[Digikam-users] Some questions about digikam4.db

Anders Stedtlund falolaf at gmail.com
Thu Nov 10 11:51:49 GMT 2011


My fault. Didn't mean to remove the thumbnails, just the db and have the
thumbnails in the filesystem instead.

The pro to have thumbnails in the same db as everything else must be that
it's possible to join over that table in a single run. Now I assume that
there's one query to find images and another query to find the thumbnails.

Den 10 nov 2011 11:55 skrev "Jean-François Rabasse" <
jean-francois.rabasse at wanadoo.fr>:

> On Thu, 10 Nov 2011, Anders Stedtlund wrote:
>  Hi Jean-François,
>> digiKam used to have thumbnail images in the file system. Do you
>> suggest that the thumbnails db should be removed in the future? (If I
>> read between the lines...)
> Hi Anders,
> Oh no, I didn't meant "removed"; having thumbnaisl under hand is an
> important feature for such an application.
> My opinion is that that kind of data, thumbnails or fingerprints,
> should probably not be part of the master DB file.
> Because it's not part of the DB schema, it's only auxiliary data,
> setup in advance for faster access upon need, and can be rebuilt at
> any time, so don't need to be backuped even in case of disk disaster.
> But saving that data "outside" the master DB, be it into another DB
> file or in the file system, or whatever, is of little importance, the
> application knows how to get it and it's only a development choice.
> The inconvenient of "packing" all in one DB file is size (as was the
> start point of this thread). When one looks at Digikam versions using
> two files, digikam4.db and thumbnails-digikam.db, one sees the second
> file is about 10 times bigger !
> Jean-François
> PS: another argument for the "splitted" philosophy is when an images
> application runs on different machines. It's probably not a Digikam
> issue, but it's a common configuration in web based images bank
> applications; the main application (CGI program) is on one machine
> running a HTTP server, the database is on another machine running a
> SQL server, Oracle, PorsgreSQL, MySQL, etc., protected on a local
> network.
> The design rule says "data should be where it's needed", so the
> application will access master DB data via SQL requests, but will
> load and send/display thumbnails images from it's local disk system.
> If you put thumbnails in the main DB, you jam your local network
> bandwidth.
> So, splitting -> more flexibility and in some cases higher performances.
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