feature request: Add support for csvq

[jftuga]

Please consider adding support for csvq. This will allow for using an SQL-like query language for CSV data.

One benefit from would include the ability to add a delta column to the CSV table using SQL LAG() or LEAD() functions.

Example:

Original CSV, named test.csv:

Date, Processed
2021-04-15, 300
2021-04-14, 275

Augmented output with csvq could then be rendered in Grafana like this:

csvq 'select Date, Processed, LAG(Processed) over (order by Date) as Previous, (Processed-Previous) as Delta from test order by Date desc'

Date	Processed	Previous	Delta
2021-04-15	300	275	25
2021-04-14	275	NULL	NULL

[marcusolsson]

Thank you for the feature request! I think this could be really useful in giving users more control over the data returned.

[HenrikRolandHansen]

This would be a nice feature instead of using filtering as suggested in #116. adding support for using variables with csvq would be handy as well.