[influxdb] Tag values not expiring

[Alex Kopp]

Hello,

I am experimenting with InfluxDB 1.4 and I'm noticing that tag values still
show up in show tag values from "raw_data" with key=route despite some of
those values having no data points in the raw_data measurement (I have a
short two-day retention policy).

Here's roughly how I have things set up:

I have three RPs:
- Autogen (not used)
- 2_days
- 90_days

Data comes into the raw_data measurement in the 2_days RP. The data has a route
tag and a value.

Every 15 minutes, I have a kapacitor script to downsample the data and
writing the new samples into a different measurement (say data_15m) in the
90_days RP. These new samples are also tagged by route.

I'm assuming that I should be able to use show tag values from "raw_data"
with key=route to get a list of routes that have been seen over the past
2ish days, but I definitely see routes in that list that return no results
when I try to select them from the raw_data measurement.

Restarting InfluxDB seems to trigger this prune of orphaned tag values. As
such, I have two questions for the group:

1) Is this behavior intended
2) Is there a way I can trigger this pruning without having to restart
InfluxDB?