table inside a database query using PromQL (in Grafana)?

[hvisage]

busy testing, and evaluating, pushing data from unbound using telegraf to database DNS into table unbound.

I got the following SQL: SELECT "ts","total_num_queries" FROM dns."unbound" ORDER BY "ts" DESC LIMIT 100;

Q1: How do I present that in PromQL?

Q2: And in Grafana using PromQL/Prometheus plugin? Sofar I can't see that total_num_queries in the Grafana query builder's explorer?

[sunng87]

Hello @hvisage , typically we use promql over prometheus compatible data source because it's more natural to run those queries. So if you are familiar with promql, I would recommend you to switch from telegraf to a prometheus based data source.

But don't worry, you can still use promql over these custom tables. You only need to do some customization because:

1. you have a custom database
2. you have a named data field

So the promql will look like

unbound{__database__="dns", __field__="total_num_queries"}

Docs for our extension to promql: https://docs.greptime.com/user-guide/query-data/promql/#greptimedbs-extensions-to-promql

[hvisage]

I would recommend you to switch from telegraf to a prometheus based data source.

too many INbound firewall rules to open up to handle prometheus PULL while with telegraf's PUSH is more "natural" to flow it from one collector to the next to the end DB and the best part, I'm using Telegraf to feed TimescaleDB, VictoriaMetrics and Greptime at the same time while testing. Telegraf shouldn't make a difference in the end results/queries, does it?

You only need to do some customization because:

1. you have a custom database
2. you have a named data field

Actually, I have multiple databases with named fields/tables as I'm busy FAFO to get the needed stuff imported and split out.
The first ones are unbound and linux (data from Telegraf) and ProxMox with NetData and firewall SNMP data next in line while we do some R&D to get Mendix+ JMX+ PostgreSQL databases/tables for those stacks.

So yes, I expect multiple DBs and tables/fields to split things till I get the right setup and understandings on which TSDB to pick ;)

[sunng87]

No problem. You can use the promql query like I provided for you to query telegraf, multi-database data. We have already covered this use case.

By the way, I believe you sent us feedback from our website and I have already replied with email if you missed it.