How to create a protected table in teradata?

Question

i am using

create table xxx fallback,
                 before journal,
                 after journal,
                 checksum=default
(
    field1 integer,
    field2 integer 
)
primary index field1 ; 

---

But i do not know if this is completely okay . i have some questions :

1) can i use before journal and after journal at the same time ?

2) both before journal and after journal are used for backing up the table ? what is the difference ?

3) does fallback fully cover for both journals ?

4) is it important to have checksum ?

Answer 1

1) Of course you can do both before and after journal on a table. If you couldn't, the parser would complain about it :-)

2) before journal is used for rollback (undo log) and after journal for rollforward (redo log). So it might be a part of a backup solution.

3) fallback stores every row twice, including journal rows.

4) checksum is a disk I/O integrity check, i've hardly seen it used.

You might check the DDL and the Database Design manual for details.