SQL Historian

An SQL Historian is available as a core service. The sql historian has been programmed to allow for inconsistent network connectivity (automatic re-connection to tcp based databases). All additions to the historian are batched and wrapped within a transaction with commit and rollback functions properly implemented. This allows the maximum throughput of data with the most protection. The following example configurations show the different options available for configuring the SQL Historian Agent.

MySQL Specifics

MySQL requires a third party driver (mysql-connector) to be installed in order for it to work. Please execute the following from an activated shell in order to install it.

pip install --allow-external mysql-connector-python mysql-connector-python

In addition, the mysql database must be created and permissions granted for select, insert and update before the agent is started. In order to support timestamp with microseconds you need at least MySql 5.6.4. Please see this MySql documentation for more details The following is a minimal configuration file for using a MySQL based historian. Other options are available and are documented http://dev.mysql.com/doc/connector-python/en/connector-python-connectargs.html. Not all parameters have been tested, use at your own risk.

{
    "agentid": "sqlhistorian-mysql",
    "connection": {
        "type": "mysql",
        "params": {
            "host": "localhost",
            "port": 3306,
            "database": "volttron",
            "user": "user",
            "passwd": "pass"
        }
    }
}

Sqlite3 Specifics

An Sqlite Historian provides a convenient solution for under powered systems. The database is parameter is a location on the file system. By default it is relative to the agents installation directory, however it will respect a rooted or relative path to the database.

{
    "agentid": "sqlhistorian-sqlite",
    "connection": {
        "type": "sqlite",
        "params": {
            "database": "data/historian.sqlite",
        }
    }
}