Views Automatically invalidated

Question

Hi
I have created some force views in my database. Every morning when i check the invalid objects these views are automactically invalidated. When i compile them they get valid and again the next day they become invalid.
The view is a join of 2-3 tables and every night one of the tables is truncated, the indexes are dropped ,data inserted and indexes are recreated.
Any other ddl is not fired on any of the tables in the view.
The version of oracle :
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE 10.2.0.4.0 Production
TNS for Linux: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production
Regards
Ankit

Answer 1

Problem lies with your index recreation. The indexed columns are referenced in your view. Below example will illustrate my point.
SQL>
SQL> select * from rag;
       NID        SID
         1        100
         2        200
         3        200
         5        200
         6        100
         8        200
         9        100
7 rows selected.
SQL> create unique index RAG_UK ON RAG(NID);
Index created.
SQL> create view RAG_VIEW AS select NID,NID+10 Val from RAG;
View created.
SQL> select object_name,object_type,status from
  2  user_objects where object_name='RAG_VIEW';
OBJECT_NAME                                                                                                                      OBJECT_TYPE         STATUS
RAG_VIEW                                                                                                                         VIEW                VALID
SQL> drop index RAG_UK;
Index dropped.
SQL> create unique index RAG_UK ON RAG(NID);
Index created.
SQL>  select object_name,object_type,status from
  2   user_objects where object_name='RAG_VIEW';
OBJECT_NAME                                                                                                                      OBJECT_TYPE         STATUS
RAG_VIEW                                                                                                                         VIEW                INVALID