Re: Upgrading rant.

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > OK, taking up the pg_upgrade banner, I think there are two things
> > missing from the current code:
>
> > 1) schema awareness -- easily fixed with some code
> > 2) need to creat clog files to match incremented xid
>
> > I can do 1, and I think Tom can help me with 2.
>
> I was just now wondering whether we really need to do that at all.
> We're already vacuuming the user tables before we bring 'em over.
> What if we VACUUM FREEZE them instead? Then there are *no* xids of
> interest in the tables being brought over, and no need to screw around
> with the xid counter in the new installation. That in turn would mean
> no need to mess with its pg_clog files. I think we'd still need to
> advance the xlog position past the old installation's xlog end, but we
> have the tool for that (pg_resetxlog) already.

VACUUM FREEZE. Interesting idea. Did we have that in 7.2? I never
thought of using it. Good idea.

Why do we have to do WAL? Do we have WAL log id's in the tuple headers?
I don't remember. I don't see them in a quick look.

> > Also, I think we make index format changes more frequently that Tom
> > recollects. Tom?
>
> Oh? Name one... not that they'd be a critical problem anyway, as we
> could easily reconstruct indexes via REINDEX rather than moving them
> over, any time we made such a change.

I remember fixing index problems, and asking folks to rebuild indexes
_after_ we fixed them, so I thought they had a new format. I guess they
were just broken indexes that had to be rebuilt to get the fix.

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