Re: a few questions (and doubts) about xid

Thanks all for your comments. Just another little hint here (sorry for trivial
questions):

    if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
    {
        if (tuple->t_infomask & HEAP_IS_LOCKED)
            return true;
        if (HeapTupleHeaderGetCmax(tuple) >= GetCurrentCommandId())
            return true;        /* deleted after scan started */
        else
            return false;        /* deleted before scan started */
    }

what does that "deleted after scan started" means? How is possible that the
current transaction has deleted the tuple with a command higher than the one
that is still executing? An example could clearify....

Thanks,
Luca