.. _db-versioning:

Database versioning
===================

Orthanc stores the index of the DICOM instances as an embedded `SQLite
database <https://www.sqlite.org/index.html>`_. The schema of this
database has evolved across the versions of Orthanc, making the
database incompatible between versions. This page clarifies which
versions of Orthanc are compatible with other versions.

Recent versions (post-0.3.1)
----------------------------

Recent versions of Orthanc (starting 0.3.1, inclusive) include
information about the version of the DB schema in the SQLite table
``GlobalProperties`` under the property with index 1. Versions with the
same version of the DB schema are compatible with each other.

When some version of Orthanc starts up, it checks whether it is
compatible with the database version. Orthanc will **fail to start if
it is not compatible with the database version**. Here is the
compatibility matrix:

===============================   =====   =====   =====   =====   =====
Version                           DB v2   DB v3   DB v4   DB v5   DB v6
===============================   =====   =====   =====   =====   =====
Mainline                                  u       u       u       x
Orthanc 0.9.5 - Orthanc 1.8.2             u       u       u       x
Orthanc 0.8.5 - Orthanc 0.9.4             u       u       x
Orthanc 0.7.3 - Orthanc 0.8.4             u       x
Orthanc 0.4.0 - Orthanc 0.7.2             x
Orthanc 0.3.1                     x
===============================   =====   =====   =====   =====   =====

*Note 1:* "u" means that an automatic upgrade of the DB schema is
available, without having to :ref:`migrate the database
<replication>`.

*Note 2:* Starting with Orthanc 0.9.5, the option ``--upgrade`` must be provided
on the command-line to allow Orthanc to upgrade the database schema.


Early versions (pre-0.3.0)
--------------------------

Early versions of Orthanc (up to version 0.3.0, inclusive) **do not
check the version** of the database schema. Because of this, these
early versions are incompatible with all the other versions. Pay
attention to the fact that no compatibility check is done in these
versions, which may result in a corrupted database.