> Here is a first approximation of consistency rules:
>
> 1. A transaction sees a constant view of the database plus any
> updates performed by the transaction
> 2. A transaction cannot update or delete a version of a record that
> it could not see
> 3. Primary and unique keys must be guaranteed unique
> 4. Referential constraints must be honored
>
> What other elements of database consistency need to be maintained
> implicitly or explicitly?

Why only honour referential integrity? Don't you want to honour check
constraints, domain constraints, etc. ?? Perhaps 4. should read
"Constraints must be honoured"; 3. becomes superfluous then, as primary &
unique are constraints too.

2. is specific to MVCC and kinda overlaps with 1. Perhaps "sees" is wrong
and should be "has". On a point of language I would say "performed within
itself", but meaning the same thing.

Paul