Re: CREATE INDEX and HOT - revised design

"Simon Riggs" <simon@2ndquadrant.com> writes:
> There is a slight hole in that SERIALIZABLE transactions won't be able
> to use any indexes they build during their transaction, since they may
> need to be able to see prior data, but I don't think anybody is going to
> complain about that restriction. Anyone?

Practically every statement I've seen in this thread that used the
phrase "SERIALIZABLE transaction" was wrong to some extent, and this
one is no different.

The issue is not whether the whole transaction is serializable or not,
it's how old is the oldest still-live snapshot, a thing that CREATE
INDEX can't tell with any certainty in READ COMMITTED mode.  So if your
solution involves any explicit dependence on the transaction
serializability mode, it's probably wrong.  I'm not totally sure if you
are expecting to be able to tell that, but I do know that the planner
has no idea what snapshots a plan it makes will be used with.
        regards, tom lane