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

Shane Hathaway shane@zope.com
Mon, 24 Mar 2003 10:11:44 -0500

Chris Withers wrote:
> 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.

I can't think of an explanation.  I tried for 4 days. ;-)