Tags in loki are things like host, application, and environment. When searching by those tags and a time interval, it will read everything from disk. So any query that filters by ex. SessionId or a keyword from the log like Exception will read all the logs from disk. This can take ages if you have a lot of logs and a big time frame. Compare that with Elasticsearch which can index anyrhing, like SessionId/log message and return the result in an instant, without even reading the disk.

> When searching by those tags and a time interval, it will read everything from disk

That's what I'm asking, actually. Isn't Loki's proposition that it only indexes the tags and time interval? Do you mean that even filtering by that there's still a lot of data to go through?

Because it seems like you're saying it always fetches everything from disk.

> Isn't Loki's proposition that it only indexes the tags and time interval? Do you mean that even filtering by that there's still a lot of data to go through?

Yes

> Because it seems like you're saying it always fetches everything from disk.

If you specify a tag, like environment, it will not read the disk for data from other environments. But the tags like environment/host/timeframe are not enough if you want to query for something like error/exception/sessionid, and you might have to wait minutes/hours for a query which covers a lot of data.