Skip to main content

One Minute NiFi Tip: Calcite SQL Notes

NiFi Quick Tip on SQL

You sometimes have to cast, as fields aren't what you think they are.   I have some temperatures that are stored as string, yeah I know let's yell at who did that.   Maybe it was some lazy developer (Me?~??~?~?!!!).    Let's just cast to a type that makes sense for math and comparisons.   CAST is my friend.

WHERE CAST(temperaturef as FLOAT) > 60

Apache NiFi (and lots of other awesome projects) use Apache Calcite for queries.   So if you need some SQL help, always look here:

You can also include variables in your QueryRecord queries.

WHERE CAST(temperaturef as FLOAT) >= (CAST(${predictedTemperature} as FLOAT) - 5)

There are wildcard characters that you may need to watch.

Underscore has special meaning.  Also there often column names that are reserved words.   I got a lot of columns coming from IoT often with names like timestamp, start, end and other ones used by SQL.   Just put a `start` around it.

Watch those wildcards.

select * from flowfile where internal = false
and name not like '@_@_%' ESCAPE '@'

Popular posts from this blog

Ingesting Drone Data From DJII Ryze Tello Drones Part 1 - Setup and Practice

Ingesting Drone Data From DJII Ryze Tello Drones Part 1 - Setup and Practice In Part 1, we will setup our drone, our communication environment, capture the data and do initial analysis. We will eventually grab live video stream for object detection, real-time flight control and real-time data ingest of photos, videos and sensor readings. We will have Apache NiFi react to live situations facing the drone and have it issue flight commands via UDP. In this initial section, we will control the drone with Python which can be triggered by NiFi. Apache NiFi will ingest log data that is stored as CSV files on a NiFi node connected to the drone's WiFi. This will eventually move to a dedicated embedded device running MiniFi. This is a small personal drone with less than 13 minutes of flight time per battery. This is not a commercial drone, but gives you an idea of the what you can do with drones. Drone Live Communications for Sensor Readings and Drone Control You must connect t

Advanced XML Processing with Apache NiFi 1.9.1

Advanced XML Processing with Apache NiFi 1.9.1 With the latest version of Apache NiFi, you can now directly convert XML to JSON or Apache AVRO, CSV or any other format supported by RecordWriters.   This is a great advancement.  To make it even easier, you don't even need to know the schema before hand.   There is a built-in option to Infer Schema. The results of an RSS (XML) feed converted to JSON and displayed in a slack channel. Besides just RSS feeds, we can grab regular XML data including XML data that is wrapped in a Zip file (or even in a Zipfile in an email, SFTP server or Google Docs). Get the Hourly Weather Observation for the United States Decompress That Zip  Unpack That Zip into Files One ZIP becomes many XML files of data. An example XML record from a NOAA weather station. Converted to JSON Automagically Let's Read Those Records With A Query and Convert the results to JSON Records

New Features of Apache NiFi 1.13.0

 New Features of Apache NiFi 1.13.0 Check it out : Download today : Release Note s: Migration : New Features ListenFTP UpdateHiveTable - Hive DDL changes -Hive Update Schema ie Data Drift ie Hive Schema Migration!!!! SampleRecord - different sampling approaches to records ( Interval Sampling,  Probabilistic Sampling,  Reservoir Sampling) CDC Updates Kudu updates AMQP and MQTT Integration Upgrades ConsumeMQTT - readers and writers added HTTP access to NiFi by default is now configured to accept connections to only.  If you want to allow broader access for some reason for HTTP and you understand the security implications you can still control that as always by changing the '' pr