Subject Re: [IB-Architect] Super-transactions and Incremental Backup
Author Jim Starkey
At 05:30 PM 6/20/00 -0400, Doug Chamberlin wrote:
>At 6/20/00 03:59 PM (Tuesday), Jim Starkey wrote:
>>Unless the super-transaction that defines a freeze point performs updates,
>>the newest pre-freeze point record versions and the at-freeze point record
>>versions are one and the same.
>Agreed. I guess we are referring to the same records with different labels.
>I don't see the super transaction that establishes the freeze point doing
>anything other than work directly required to establish the freeze point. A
>possible exception would be rebuilding the current records so they are all
>full records without reference to those versions before or after. That
>would free the garbage collector to not have to do this at another time and
>thus complicating it further.

The head record is always a full record and by definition doesn't have
a new version.

But let me repeat my question. Why do you need to preserve the
records at the "freeze point"? Assuming the rest of the problems
have solutions, the records that exist at the freeze points are the
only records you don't need to produce an incremental backup. What
is the gain in trying to preserve them?

Jim Starkey