
The Query Planner now expands the plan for quer y 1 in a second pass by generating three
subqueries:
(queryla, userl, userl, "find all documents on compilers")
(querylb, userl,
userd,
"find all documents on compilers")
(querylc, userl, userl', "find all documents on compilers")
Assume that userl, userS and userl are supported by three different workstations.
The Network Server transmits querylb and querylc to the respective nodes, nodeB and
nodeC, where they are placed on their respective Query Blackboards. The Query Plan-
ners at all three nodes process the subqueries locally and place the resulting documents
on the respective Response Blackboards ...