Exporting large objects in 7.0.2

[Ross Johnson]

Hi,

I'm moving a database from 7.0.2 to 7.3.3. The db contains several thousand
large objects that I need to export.

To do this I've managed to modify the contrib/pg_dumplo utility from 7.3.3 so
that it works with 7.0.2, but I need to confirm a few things before I can be
confident that I can proceed.

When I run the modified pg_dumplo in 'show only' mode it reports about 8500
large object references across several tables. However, when I run it in export
mode, it produces about 5400 'lo_export: can't open inv object <oid value>'
messages.

I've looked at a few of these oid values and confirmed that there is indeed no
entry in pg_class with that value, or corresponding relname 'xinv<oid value>'.

So does this mean that I have oid value references that simply should not exist?

Can I be confident that if there is no entry in pg_class, that there is actually
no large object for that oid reference?

Thanks.
Ross Johnson
rp*@ise.canberra.edu.au
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[Tom Lane]

Ross Johnson <rp*@ise.canberra.edu.au> writes:

Can I be confident that if there is no entry in pg_class, that there
is actually no large object for that oid reference?

In 7.0, yes. Later versions keep large objects in pg_largeobject rather
than in individual tables. I don't recall the details of pg_dumplo, but
it's likely that it's confused by this difference.

You might try running the 7.3 pg_dump against the 7.0 server in one of
the modes that can dump large objects. Theoretically that should work,
though I can't say I've tried it recently.

regards, tom lane

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