On 04/29/2014 06:00 PM, Tom Lane wrote:
Andrew Dunstan <and...@dunslane.net> writes:
On 04/29/2014 02:56 AM, Heikki Linnakangas wrote:
On 04/28/2014 10:32 PM, Tom Lane wrote:
Meh. I still think it's a bad idea to have CATALOG_VERSION_NO getting
compiled into libpgcommon.a, where there will be no way to cross-check
that it matches anything. But I guess I'm losing this argument.
FWIW, I agree it's a bad idea. I just have no better ideas (and
haven't given it much thought anyway).
Sure sounds like a bad idea.
One idea would be to have relpath.h/.c expose a function (not a #define)
that returns the value of CATALOG_VERSION_NO compiled into it. Then,
if pg_rewind were to replace all its direct references to
CATALOG_VERSION_NO (including the value it checks against pg_control)
with calls of that function, consistency would be ensured.
In pg_rewind, I'd like to compile CATALOG_VERSION_NO into the binary
itself, because pg_rewind is quite version-specific. Even if it happens
to work with libpgport from a different version, I would worry that
there are directory layout changes that would need to be handled in
pg_rewind for it to work safely. So I would like to lock it to a
specific catalog version.
To lock it down, I could call the function and check that it matches the
compiled-in value of CATALOG_VERSION_NO, though. So a function works for
me, even though I don't really need the flexibility.
A notational problem is that if pg_rewind or similar program is directly
using the TABLESPACE_VERSION_DIRECTORY macro anywhere, this wouldn't
work. But we could perhaps expose a function to return that string too.
pg_rewind doesn't use TABLESPACE_VERSION_DIRECTORY directly.
- Heikki
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
