There are more than one database managed by digiKam :

- Core database which host all albums, items, searches data.
- Thumbnails database to host image thumbs with wavelets compression images.
- Similarity database to host image finger-prints with computed Haar algorithms.
- Face database to host face areas on images and face histograms used by faces recognition.
  For technical reasons, code is located in libs/facesengine/facedb.

Directory         | Description
------------------|-------------------------------------------------------------------------------------
collection/       | Collections management interface.
coredb/           | Core database implementation based on Database Engine.
dbjobs/           | Database jobs manager.
engine/           | Low Level database engine common to all database interface.
haar/             | Haar fingerprint algorithms used by Fuzzy Search tool.
history/          | Item history algorithms.
imgqsort/         | Image Quality algorithms.
item/             | Item management interfaces.
server/           | Internal database server.
similaritydb/     | Similarity database implementation based on Database Engine
tags/             | Tags management and Face tags interface.
thumbsdb/         | Thumbnails database implementation based on Database Engine.
utils/            | High level implementation based on Core database interface plus widgets and dialogs.
