Crate Historian¶
Crate is an open source SQL database designed on top of a No-SQL design. It allows automatic data replication and self-healing clusters for high availability, automatic sharding, and fast joins, aggregations and sub-selects.
Find out more about crate from https://crate.io/.
Prerequisites¶
1. Crate Database¶
For Arch Linux, Debian, RedHat Enterprise Linux and Ubuntu distributions there is a dead simple installer to get crate up and running on your system.
sudo bash -c "$(curl -L https://try.crate.io)"
This command will download and install all of the requirements for running crate, create a crate user and install a crate service. After the installation the service will be available for viewing at http://localhost:4200 by default.
Note
There is no authentication support within crate.
2. Crate Driver¶
There is a python library for crate that must be installed in the volttron python environment in order to access crate. From an activated environment, in the root of the volttron folder, execute the following command:
python bootstrap.py --crate
or
python bootstrap.py --crate
or
pip install crate
Configuration¶
Because there is no authorization to access a crate database the configuration for the CrateHistorian is very easy.
{
"connection": {
"type": "crate",
# Optional table prefix defaults to historian
"schema": "testing",
"params": {
"host": "localhost:4200"
}
}
}
Finally package, install and start the CrateHistorian agent.
See also
Agent Development Walkthrough