On Tue, Sep 25, 2012 at 4:07 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Brian Weaver <cmdrcluel...@gmail.com> writes: >> While researching the way streaming replication works I was examining >> the construction of the tar file header. By comparing documentation on >> the tar header format from various sources I certain the following >> patch should be applied to so the group identifier is put into thee >> header properly. > > Yeah, this is definitely wrong. > >> While I realize that wikipedia isn't always the best source of >> information, the header offsets seem to match the other documentation >> I've found. The format is just easier to read on wikipedia > > The authoritative specification can be found in the "pax" page in the > POSIX spec, which is available here: > http://pubs.opengroup.org/onlinepubs/9699919799/ > > I agree that the 117 number is bogus, and also that the magic "ustar" > string is written incorrectly. What's more, it appears that the latter > error has been copied from pg_dump (but the 117 seems to be just a new > bug in pg_basebackup). I wonder what else might be wrong hereabouts :-( > Will sit down and take a closer look. > > I believe what we need to do about this is: > > 1. fix pg_dump and pg_basebackup output to conform to spec. > > 2. make sure pg_restore will accept both conformant and > previous-generation files. > > Am I right in believing that we don't have any code that's expected to > read pg_basebackup output? We just feed it to "tar", no?
Yes. We generate a .tarfile, but we have no tool that reads it ourselves. (unlike pg_dump where we have pg_restore that actually reads it) > I'm a bit concerned about backwards compatibility issues. It looks to > me like existing versions of pg_restore will flat out reject files that > have a spec-compliant "ustar\0" MAGIC field. Is it going to be > sufficient if we fix this in minor-version updates, or are we going to > need to have a switch that tells pg_dump to emit the incorrect old > format? (Ick.) Do we officially support using an older pg_restore to reload a newer dump? I think not? As long as we don't officially support that, I think we'll be ok. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
