Support downsampling for /series.

[IKSIN]

Signed-off-by: Aleksey Sin asin@ozon.ru

Use-case

Grafana need to get variables from /series. It do not work when we have only downsampled data (we using other retentions for every resolutions).

Changes

Support downsampling for /series API method. Based on defaultInstantQueryMaxSourceResolution

Verification

Grafana can get data for variables.

[GiedriusS]

LGTM but could we also add a changelog entry + update the HELP string in cmd/thanos/query.go somehow so that our users would know that this applies for api/v1/series requests as well?

[GiedriusS]

I think I would be OK with this code and reusing the same parameter but let's wait a bit to hear what others think.

[bwplotka]

This is kind of weird as series does not fetch chunks... I think the fix here is to actually look up all blocks even downsampled for all series? Instead of this?

What if instead put maxSourceResolution = max.Int64`? I think that should include all series... (:
What do you think?

[GiedriusS]

This is kind of weird as series does not fetch chunks... I think the fix here is to actually look up all blocks even downsampled for all series? Instead of this?

What if instead put maxSourceResolution = max.Int64`? I think that should include all series... (:
What do you think?

Yep, we could just do this here. It would reduce the confusion for the users. 👍

[IKSIN]

This is kind of weird as series does not fetch chunks... I think the fix here is to actually look up all blocks even downsampled for all series? Instead of this?

What if instead put maxSourceResolution = max.Int64`? I think that should include all series... (:
What do you think?

Yes, I think it good idea! PR Updated)

[GiedriusS]

Should be good since we do not retrieve the chunks themselves 👍

[IKSIN]

@bwplotka Any comments?)

[bwplotka]

No. Did you check if this works? ;p @IKSIN

It looks good to me. Simple and powerful 👍

[GiedriusS]

I have tested this out - works properly and now returns all data. Thanks!