OEM views meeting 2/12/97
Attendees: Serge, Jason, Roy, Vasilis, Yue.

We first discussed how to do materialized view maintenance. 
The major problem identified, that makes maintenance more
difficult than in relational systems, is object sharing. 
Changing an object or creating or deleting an edge can "affect" 
many objects  that point to this object (and thus recursively
a large portion of the database).

A couple of ideas came up to handle this problem:

-Maintaining explicit back pointers in all objects. Not a very good
idea, because 
i) of space considerations 
ii) it imposes an unnecessary performance penalty on all users and all
objects (whether a view has been defined or not)

-using the lindex to get the set of objects that point to
a given object. 

- another idea was to maintain "summary" tables for entire paths
ie a table for A.B.C would keep the pairs of nodes that are connected
thru a A.B.C path.
These tables need to be kept up to date , ie maintained after every update
to the DB.

We also discussed using triggers to do the maintenance.