The following options are related to Ansel’s library database and XMP sidecar files.


check for database maintenance
Indicates when darktable should check for database fragmentation and perform maintenance. Options are “never”, “on startup”, “on close” and “on both”. Each of these is also available with an additional “(don’t ask)” option to perform the checks automatically without prompting (default “on close”).
database fragmentation ratio threshold
Fragmentation ratio (in per cent) above which database maintenance should be performed (subject to the selection made in the option above) (default 25).
create database snapshot
Specifies how often Ansel should create database snapshots. Options are “never”, “once a month”, “once a week”, “once a day” and “on close” (default “once a week”)
how many snapshots to keep
Number of snapshots to keep after creating a new snapshot, not counting database backups taken when moving between Ansel versions. Enter “-1” to store an unlimited number of snapshots. (default 10)


write sidecar file for each image
XMP files provide a redundant method of saving the changes that you have made to an image, in addition to the changes saved to Ansel’s database. This option allows you to choose when to write these files. Choose from:
  • never: Don’t write XMP files. This can be useful if you are running multiple version of Ansel for development/testing purposes but is not normally recommended
  • on import: An XMP file will be written as soon as you add an image to Ansel’s library and will be subsequently updated each time you edit it
  • after edit: An XMP file will be written the first time you perform an edit on an image and will be updated on each subsequent edit. Importing will not generate an XMP file by default.

It’s strongly recommended that you choose either “on import” or “after edit”. XMP files provide a useful fail-safe so that you don’t lose data if your database becomes corrupted. Backing up your raw file plus the accompanying XMP file will allow you to fully restore your work at a later date by re-importing your edit history back into Ansel (default “on import”).

store xmp tags in compressed format
Entries in XMP tags can get rather large and may exceed the available space to store the history stack in some output files on export. This option allows binary XMP tags to be compressed in order to save space. Available options are “never”, “always”, and “only large entries” (default).
look for updated xmp files on startup
Scan all previously-known XMP files on startup and check if any have been updated in the meantime by some other software. If updated XMP files are found, a menu is opened for the user to choose if the XMP content should be used to update the database or the other way around (replacing Ansel’s database entries by the XMP file contents). Activating this option also causes Ansel to check for text sidecar files that have been added after import time (default off). This makes the application take more time to load, especially if your files are hosted remotely (on a server or on a NAS).