[ZODB-Dev] minimizing the need for database packing

[Jim Fulton]

On Dec 28, 2007, at 5:26 AM, Flavio Coelho wrote:

> Hi, is there any way to minimize the need for database packing? I  
> wouldn't mind loosing the ability of undoing transactions.


There's a significant performance benefit to keeping some non-current  
data to support multi-version concurrency control.

There Berkely Database Storage supported automatic incremental packing  
without garbage collection.  If someone were to revitalize that effort  
and if one was willing to do without cyclic garbage collection, then  
that storage would remove the need for the sort of disruptive pack we  
have with FileStorage now.

Note that I'm working on a new FileStorage packer that is 2-3 times  
faster and, I believe, much less disruptive than the current packing  
algorithm.  It also provides an option to skip garbage collection,  
making it twice again as fast.

It is available now as a separate monkey-patch in the zc.FileStorage  
package.

Jim

--
Jim Fulton
Zope Corporation