Re: [Shotwell] Extracting image tags from shotwell

[René Seindal <rene seindal dk>]

On 2016-11-21 09:43, Jens Georg wrote:
> Hi,
>
> I'm not that familiar with the DB structure tbh, last time I checked the
> tag handling seemed rather counter-intuitive. I'll check and get back to
> you.

From what I've gleaned, the database is not normalised.

The tag-photo relation is a many-to-many relation, but the photos and 
videos tagged are listed directly in a text field in the TagTable.  This 
field can grow to enormous dimensions.

I have a database with 280,000 work related photos with probably an 
average of 3-4 tags each, organised hierarchically, and the TagTable 
text field can grow to be about 600kb for some of the top level tags.

I believe this is also one of the reasons why some tag related 
operations are extremely show on that installation, as a simple removed 
tag from one photo might require several reads and writes of 600kb blocks.

The 'correct' way would be to have a TagPhotoTable with just the two ids 
and double indices so joins on either id will be efficient.

I don't if  there should be TagPhotoTable and TagVideoTable, each with 
just two ids,  or a shared TagPhotoTable table with the two ids and a 
type field too indicate whether the tag is for a photo or a video.

The DB queries will be slightly more complicated, but it should be way 
faster on databases with many tags and photos.

René


> > Hi,
> >
> > I have a large set of tags in shotwell and I am trying to export the
> > tags for each image from the shotwell sqlite database.   Are the tags
> > for each image stored in some field in the PhotoTable table?
> >
> > I also see the TagTable, whhere for each tag lists all the thumbnail
> > filenames.  But I don't know how to find the original image filename
> > from thumbnails.  In the PhotoTable, there are  thumnail_md5 and
> > exif_md5, but I don't know if these md5's are relevant or index to
> > another table or not.
> >
> > Any help is appreciated.   We spet a lot of time tagging our images in
> > shotwell and now stuck extracting them.
> >
> > Thanks
> > -P
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--
René Seindal - rene seindal dk