Hi, So I am a bit confused about the status of the tar format support, and after re-reading the thread (or at least grepping it for ' tar '), this wasn't really much discussed here either.
On Wed, Jun 14, 2023 at 02:46:48PM -0400, Robert Haas wrote: > - We only know how to operate on directories, not tar files. I thought > about that when working on pg_verifybackup as well, but I didn't do > anything about it. It would be nice to go back and make that tool work > on tar-format backups, and this one, too. I believe "that tool" is pg_verifybackup, while "this one" is pg_combinebackup? However, what's up with pg_basebackup itself with respect to tar format incremental backups? AFAICT (see below), pg_basebackup -Ft --incremental=foo/backup_manifest happily creates an incremental backup in tar format; however, pg_combinebackup will not be able to restore it? If that is the case, shouldn't there be a bigger warning in the documentation about this, or maybe pg_basebackup should refuse to make incremental tar-format backups in the first place? Am I missing something here? It will be obvious to users after the first failure (to try to restore) that this will not work, and hopefully everybody tests a restore before they put a backup solution into production (or even better, wait until this whole feature is included in a wholesale solution), but I wonder whether somebody might trip over this after all and be unhappy. If one reads the pg_combinebackup documentation carefully it kinda becomes obvious that it does occupy itself with tar format backups, but it is not spelt out explicitly either. |postgres@mbanck-lin-1:~$ pg_basebackup -c fast -Ft -D backup/backup_full |postgres@mbanck-lin-1:~$ pg_basebackup -c fast -Ft -D backup/backup_incr_1 --incremental=backup/backup_full/backup_manifest |postgres@mbanck-lin-1:~$ echo $? |0 |postgres@mbanck-lin-1:~$ du -h backup/ |44M backup/backup_incr_1 |4,5G backup/backup_full |4,5G backup/ |postgres@mbanck-lin-1:~$ tar tf backup/backup_incr_1/base.tar | grep INCR | head |base/1/INCREMENTAL.3603 |base/1/INCREMENTAL.2187 |base/1/INCREMENTAL.13418 |base/1/INCREMENTAL.3467 |base/1/INCREMENTAL.2615_vm |base/1/INCREMENTAL.2228 |base/1/INCREMENTAL.3503 |base/1/INCREMENTAL.2659 |base/1/INCREMENTAL.2607_vm |base/1/INCREMENTAL.4164 |postgres@mbanck-lin-1:~$ /usr/lib/postgresql/17/bin/pg_combinebackup backup/backup_full/ backup/backup_incr_1/ -o backup/combined |pg_combinebackup: error: could not open file "backup/backup_incr_1//PG_VERSION": No such file or directory Michael
