[Zope] ZODB performance: reads to writes

[Evan Simpson]

----- Original Message -----
From: Jimmie Houchin <jhouchin@texoma.net>

> Will an app as described above still suffer from problems with high
writes?

Possibly, but only if there are hidden hotspots.  For example, in your
message-appending scenario, are these messages being added to the same
Folder?  If so, the Folder is getting written with each object added to it,
and will be a source of conflict.  If the objects that your users are
editing are cataloged, the Catalog is a hotspot.

There are two independent attacks on this problem underway:

1. Make Folders and Catalogs store meta-data about their contents in a data
structure consisting of small persistent objects, like B-Tree nodes.  This
reduces the scope of potential conflict (and the size of the update required
by a write) to the size of one of these nodes.

2. Implement the application-level conflict handling you read about, so that
Folders and Catalogs can decide that two writes don't conflict after all,
and merge them into a single update.

Cheers,

Evan @ digicool & 4-am