Re: 32/64-bit transaction IDs?

"Ed L." <pgsql@bluepolka.net> writes:
>     create table pg_xlog (
>         xid        int4 unique not null,
>         recno    int8 unique not null,
>     );
>     -- recno = (XLogRecPtr.xlogid) << 32) + XLogRecPtr.xrecoff

> This would map transaction IDs to WAL log record numbers.  It seems
> straight-forward to get the right data into this table.

... except that once a transaction has committed, it can't go around
making more database entries.  You can only modify the DB within a
transaction.

            regards, tom lane