Databases: Which one's right for me?

Aaron Watters aaron at reportlab.com
Mon Jan 12 02:12:46 CET 2004


"Tim Peters" <tim.one at comcast.net> wrote in message news:<mailman.284.1073847641.12720.python-list at python.org>...
> [Aaron Watters]
> > BTW, I would like to see somewhere an explanation of how
> > ZODB concurrency control and recovery work.  Please inform if
> > there is some information.  I'm not encouraged by the fact that
> > in what documentation I can find the definitions are not the
> > standard ones.
> 
> Of course you're much more likely to get a useful discussion of this on a
> ZODB list, like <mailto:zodb-dev at zope.org>.
> 
> "The standard" ones aren't all that standard.  ANSI SQL-92 defines multiple
> isolation levels, and they've been (I think) fairly critiqued as  incomplete
> and partly ambiguous; e.g.,
> 
>     A Critique of ANSI SQL Isolation Levels
>     Hal Berenson, et al.
>     http://citeseer.nj.nec.com/berenson95critique.html

Some SQL isolation levels are hacks to allow long running transactions,
etcetera.  If you keep to the strictest isolation level you get the
classical behaviour which has been studied and elaborated by many very
smart people over the last several decades and which is very well
understood.

Does ZODB support the strictest isolation levels?  If so how?  If not
what does it support exactly?
   -- Aaron Watters
===
We'll make our way across the galaxy
And head back home on the L.I.E.
   -- "Laser show", Fountains of Wayne



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