[MarkLogic Dev General] What does the ML Journal contain ?

[Danny Sinang]

Hi Ron,

Thanks for the info.

So in effect, the journal entries somehow store the actions to be taken,
not the new data to be applied ?

I'm asking this to somehow assure myself that journal entry creation would
be fast, even for large transactions. The faster the journal creation, the
less chances of it failing due to an outage.

Regards,
Danny

On Fri, Apr 20, 2012 at 8:58 AM, Ron Hitchens <ron at ronsoft.com> wrote:

>
>   No user serviceable parts inside.
>
>   The journal contains information that describes
> sets of updates done by transactions.  In case of a
> crash, the journal can be replayed to re-apply any
> updates that may not yet have been written to the
> on-disk forests.
>
>   A transaction does not complete until the journal
> entry is written to disk, but the corresponding updates
> to the forest(s) are written later.  The database view
> your queries see are the sum of the on-disk in in-memory
> stands that comprise forests which make up a database.
>
>   Journal entries are in a compact binary format that
> is only used internally by the server to assure data
> consistency.
>
> On Apr 20, 2012, at 1:43 PM, Danny Sinang wrote:
>
> > Hi,
> >
> > I'm told that for document inserts and updates, an ML journal entry gets
> written.
> >
> > Does anyone know what gets written to the journal ? Is it just the
> xquery getting executed ? Or is it the new data to be appended to the
> database ?
> >
> > Regards,
> > Danny
> >
> > _______________________________________________
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> > General at developer.marklogic.com
> > http://developer.marklogic.com/mailman/listinfo/general
>
> ---
> Ron Hitchens {mailto:ron at ronsoft.com}   Ronsoft Technologies
>     +44 7879 358 212 (voice)          http://www.ronsoft.com
>     +1 707 924 3878 (fax)              Bit Twiddling At Its Finest
> "No amount of belief establishes any fact." -Unknown
>
>
>
>
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