Re: erroneous restore into pg_catalog schema

Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> On 2013-05-13 14:48:52 -0400, Tom Lane wrote:
>> Andres Freund <andres(at)2ndquadrant(dot)com> writes:
>>> DROPing and recreating a new index in --single mode isn't that
>>> uncommon...

>> Surely you'd just REINDEX it instead. Moreover, if it isn't a system
>> index already, why are you doing this in --single mode at all?

> The last case I had was that an index was corrupted in a way that
> autovacuum got stuck on the corrupt index and wasn't killable. Without
> single mode it was hard to be fast enough to drop the index before
> autovac grabbed the lock again.

Meh. Actually, after looking closer at xlog.c, the OID counter starts
out at FirstBootstrapObjectId, which is not what I'd been thinking.
So a value less than that must indicate wraparound, which presumably
never happens during initdb. We could just change the code to

if (ShmemVariableCache->nextOid < ((Oid) FirstBootstrapObjectId))
{
/* wraparound while in standalone environment */
ShmemVariableCache->nextOid = FirstNormalObjectId;
ShmemVariableCache->oidCount = 0;
}

which is a bit asymmetric-looking but should do the right thing in all
cases.

regards, tom lane