Databases for Sensor Data in Python

Here are some options to persistently store sensor data in a database using python.

Anydbm

For simple key-value pairs the anydbm module looks the best.

It stores values as strings. Because of this you may need to use another module called pickle to convert non-string values into strings.

For example:

import anydbm, pickle
from datetime import datetime

#Open a database - if it doesn't exist: create it
db = anydbm.open('test_data.db', 'c')

time_now_in = datetime.now()
string_version_in = pickle.dumps(time_now_in)

#Store value
db['1'] = string_version_in
#Close database
db.close()

#Open database
db2 = anydbm.open('test_data.db')

string_version_out = db2['1']
time_now_out = pickle.loads(string_version_out)
print time_now_out

db2.close()

SQLite

For more advanced database features the next step is sqlite3.

A tutorial on sqlite3 can be found here.

You may need to install sqlite3:

sudo apt-get install sqlite3

Then in python you can use SQL statements using code such as:

import sqlite3 as lite

#... - data in variables

# Set up a new database connection - db will be created if it doesn't exist
con = lite.connect('energymonitor.db')

#with the db connection (simplifies commit etc)
with con:

cur = con.cursor()

#Create a READINGS table if it doesn't already exist
cur.execute('CREATE TABLE IF NOT EXISTS readings (r_datetime TIMESTAMP, r_watts INT, r_temp INT)')

#Store sensor readings
cur.execute('INSERT INTO readings VALUES(?,?,?)', (time, watts, temp))

This then stores my energy monitor readings in a database called (unoriginally) "readings":