from a tar format, so
> instead during backup start we create a tablespace_map file, which is
> used by the restoring postgres to create the correct links in pg_tblspc.
> The backup protocol also now has an option to request this file to be
> included in the backup stream, and this is used by pg_basebackup when
> operating in tar mode.
>
> This is done on all platforms, not just Windows.
>
> This means that pg_basebackup will not not work in tar mode against 9.4
> and older servers, as this protocol option isn't implemented there.
While I was performing the recovery-related tests, I found that there was
the case where $PGDATA/tablespace_map was not renamed to *.old at the recovery.
Is this harmless and intentional? Sorry if this has been already
discussed so far.
The steps to reproduce the problem is:
1. start base backup, i.e., call pg_start_backup().
2. repeat some write transactions and checkpoints until the WAL file containing the checkpoint record that
backup_labelindicates will be removed.
3. killall -9 postgres
4. start the server and a crash recovery.
At this time, the crash recovery fails with the following error messages.
2015-06-09 12:26:54 JST FATAL: could not locate required checkpoint record
2015-06-09 12:26:54 JST HINT: If you are not restoring from a backup,
try removing the file ".../backup_label".
5. according to the above hint message, remove $PGDATA/backup_label and restart a crash recovery
Then you can see that tablespace_map remains in $PGDATA after the recovery ends.
Regards,
--
Fujii Masao
