[Digikam-users] lots of photos and startup time

Andi Clemens andi.clemens at gmx.net
Thu Jul 9 09:45:47 BST 2009

Until now I have not seen any query that might not work.
I guess the other way around would be more difficult (MySQL->sqlite).

Startup times (especially with a MySQL server) will be faster for sure, since 
the server already loads the database handles into memory).

Access will be faster, too, but unfortunately memory consumption will be 
increased as well.
Right now digiKam uses 160 MB RAM on startup on my system, during a digiKam 
session I mostly end up with 270MB RAM.
With MySQL the two databases will take much more memory, and especially with 
the thumbsDB this can be a problem again.
MySQL caches a lot into memory, that's why it is (also) faster.

I will try to create the two databases in mysql today, import the data and see 
how much memory the server will use initially.
Then I will query via a script some basic operations that I would do inside of 

If memory usage goes high, we could have another problem again :-)
The "problem" with our two databases is that we use a lot of binary data (in 
forms of blobs) in there.
When they are cached in memory, I don't know what will happen.


On Thursday 09 July 2009 10:30:35 Marcel Wiesweg wrote:
> > Marcel, Andi,
> >
> > All this thread tell me that we need to found urgently a solution to
> > this problem.
> >
> > If sqlite cannot drive large database, another DB backend need to be
> > used. For me MySql sound like the right alternative, if performance
> > are there of course (how to make a quick test about ?)
> >
> > About DB schema and all DB queries, it's really complicated to migrate
> > from SQLite to MySql. SQL syntax is really different between both DB
> > backend ?
> I am not sure how much difference is there.
> I would expect that 90% of our statements will work for both, as most are
> simple.
> We would need to test the schema definition, think about using the correct
> character set everywhere - SQLite is fully UTF-8 so this always just
> worked, MySQL may need some explicit options for UTF-8, and test with
> complex queries from the advanced search.
> > Gilles
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