Journal file -- recommended to use always.

[Ruslan Zasukhin]

On 4/10/12 8:34 AM, "Fabian Kneubuehl" <support at ysd.ch> wrote:

> Ruslan,
> 
> I don't criticize the idea of journaling, but I think that this is not
> useful if I flush each DB change, right?

Not exactly right.

1)

Because now with journal, you can consider db.Flush()
As kind of transaction commit.

And you can write your code as

    1) make changes in T1
    2) make changes in T2
    3) make changes in some T12 which link them
    
    4) db.Flush()  == COMMIT.

Without journal, if you crash happens right after db engine did WRITE into
t1, for example, on next open you will get DB with inconsistent LOGICAL
data,

With Journal, such changes will be roll-back automatically to previous
consistent state.


2) 

EVEN if you do changes in T1, you should understand that internally in DB
this can be FEW writes to disk into different places of db. Right?

And IF system dies in THIS moment, you get corrupted db without journal.

Journal protect you from such corruptions.


** VERY RECOMMENDED to use Journal always,

*** ONLY EXCEPTION CAN BE

    * admin of db make BACKUP
    * then he need load into db million records
        then he disable journal on this operation.

In case of troubles, he has backup and can return manually to good state.


--- PAYMENT for journal is not so big.  ----



-- 
Best regards,

Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc

Valentina - Joining Worlds of Information
http://www.paradigmasoft.com

[I feel the need: the need for speed]