[Zope-dev] Cache growing during single REQUEST

[Chris Withers]

Tim Peters wrote:
> Probably none for many apps.  You'll be working with possibly non-current
> data, so think of ways your apps could possibly be damaged by that.  For
> example, you're Bill Gates, using ZODB to track all your assets.  A summary
> report takes hours to generate, and by the time you get it, perhaps a few of
> your billion-dollar overseas accounts were wiped out in the wee hours by an
> adverse court judgment, but the total you get added in the account values as
> of the time the report-generating transaction began.  Oops.  To the extent
> that MVCC hides that you're working with non-current data, to that extent
> also does an app relying on current data become vulnerable.  When Bill is
> contemplating fleeing the country during turbulent times, he presumably
> needs to know how much cash he has right now, not what he had last night.
> Most apps aren't like that, but a one-size-fits-all policy for long-running
> transactions (like Bill's) doesn't exist.

Ah, okay. That all makes sense...

Of course, Bill may appreciate having a report that says "based on data no newer 
than X" where X is the time the transaction to generate the report started, 
rather than no report at all due to lots of read conflicts ;-)

Chris