Re: Unhappy thoughts about pg_dump and objects inherited from template1

At 19:35 2/11/00 -0500, Tom Lane wrote:
>We've hacked up pg_dump so that it won't dump objects inherited from
>template1. Unfortunately I have realized there are a couple of serious
>problems:
>
>1. What if the inherited object is a table or a sequence?
>2. For that matter, even function definitions might change

The only solution I can think of for this would be to use lastsysoid from
template1; this is the value set when initdb runs.

>3. What if the OID counter wraps around?

Can the code that wraps the OID restart it at 'select max(lastsysoid) from
pg_database'? Is that too complex?

>Maybe we should give up the whole idea of user data
>in template1.

I'm leaning a little this way, but local mods are useful.

There's also a problem if a db drops a function created by template1, then
creates its own version (eg. via (mythical) ALTER FUNCTION). If we restore
template1 then the db, we get a problem.

Perhaps, for pg_dumpall:

1. Restore vanilla template1 (this is probably not necessary?)
2. Restore all DBs (dumped using template1->lastsysoid)
3. Restore local mods to template1

And for single-db dump we dump using db->lastsysoid (the assumption being
that the DB will be restored in the 'right' template1 context). This would
be the default behaviour of pg_dump.

This requires a way of asking pg_dump to use a 'system' (ie. template1) or
'local' (ie. from the specific database) lastsysoid...( --last-oid
{S,D}/-L{S,D}). I think this fixes it, but perhaps I'm hallucinating.

Does this sound OK?

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