Dear everybody. This is my question that needs to be answered. option or create a simple materialized view. select IR.rowid MV_INST_LOBR_ROWID, J.rowid Job_ROWID, J.* FROM JOB J LEFT JOIN MV_INST_LOB_R IR ON (IR.I1503_CUST_AC_NO_PT1 = J.I3200_CUST_AC_NO_PT1 AND IR.I1503_CUST_AC_NO_PT2 = J.I3200_CUST_AC_NO_PT2 AND IR.I1503_INST_SEQ_NO = J.I3200_INST_SEQ_NO) WHERE IR.I1503_CUST_AC_NO_PT1 IS NOT NULL AND IR.I1503_CUST_AC_NO_PT2 IS NOT NULL UNION SELECT null, J.rowid Job_ROWID, J.* FROM JOB J WHERE J.I3200_CUST_AC_NO_PT1 IS NULL AND J.I3200_CUST_AC_NO_PT1 IS NULL; Basically, the intention is to get all the records joining MV_INST_LOB_R and JOB table where MV_INST_LOB_R do not have record for the joining condition J.I3200_CUST_AC_NO_PT1 / J.I3200_CUST_AC_NO_PT2 I am trying to use this in a materialized view and got below error: SQL Error: ORA-12015: cannot create a fast refresh materialized view from a complex query. I have searched for help on the internet and still have not found a solution. 12015. 00000 - "cannot create a fast refresh materialized view from a complex query" *Cause: Neither ROWIDs and nor primary key constraints are supported for complex queries. *Action: Reissue the command with the REFRESH FORCE or REFRESH COMPLETE Can you help me in converting to simple query, so that I can use simple materialized view. Thank's a lot!