On 9/21/07, Tom Lane <[EMAIL PROTECTED]> wrote:
> but control never gets that far because neither xmin nor xmax is
> committed yet. We could fix that, probably, by considering the
> xmin=xmax case in the xmin-in-progress case further up; but the
> HEAP_UPDATED exclusion is still a problem. Still, it seems like this
> is leaving some money on the table when you think about pruning a HOT
> chain. Can we improve on it easily?
May be we can, but it would get a bit tricky. There might be a transaction
looking at the first tuple in the chain and waiting for this
transaction to finish. If the waiting transaction is running in READ
mode, it would then follow the update chain. Removing any intermediate
tuples without fixing the previous tuple's xmax/ctid (or redirected line
would be tricky.