ORA-01647
Tried to move a table to another tablespace, but it failed with ORA-01647.
SQL> alter table employees move tablespace example;
alter table employees move tablespace example
*
ERROR at line 1:
ORA-01647: tablespace 'EXAMPLE' is read-only, cannot allocate space in it
ORA-01647 means that the target tablespace is in READ ONLY, there's no way to allocate space in the tablespace for your segment.
Let's see current status of the tablespace.
SQL> select status from dba_tablespaces where tablespace_name = 'EXAMPLE';
STATUS
---------
READ ONLY
OK, it's really READ ONLY.
Solution
To solve ORA-01647, we should revert the tablespace back to READ WRITE:
SQL> alter tablespace example read write;
Tablespace altered.
SQL> select status from dba_tablespaces where tablespace_name = 'EXAMPLE';
STATUS
---------
ONLINE
Now we can move the table again.
SQL> alter table employees move tablespace example;
Table altered.
We solved it.