On 04/28/2014 03:29 PM, Christoph Berg wrote:
Re: Heikki Linnakangas 2014-04-28 <535e09b7.3090...@vmware.com>
Comments? If there's anyone who has a really good use-case for using
relpath() from outside the backend, better speak up.
I'm using it in the pg_rewind tool. It needs to know how to map relfilenodes
to physical files.
It has quite intimate knowledge of the on-disk layout anyway, so it wouldn't
be the end of the world to just copy-paste that code. But would rather not,
of course.
Isn't pg_rewind so low-level server-close that it needs tons of server
headers anyway, including one that would still have relpath()? We are
talking here about what headers pure client apps need.
It knows how to decode WAL, similar to pg_xlogdump. And it knows about
the data directory layout, in particular, how relfilenodes are mapped to
physical files. Those are the low-level parts. So, it certainly needs
some server headers, but I wouldn't call it tons.
- Heikki
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