ORA-23515: Materialized Views and/or Their Indices Exist in the Tablespace While dropping any Tablespace, you might get the errror ORA-23515: Materialized Views and/or Their Indices Exist in the Tablespace This is due to the fact that the tablespace contains the indexes or Materialized views You may use the following queries to find out which materialized views and/or which indeces of materialized view container tables are on the tablespace you intend to drop. Once these objects are found you can move the tables, rebuild indeces in other tablespace. select s.sowner MV_OWNER, s.tname MV_NAME, p.name TABLESPACE from sys.obj$ o, sys.tab$ t, sys.user$ u, sys.snap$ s , sys.ts$ p where t.ts#=p.ts# and p.name='<tablespace_name>' and t.obj#=o.obj# and o.owner#=u.user# and u.name=s.sowner and o.name=s.tname order by 1,2; select o.owner, o.object_name index_name, o.object_type, sq.mv_owner,sq.mv_name,sq.tablespace from dba_objects o, ...