Re: Catalog/Metadata consistency during changeset extraction from wal

On Thursday, June 21, 2012 05:05:04 PM Simon Riggs wrote:
> On 21 June 2012 15:53, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> >> ISTM we should maintain a lookup table on target system that has the
> >> minimal required information on it.
> >
> > You need just about the whole catalog because the *_out procs might need
> > to lookup types, operators and such again.
> > Unless you want to rewrite those functions you need to provide a normal
> > execution environment.
>
> OK, so its more tables than I first thought, but its not all rows and
> columns of all catalog tables.
Sure, there are a few you probably can leave out (pg_database, pg_auth*,
pg_*acl, pg_(sh)?depend, pg_database, pg_tablespace, ...) but its not many.

> > I don't see how your idea works because of that? Am I missing something?
> Why does the number/size of the tables required make that not work?
The number of tables itself isn't a fundamental problem although it would make
stuff harder.
The problem is that the out functions expect a normal operating environment
and might e.g. do catalog lookups themselves. I don't see how we can do
anything here without providing a (nearly) full catalog.

Greetings,

Andres
--
Andres Freund http://www.2ndQuadrant.com/
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