[Zope] DBTab product questions (more...)

[Chris Withers]

Shane Hathaway wrote:
> On Wed, 19 Mar 2003, Thierry FLORAC wrote:
> 
>>And another one : does the fact of splitting a Zope site between several ZODBs 
>>can have any impact (improvement or not) on the whole performances ??
> 
> There is no measurable difference in performance unless you mount a large
> number of databases.  The MountPoint._setDB() and MountPoint.close() 
> methods are the issue here: they have to open/close all mounted 
> connections, even if they won't be used in the course of a transaction.  

Hmmm... well, just a data point, but since I moved one of our big setups (Two 
ClientStorages mounted into another ClientStorage) from ExtMount to DBTab, I've 
noticed that the first object loaded from a mounted storage takes 
significantly(and I do mean significant ;-) longer than it used to and longer 
than any subsequent loads of objects from that storage. I wonder what's taking 
the time? The mounted storages all have fairly large (100-400Mb) ZEO client 
caches, but they were that way with ExtMount too.

The only other difference I can think of is that one of the mounted storages is 
basically a folder with about 11,000 items in it. This used to be a BTreeFolder 
but I've moved it to a BTreeFolder2 (mainly in order to stop the ZMI left pane 
killing hte machine by trying to load all 11,000 objects into memory :-S )

Any ideas?

cheers,

Chris