Re: Exposing the Xact commit order to the user

On 5/23/2010 4:48 PM, Greg Sabino Mullane wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: RIPEMD160
>
>
>> Exposing the data will be done via a set returning function. The SRF
>> takes two arguments. The maximum number of rows to return and the last
>> serial number processed by the reader. The advantage of such SRF is that
>> the result can be used in a query that right away delivers audit or
>> replication log information in transaction commit order. The SRF can
>> return an empty set if no further transactions have committed since, or
>> an error if data segments needed to answer the request have already been
>> purged.
>
> In light of the proposed purging scheme, how would it be able to distinguish
> between those two cases (nothing there yet vs. was there but purged)?

There is a difference between an empty result set and an exception.

Jan

--
Anyone who trades liberty for security deserves neither
liberty nor security. -- Benjamin Franklin