Snippets in Tracker’s full text search results

After quite some time without touching Tracker code, last week I finally could get back to a branch that’s been sitting there for some time now. On fts4, sqlite requirements have been updated to >=3.7.9 so we can stop compiling our custom FTS module and start using what comes with libsqlite.

What does this mean? Internally there’s less code on our plate (and non-stale), and external content support in FTS tables brings us no performance nor file size decreases. plus we get all recent hot improvements in sqlite releases for free.

A bit more on the user point of view, a feature that became possible with this swich is the support for fts:snippet(), which you can use in SparQL queries to get snippets of the matched text:


$ tracker-sparql -q "select nie:url(?file) fts:snippet(?file) fts:rank(?file) where { ?file a nfo:Document ; fts:match 'reference' } order by desc (fts:rank(?file)) limit 3"
Results:
file:///home/carlos/Documents/Papers/pdf_reference_1-7.pdf, ...Reference Streams G8.1872911 Cross-Reference..., 46.0
file:///home/carlos/Downloads/addison.pdf, ...GLU are described in the OpenGL
Reference Manual. The more useful GLU..., 40.0
file:///home/carlos/Downloads/ThesisHo.pdf, ...A8 ]+ ) is also included for
reference. In the third experiment, we apply..., 40.0

So its easier to the eye, tracker-needle search tool now also shows snippets where available, providing a nice context for the matched content

tracker-needle

Remember that FTS searches apply to any property that’s specified by the ontology as tracker:fulltextIndexed, you can run this to find out:

tracker-sparql -q "select ?prop rdfs:label(?prop) tracker:weight(?prop) where { ?prop tracker:fulltextIndexed true }"

There’s also the possibility you had no idea what I’m talking about :), If desktop semantic search still tickles your curiosity I’ll point you to the fine gathered documentation about Tracker.

This work was kindly sponsored by Lanedo.

2 Responses to “Snippets in Tracker’s full text search results”

  1. Very nice, great work Carlos!

  2. [...] Carlos added FTS4 and snippet support to Tracker. We merged that to master after doing some tests and have reduced the database [...]