Subject Re: [IB-Architect] Super-transactions and Incremental Backup
Author Jim Starkey
At 03:08 PM 6/20/00 -0400, Doug Chamberlin wrote:
>At 6/20/00 12:11 PM (Tuesday), Jim Starkey wrote:
>>Question 2: Garbage Collection
>>I gather that the idea is to retain the newest pre-freeze point version of
>>a record during garbage collection.
>Most everything else Jim has describes reflects my understanding of Jason's
>idea. However, the above statement (and every question which derives from
>it) does not. I thought the idea was to retain all the at-freeze-point
>records and the newest post-freeze-point records with any necessary garbage
>collection allowed between them and pre-freeze point. Therefore, having
>checkpointed the database at one freeze point and after garbage collection
>has run on all records, the most number of versions of a record would be
>two - the version that was committed at the time of the freeze and most
>recent version resulting from any subsequent changes.
>Where is the need for the most recent pre-freeze point version?

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.

Where is the need for the at-freeze point version?

Jim Starkey