Convert TAG to FIELD in InfluxDB

问题

Is it possible to convert a tag (which is string) to make field (like double) which would contain a transformed version of the tag value? Like an QL update expression?

回答1:

One could use influx_inspect export to dump the database in the line protocol format. Then relevant columns could be grepped and modified with your favorite tool, like python or sed/bash. And the modified time series could be re-inserted directly into the database (one could use split -l 7000 to split field time series into chunks and the use curl -POST .../write?db=... --data-binary @chunk and iterate over those chunks expecting HTTP 204 for correctly inserted values).

回答2:

This is only possibly using Kapacitor

stream()
  |from()
    .measurement('mymeasurement')
  |log() // outputs the current state of the pipelie
  |eval(lambda: float("mytag"))
    .as('myfield')
    .keep()
  |log()

来源：https://stackoverflow.com/questions/42392682/convert-tag-to-field-in-influxdb