.. highlight:: rst

.. _scdb:

####
scdb
####

**Populate a SQL database from XML files or messages.**


Description
===========

A major component of the SeisComP system is the database. Almost all
applications have only read access to the database, but all the processing
results and objects have to be written into the database. This was the task of
scdb. In very first versions of SeisComP scdb was the only component that had
write access to the database. Its task is to connect to :ref:`scmaster` and populate
the database with all received notifier messages. Although it worked it
introduced race conditions caused by the latency of the database backend since
all other clients received the message at the same time. Accessing the database
immediately at this point in time did not guarantee that the object was
written already.

In consequence, the scmaster itself gained write access to the database and
forwards messages to all clients after they are written to database.

:ref:`scdb` by definition does not check existing objects in the database. It only
generates INSERT/UPDATE/DELETE statements based on the data used and sends
these statements to the database. E.g. if :ref:`scdb` receives a message to
insert a new object into the database and this object exists already, the
database will raise an error because :ref:`scdb` hasn't checked it.


Online mode
-----------

Now scdb can be used to maintain a backup or archive the database that is not
part of the real time processing. When running scdb as database write daemon it
can inform a client about the database connection to use. A client sends a
DatabaseRequest message and scdb sends back a DatabaseResponse message containing
the database connection parameters.

For that it connects to a messaging server and writes all received messages to a
configured database, e.g. a backup database.

.. note::

   The database connection received from the messaging server during the
   handshake is reported to clients requesting a database address. To overwrite
   the read-only database, just override the application's database address
   (with the '-d' option)

Offline mode
------------

Another important task of :ref:`scdb` is to populate the database with any SeisComP
data model content. In combination with :ref:`scxmldump` it can be used to copy events
from one database to another.

For that it does not connect to a messaging server but reads data from XML
files and writes it to the database. Offline mode will be used if the
'--input/-i' option is provided. Multiple input files can be specified by
providing this option multiple times with separate filenames.

.. warning::

   When reading XML files the output database address is not passed
   with -o but -d. The application's database address is used.

Examples
--------

#. Connect to a messaging server and write all messages to the output database
   `seiscomp` running on the host `db-server`:

   .. code-block:: sh

      scdb -H [server] -o mysql://sysop:sysop@db-server/seiscomp

#. As above, but with the read-only database connection using the user `sysop`
   and the output database connection using the user `writer`:

   .. code-block:: sh

      scdb -H [server] -d mysql://sysop:sysop@db-server/seiscomp \
                       -o mysql://writer:12345@db-server/seiscomp

#. Import data from the file :file:`data.xml` and write it to the database
   `seiscomp` on the host `db-server`:

   .. code-block:: sh

      scdb -i data.xml -d mysql://sysop:sysop@db-server/seiscomp

#. Import data from three files at once:

   .. code-block:: sh

      scdb -i data1.xml -i data2.xml -i data3.xml \
           -d mysql://sysop:sysop@db-server/seiscomp


.. _scdb_configuration:

Module Configuration
====================

| :file:`etc/defaults/global.cfg`
| :file:`etc/defaults/scdb.cfg`
| :file:`etc/global.cfg`
| :file:`etc/scdb.cfg`
| :file:`~/.seiscomp/global.cfg`
| :file:`~/.seiscomp/scdb.cfg`

scdb inherits :ref:`global options<global-configuration>`.



.. confval:: connection.requestGroup

   Type: *string*

   Define the group on scmaster to subscribe for database
   requests.


.. confval:: connection.provideGroup

   Type: *string*

   Define the group on scmaster to send database response
   messages to.


.. confval:: output.type

   Type: *string*

   Define the output database connection type.


.. confval:: output.parameters

   Type: *string*

   Define the output database connection parameters.



Command-Line Options
====================

.. program:: scdb

:program:`scdb [options]`


Generic
-------

.. option:: -h, --help

   Show help message.

.. option:: -V, --version

   Show version information.

.. option:: --config-file arg

   Use alternative configuration file. When this option is
   used the loading of all stages is disabled. Only the
   given configuration file is parsed and used. To use
   another name for the configuration create a symbolic
   link of the application or copy it. Example:
   scautopick \-> scautopick2.

.. option:: --plugins arg

   Load given plugins.

.. option:: -D, --daemon

   Run as daemon. This means the application will fork itself
   and doesn't need to be started with \&.

.. option:: --auto-shutdown arg

   Enable\/disable self\-shutdown because a master module shutdown.
   This only works when messaging is enabled and the master
   module sends a shutdown message \(enabled with \-\-start\-stop\-msg
   for the master module\).

.. option:: --shutdown-master-module arg

   Set the name of the master\-module used for auto\-shutdown.
   This is the application name of the module actually
   started. If symlinks are used, then it is the name of
   the symlinked application.

.. option:: --shutdown-master-username arg

   Set the name of the master\-username of the messaging
   used for auto\-shutdown. If \"shutdown\-master\-module\" is
   given as well, this parameter is ignored.


Verbosity
---------

.. option:: --verbosity arg

   Verbosity level [0..4]. 0:quiet, 1:error, 2:warning, 3:info,
   4:debug.

.. option:: -v, --v

   Increase verbosity level \(may be repeated, eg. \-vv\).

.. option:: -q, --quiet

   Quiet mode: no logging output.

.. option:: --component arg

   Limit the logging to a certain component. This option can
   be given more than once.

.. option:: -s, --syslog

   Use syslog logging backend. The output usually goes to
   \/var\/lib\/messages.

.. option:: -l, --lockfile arg

   Path to lock file.

.. option:: --console arg

   Send log output to stdout.

.. option:: --debug

   Execute in debug mode.
   Equivalent to \-\-verbosity\=4 \-\-console\=1 .

.. option:: --log-file arg

   Use alternative log file.


Messaging
---------

.. option:: -u, --user arg

   Overrides configuration parameter :confval:`connection.username`.

.. option:: -H, --host arg

   Overrides configuration parameter :confval:`connection.server`.

.. option:: -t, --timeout arg

   Overrides configuration parameter :confval:`connection.timeout`.

.. option:: -g, --primary-group arg

   Overrides configuration parameter :confval:`connection.primaryGroup`.

.. option:: -S, --subscribe-group arg

   A group to subscribe to.
   This option can be given more than once.

.. option:: --content-type arg

   Overrides configuration parameter :confval:`connection.contentType`.

.. option:: --start-stop-msg arg

   Set sending of a start and a stop message.

.. option:: --m, --mode arg

   scdb can either process a XML file and write it to the
   database or collect messages from scmaster.
   If connected to scmaster, the mode defines what objects
   are handled: none \(no objects at all\), notifier \(notifier
   only\) or all \(all objects whereas non\-notifier objects
   are INSERTED into the database\).


Database
--------

.. option:: --db-driver-list

   List all supported database drivers.

.. option:: -d, --database arg

   The database connection string, format:
   service:\/\/user:pwd\@host\/database.
   \"service\" is the name of the database driver which
   can be queried with \"\-\-db\-driver\-list\".

.. option:: --config-module arg

   The config module to use.

.. option:: --inventory-db arg

   Load the inventory from the given database or file, format:
   [service:\/\/]location .

.. option:: --config-db arg

   Load the configuration from the given database or file,
   format: [service:\/\/]location .

.. option:: --o, --output arg

   If connected to scmaster, this flag defines the database
   connection to use for writing. The configured application
   database connection \(as received from scmaster\) is reported
   to clients as part of a database response messages.


Import
------

.. option:: -i, --input arg

   Define the import XML file to be written to database.
   Can be provided multiple times to import multiple files.

