File store (was Re: Salutations)

Derek Atkins warlord@MIT.EDU
12 Dec 2000 13:09:22 -0500


David Merrill <dmerrill@lupercalia.net> writes:

> aisb, I consider the issue of closing the books and making all
> transactions prior to that immutable to be completely orthogonal to how
> the running total is determined. I am proposing a solution to the
> maintenance of running balances that scales well.

Can we assume that the Database itself can perform the necessary
arithmatic to update checkpoints when a transaction changes?  (Yes,
I'm showing my lack of database knowledge here -- please be gentle :)

Let me give an example...  You have 1000 transactions a day, so you do
daily checkpoints.  Let's assume you started your data on Jan 1, 1991.
Let's also assume that all transactions are still mutable.  On Dec 21,
2000 someone finds an error in transaction #1 (on Jan 1, 1991) and has
to change the value.  This implies that every checkpoint after that
date must be updated.  Can we assume that the database can perform
this operation quickly and efficiently on its own?

If so, great.  Let's move on to the next topic ;) If not, then we need
to worry about this issue.  

> I don't have an opinion on whether or not to close the books because
> I'm too ignorant about accounting practice. I have two semesters of
> college accounting, so I know basic concepts but that's it. I can say
> on my own account (tee hee!) that I scored top of my class in those
> classes, but that does not an accountant make.

Well, all closing the books really does is imply that:

	a) transactions prior to that date are considered immutable
	and cannot be modified

	b) you can place an immutable checkpoint at the date of
	closure.

I would think that this would solve the above update problem, since
you know you can only update data since the last closing date, which
limits the number of transactions (and intermediate checkpoints) that
could potentially change.

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
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