[Digikam-users] Any thoughts on RAM needs?

Jean-Francois jean-francois.rabasse at wanadoo.fr
Tue Sep 13 16:50:15 BST 2011

On Tue, 13 Sep 2011, Jean-Daniel Dodin wrote:

> Jean-Francois wrote:
>> By the way, a cleanup, or integrity check, should require to run the
> (...)
> very interesting. Is it stable enough to be used in a cron script
> (monthly, for example, with backup rotation)

Is it stable ? Well, 'vacuum' is a SQL command, not strictly in the 
standards but implemented by all RDBMS software providers.
There's no more risk to use this than to use any other SQL command
that will modify your database, INSERT INTO, UPDATE, etc.

It will be stable if you use a stable production version of your DB
software, PostgreSQL, MySQL, SQLite, whatever.
It may be buggy if you use a buggy CVS snapshot of the alpha.
version of the next release of the software. As usual :-)

All these commands can be issued from the related command line client.
With SQLite :
   sqlite3 -line mybase.db 'vacuum;'
With PostgreSQL :
   psql -d mybase -h myserver -c 'vacuum;'

And thus, it is very easy to cron.

Doing cleanup along backup rotation is context specific, a matter of
data volume, and processing time.
If you have several large sized database, say 50 Tbytes to 200 Tbytes,
installed on a reasonably safe system, e.g. RAID5 or 6 disks server,
you'll probably consider doing a weekly backup because it will cost
hours and hours of network traffic.

But if your databases are subject to intensive daily use, a daily
'vaccum' will take several minutes and can be cron'ed at 3 or 4a.m.,
when 99% of users are sleeping.
In that case it will be better to split backup and cleanup operations.

For small volume databases, with a low operations daily rate, the two
can be done at the same time.


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