Greetings, When pg_upgrade calls pg_dump, it passes in "--schema-only", which is generally correct, except that this causes everything having to do with large objects to be excluded. That's still usually correct, because pg_upgrade will simply copy the pg_largeobject and pg_largeobject_metadata tables through to the new cluster as-is (essentially treating them as if they were user tables).
Unfortunately, those tables aren't, actually, the only places that we store information about large objects; the general-purpose tables like pg_seclabel and pg_description can hold information about large objects too. What this means is that performing a pg_upgrade will result in any security labels or comments on large objects being dropped. This seems to go back at least as far as 9.2, though I found it through the pg_dump regression testing that I've been working on. I haven't looked at trying to fix this yet, but I'm thinking the approach to use will probably be to modify pg_dump to still call getBlobs() when in binary-upgrade mode (regardless of the schema-only flag) but then have dumpBlobs(), when in binary-upgrade mode, only output the security labels and comments. I hope that doesn't end up causing some kind of chicken-and-egg problem.. Presumably the large object tables are in place and correct before the dump is restored, so I think this will work. Just wanted to get a note out to -hackers about the issue, I'll see about getting a fix written up for it soon. Thanks! Stephen
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