ctxsys.context

Database Version 12.1.0.2.0

I created a MULTI_COLUMN_DATASTORE ctxsys.context on a very large table, ie:

ctx_ddl.create_preference('multi_store','MULTI_COLUMN_DATASTORE');

ctx_ddl.set_attribute('multi_store',

                      'columns',

                      'c1,c2,c3,c4'

                     );

CREATE INDEX "TEST"."CTX_SRCH_IDX" ON "TEST"."BIGTABLE" ("FIRSTNAME")

   INDEXTYPE IS "CTXSYS"."CONTEXT"  PARAMETERS ('DATASTORE multi_store section group ctxsys.auto_section_group sync (on commit)') ;

When I search, the results are blazing fast, ie:

  select  *

  from

    TEST.BIGTABLE t

  where contains (t.FIRSTNAME, 'kenneth and band') > 0

This query would search 50 million records in 1 second, and return 11 results as expected.  But whenever i add another limiting factor on another column (that has normal btree index, the 'filtered' result takes about 20 seconds, ie: