exceeded maximum allowable context number

  Explanation:  The number of contexts used in a  request  exceeds
  the  limit,  where a context is defined as a cursor value source
  or a query/subquery.  (Note that  the  term  "context"  is  used
  differently  here  than elsewhere in Oracle Rdb.) A cursor value
  source consists of a table, aggregate, EXISTS predicate,  UNIQUE
  predicate,  quantified  predicate  or UNION clause in a request.
  In terms of BLR, a cursor value is any of the  following  BLR$K_
  objects:   AGGREGATE,  ALL,  ANY,  ANY2,  AVERAGE,  COUNT, FROM,
  MAXIMUM, MERGE, MINIMUM, RELATION, RELATION_ID,  TOTAL,  UNIQUE,
  VIA.   Cursor values are obtained from a user-generated request;
  or from the BLR associated with a view, constraint, trigger,  or
  other  metadata object.  Cursor queries/sub-queries are produced
  for each record selection expression (RSE) and FETCH statement.

  User Action:  If you called Oracle Rdb, check the  query  string
  and  simplify  if  possible.   Otherwise,  Contact  your  Oracle
  support representative for assistance.