[ZODB-Dev] how big can a ZODB get?

[Victor Ng]

Thanks Jeremy!

I have two questions though:
 - What's a hop?
 - What's a second-class persistent object?

vic

> An application uses one or more database connections
> (ZODB.Connection).  Each connection has its own in-memory cache of
> objects.  The cache size is measured in objects, even though the
> amount of memory used by individual objects varies greatly.  The cache
> also keeps "ghost" objects, which uses on the order of 100 bytes of
> memory; it keeps a ghost for every object that is directly (one-hop)
> reachable from cached objects.
...
> The way you implement objects has an obvious impact on memory usage.
> ZODB loads a first-class persistent object as an atomic unit; it also
> loads all reachable second-class persistent objects as the same time.