At 12:14 AM 9/6/02 +0200, Boguslaw Brandys wrote:

>
>I agree that large size of database would be a problem ,but most of old
>committed records would only for redo log (for any other aspects would be
>invisible much more like roolback'ed ones , only wasted space) .Well, if it
>is a performance problem ,information about committed versions could be
>written into some internal table in case of internal garbage collection, but
>I insist that versioning still have journalling "inside" (we should only
>find the simplest way to get info about binding record transaction number
>with timestamp) .
>I hope You understand what I think in spite of my poor English ;-)
>

With disk < $100 per 100 GB, nobody care about the size of the
database. The problem is that as database fills up with useless
crud page locality goes to zero, the cache hit rate plumets, every
record reference is a page read, and performance tanks. Garbage
collection is cheap when all versions are on page becomes horribly
expensive when dozens or hundreds of pages must be referenced and
cleaned up.


Jim Starkey