.. _modify-schema:

Modify Feature Vector Database Structure
===========================================

Sometimes it may be necessary to apply a new structural schema to your Tarantool-based feature vector database, for example, when updating to the latest version of the product, or when you want to enhance the default database structure with additional parameters, advanced face metadata, and so on.

.. rubric:: In this section:

.. contents::
   :local:

About Database Structure
------------------------------

In FindFace Multi, the database structure is set via the ``/opt/findface-multi/configs/findface-tarantool-server/tnt-schema.lua`` file.

The structure is created as a set of spaces and fields. Each field is described with the following parameters:

* ``id``: field id;
* ``name``: field name, must be the same as the name of a relevant object parameter;
* ``field_type``: data type (``unsigned|string|set[string]|set[unsigned]``);
* ``default``: field default value. If a default value exceeds ``1e14 – 1``, use a string data type to specify it, for example, ``"123123.."`` instead of ``123123..``.

You can find the default ``tnt_schema.lua`` file :download:`here <_scripts/tnt_schema.lua.txt>`.


Structure Modification
--------------------------------


To modify the database structure, do the following:

#. Create a backup of the Tarantool-based feature vector database in any directory of your choice, for example, ``/etc/ffmulti_dump``. 
 
   .. code::

      sudo docker exec -it findface-multi-findface-sf-api-1 bash -c "mkdir ffmulti_dump; cd ffmulti_dump && /storage-api-dump -config /etc/findface-sf-api.ini"
      sudo docker cp findface-multi-findface-sf-api-1:/ffmulti_dump /etc
 
#. Modify the database structure by applying the new schema to the ``tnt_schema.lua`` file.
 
   .. code::

      sudo docker run --rm --network host --volume '/opt/findface-multi/configs/findface-multi-legacy/findface-multi-legacy.py:/etc/findface-security/config.py:ro' docker.int.ntl/ntech/multi/multi/legacy:ffmulti-2.0.0 make-tnt-schema | sudo tee /opt/findface-multi/configs/findface-tarantool-server/tnt-schema.lua

#. Navigate to the directory with Tarantool configuration file(s) ``/opt/findface-multi/configs/findface-tarantool-server/``. For each shard ``shard-00*.lua``, check whether it contains the ``dofile`` command. Make sure the ``replication`` and ``spaces`` are defined within the ``FindFace.start`` parameter, as in the example below. 

   .. code::

      sudo vi /opt/findface-multi/configs/findface-tarantool-server/shard-00*.lua
      
      dofile("/tnt_schema.lua")


      -- host:port to bind, HTTP API
      FindFace = require("FindFace")
      FindFace.start("127.0.0.1", 8101, {
          license_ntls_server="127.0.0.1:3133",
          replication = replication_master,
          spaces = spaces
      })
 
#. Purge data from all the directories relevant to active shards.
 
   .. code::

      sudo rm /opt/findface-multi/data/findface-tarantool-server/shard-*/{index,snapshots,xlogs}/*

#. Restart the ``findface-tarantool-server`` shards.

   .. code::

      docker restart findface-multi-findface-tarantool-server-shard-001-1 findface-multi-findface-tarantool-server-shard-002-1 findface-multi-findface-tarantool-server-shard-003-1 findface-multi-findface-tarantool-server-shard-004-1 findface-multi-findface-tarantool-server-shard-005-1 findface-multi-findface-tarantool-server-shard-006-1 findface-multi-findface-tarantool-server-shard-007-1 findface-multi-findface-tarantool-server-shard-008-1

#. Restore the Tarantool database from the backup.
 
   .. code::

      sudo docker exec -it findface-multi-findface-sf-api-1 bash -c 'cd ffmulti_dump && for x in *.json; do /storage-api-restore -config /etc/findface-sf-api.ini < "$x"; done;'

   .. important::
      If some fields were removed from the new database structure, you have to first manually delete the corresponding data from the backup copy.  


.. seealso::
   :ref:`custom-metadata`