# Questdb datasource query in Grafana alert **URL:** \ **Category:** Community\ **Created:** [February 5, 2025, 1:54pm UTC](https://community.questdb.com/t/questdb-datasource-query-in-grafana-alert/739 "2025-02-05T13:54:58Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![ajay100](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@ajay100](https://community.questdb.com/u/ajay100)\ **Post date:** [February 5, 2025, 1:54pm UTC](https://community.questdb.com/t/questdb-datasource-query-in-grafana-alert/739/1 "2025-02-05T13:54:58Z")
Hello! I am enjoying my initial experience with Questdb using more natural SQL queries vs InfluxDB. However I have been struggling with Grafana Alerts using a Questdb datasource and hope you can help. My initial aim is to send an alert from Grafana to Telegram if a device stops sending data to Questdb. A Tank1 datasource includes columns voltage and timestamp. In the QuestDb Web Console I have successfully tested this query to get the most recent 5 minutes of data: `SELECT voltage, timestamp FROM "tank1" WHERE (timestamp > dateadd('m', -5, now())) ORDER BY timestamp DESC;` If I stop the datasource logging to Questdb for greater than 5m, I get a successful response in the console, with no records returned. If I run the same query as an alert condition in Grafana when there is data, the alert is healthy and does not fire. When the data is stopped, after 5 minutes the alert changes to an error: `[sse.readDataError] [voltage] got error: no float64 value column found in frame voltage` ([voltage] is the name of the query) I have tried many variations, including changing the query to ‘Time series’, (with and without the voltage column), with different errors and alerts not working along the way. For example: `SELECT timestamp FROM "tank1" WHERE $__timeFilter(timestamp) SAMPLE BY $__sampleByInterval ALIGN TO CALENDAR ORDER BY timestamp DESC` using a time range of ‘Now -5m’ to restrict the data. This query produces the error: `[sse.readDataError] [voltage] got error: input data must be a wide series but got type not (input refid)` I want to alert on both the voltage level (\<11.5V) and ‘No Data’, but it’s not a problem if I can’t do both in one alert. Can anyone assist please? ---
**Author:** ![ajay100](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@ajay100](https://community.questdb.com/u/ajay100)\ **Post date:** [February 8, 2025, 11:05am UTC](https://community.questdb.com/t/questdb-datasource-query-in-grafana-alert/739/2 "2025-02-08T11:05:24Z")
If I have not expressed this issue in a way that makes sense, please let me know! I am using Grafana v11.4.0 and Questdb v8.2.2, both in docker. Fortunately I am logging concurrently to Influxdb and a simple query to return voltage in the last two minutes provides ‘No data’ if the data flow is stopped temporarily. ![image](https://canada1.discourse-cdn.com/flex004/uploads/questdb/original/1X/ccbc12f26e69051536afa97962adb4ebe470a8c2.png) As detecting a sensor failure is extremely important, how can this be achieved simply with Questdb in Grafana Alerts? ---
**Author:** ![nwoolmer](https://yyz2.discourse-cdn.com/flex004/user_avatar/community.questdb.com/nwoolmer/32/24_2.png) [@nwoolmer](https://community.questdb.com/u/nwoolmer)\ **Post date:** [February 8, 2025, 1:01pm UTC](https://community.questdb.com/t/questdb-datasource-query-in-grafana-alert/739/3 "2025-02-08T13:01:49Z")
Hey, thanks for your patience, will come back to you in a little bit! ---
**Author:** ![nwoolmer](https://yyz2.discourse-cdn.com/flex004/user_avatar/community.questdb.com/nwoolmer/32/24_2.png) [@nwoolmer](https://community.questdb.com/u/nwoolmer)\ **Post date:** [February 8, 2025, 8:13pm UTC](https://community.questdb.com/t/questdb-datasource-query-in-grafana-alert/739/4 "2025-02-08T20:13:44Z")
Ok, for the no data error, you could use `count()` to ensure you always get data back. Then you can match against `count == 0` for when there is no data. What type is your `voltage` column? Is it a `FLOAT`, not a `DOUBLE`? Re: wide-series error, I’m guessing this is just a confusing message referring to the fact it can’t find a numeric column to use for the alert - maybe due to a typing issue. ---
**Author:** ![ajay100](https://avatars.discourse-cdn.com/v4/letter/a/a9a28c/32.png) [@ajay100](https://community.questdb.com/u/ajay100)\ **Post date:** [February 9, 2025, 2:57pm UTC](https://community.questdb.com/t/questdb-datasource-query-in-grafana-alert/739/5 "2025-02-09T14:57:00Z")
Thank you @nwoolmer for the tip. The voltage column is a float. This rule successfully provides an alert when ‘true’, using a ‘now-2m’ time range: [voltage\_query] > SELECT count(voltage) FROM “tank1” WHERE $\_\_timeFilter(timestamp) > With math expression: > $voltage\_query==0 I experimented further and the following also works and provides both No Data and low voltage alerts (with ‘now-2m’ time range): > SELECT last(voltage) FROM “tank2” WHERE $\_\_timeFilter(timestamp) > With math expression (for 12V battery): > ${voltage\_query} \< 11.5 I’m not sure why these queries don’t produce errors like all of the others I tried! I will see what I can discover. Cheers, Andrew ---
**Author:** ![nwoolmer](https://yyz2.discourse-cdn.com/flex004/user_avatar/community.questdb.com/nwoolmer/32/24_2.png) [@nwoolmer](https://community.questdb.com/u/nwoolmer)\ **Post date:** [February 9, 2025, 2:57pm UTC](https://community.questdb.com/t/questdb-datasource-query-in-grafana-alert/739/6 "2025-02-09T14:57:59Z")
Great news! Let us know if you run into any more issues 🙂