How to get the difference between the last two values in influxdb
If you are measuring traffic, probably your are writting OVS data as accumulative bytes. This is an extract of my influxdb data You can get the newest two values with the following sentence: influx -execute "SELECT value FROM packets_in WHERE dp_name='s3' AND port_name='port1' ORDER BY time DESC LIMIT 2" -database=faucet -precision=rfc3339 name: packets_in time value ---- ----- 2017-03-16T20:00:23Z 326 2017-03-16T20:00:13Z 302 If you want to get the difference between them (326-302), you need the lastest influxdb version ( here a post about how to upgrade your current version). With the DIFFERENCE command, you can do it: influx -execute "SELECT DIFFERENCE(value) * -1 FROM packets_in WHERE dp_name='s3' AND port_name='port1' ORDER BY time DESC LIMIT 1" -database=faucet -precision=rfc3339 name: packets_in time ...