[ZODB-Dev] High Write Applications

[Phillip J. Eby]

At 12:10 PM 8/4/03 +0100, Chris Withers wrote:
>Phillip J. Eby wrote:
>
>>>I haven't ;-) Where can I read more?
>>Google for "Prevayler".
>
>Quick scan suggest that Prevayler is roughly ZODB for Java. Is that a fair 
>statement?

No.  ZODB does object persistence, Prevayler does object prevalence.  It 
needs a lot more memory than most ZODB implementations, but handles high 
write volumes.  It doesn't demand that you subclass a particular base 
class, but it does demand that you create "command" objects that can 
represent any transaction you want to perform.

Note also that there is a Prevayler-like system for Python: PyPersyst.

The nice thing about a prevalence architecture is that it's dramatically 
simpler than a persistence architecture, provided you 1) have the memory 
and 2) don't mind architecting around command classes, and 3) don't mind 
taking forever for an application to restart.  I have some thoughts about 
how to make #2 relatively transparent, but #1 and #3 are generally more of 
an issue.