Support tag expressions in storage-{aggregations,schemas}.conf

[shanson7]

With tag support in metrictank, there may be different retention/aggregations based on tag values, not just names. For instance, longer retention for prod data.

[woodsaj]

I think this needs to be done in https://github.com/graphite-project/carbon first. @DanCech

[DanCech]

You can do it today by using a pattern like ;tag=value, or if you want to match multiple tags ;tagA=value(;.+)*;tagB=value

[shanson7]

Ok, then MT would just need to pass path instead of def.Name here on these 2 lines:

metrictank/idx/memory/memory.go

Lines 353 to 356 in 36db80f

	path := def.NameWithTags()
	schemaId, _ := mdata.MatchSchema(def.Name, def.Interval)
	aggId, _ := mdata.MatchAgg(def.Name)

[shanson7]

With the caveat that this could definitely break existing patterns (for tagged time-series)

[DanCech]

It'll also make it match the carbon behavior, so I think it's the right thing to do.

[Dieterbe]

With the caveat that this could definitely break existing patterns (for tagged time-series) [in MT]

not a concern, since tagging in MT is still beta.
this change is probably something that should have gone with #806 (but in lieu of that, can be added now I think)
@replay any thoughts?

[replay]

That makes sense to me as @shanson7 described it, mdata.MatchAgg() would just need to get path instead of def.Name