Opal manages databases for two distinct purposes: for holding the participants identifiers and for holding the variable catalog and participant data. Since Opal 3.0, it is not required to set up neither an identifiers database, nor a data database:
- If no identifiers database is defined, the :ref:`ids` service when performing import/export will be disabled.
- If no data database is defined, no data can be imported in any project, only :ref:`resources` can be defined and used for analysis.
.. toctree:: :maxdepth: 1 :caption: System administration/general-settings administration/identity-providers administration/r administration/datashield administration/taxonomies administration/databases administration/plugins administration/apps administration/jvm