What to do to change materialized view column size when under line table column size changed?

Question

What to do to change materialized view column size when under line table column size changed? This is oracle 11gR2 db on Linux. I tried recompile the MV, it didn't work. Please do not auto migrate this question to another database site, I want to stay here in stackoverflow. Thanks!

Answer 1

If you alter the table you must also alter the materialized view.

--Create simple table and materialized view
create table test1(a varchar2(1 char));
create materialized view mv_test1 as select a from test1;

--Increase column width of column in the table
alter table test1 modify (a varchar2(2 char));

--Insert new value that uses full size
insert into test1 values('12');

--Try to compile and refresh the materialized view
alter materialized view mv_test1 compile;
begin
    dbms_mview.refresh(user||'.MV_TEST1');
end;
/

ORA-12008: error in materialized view refresh path
ORA-12899: value too large for column "JHELLER"."MV_TEST1"."A" (actual: 2, maximum: 1)
ORA-06512: at "SYS.DBMS_SNAPSHOT", line 2563
ORA-06512: at "SYS.DBMS_SNAPSHOT", line 2776
ORA-06512: at "SYS.DBMS_SNAPSHOT", line 2745
ORA-06512: at line 3

--Increase column width of column in the materialized view and refresh
alter materialized view mv_test1 modify (a varchar2(2 char));
begin
    dbms_mview.refresh(user||'.MV_TEST1');
end;
/
select * from mv_test1;
A
--
12