[xnx]

How does this differ from a log file?

[snissn]

I've been thinking about this question for a while. It's confusing at first blush because it's an append-only database and it has a WAL — and it feels like a WAL is already an append-only database, so what's even happening?

Looking back at the project now, I think the value comes from querying it, and especially from automatic aggregations.

    [rollups]
    enabled = true
    checkpoint_file = "rollup.checkpoints.log"
    default_grace = "5m"

    [[rollups.jobs]]
    id = "outside_temp_1h"
    source_metric = "temp.out_dry"
    interval = "1h"
    aggregates = ["min", "max", "sum", "avg", "count"]
    destination_db = "sensors_rollup_1h"
    destination_metric_prefix = "temp.out_dry"

This is a reasonable use case that can't immediately be resolved by just logging to a file. It creates an aggregation profile, so a sensor could log temperature every minute and the database will automatically average temperature by the hour. That's a straightforward and meaningful use case.

There's also some query support, but that may be closer to something you can sort of do if you just have a log file.

I think the aggregations are the most direct value proposition. OP/author: worth making this pitch "above the fold" in the README, imho.

Also, I've done a lot of analytics work, and a fun feature to add that I've built in the past is an approximate median. I might open a PR and remind myself how to build that. Cheers!

[aymanhs72]

Thanks for the reply and explanation. I added rollups to the readme file too

[leetrout]

Seems the IOT / embedded device constraint is what is driving the query feature. You don't have to go scan all of the file and depending on where it is running having the rollup functionality could be a big help

[neoyagami]

You can query it? And may be faster?

[aymanhs72]

I expect queries to be mostly around a single or few sensors around date range. There is no index but the files for live readings are daily based, and reading single day file is extremely fast. Rollups are also supported and act like normal databases with a configurable period, monthly or yearly. And those can be queried pretty fast too