InfluxDB makes indexes on all “tags” and holds both data and indexes in memory. So memory usage can be really high if you have a lot of tags and/or these tags have a lot of unique values.

Generally it is a bad idea to put into tag some numeric values – it is highly probable almost every value will be unique which means:

  • inserts will take a lot of additional memory because InfluxDB will reindex values
  • resulting index on such a tag will be very big
  • also data expiration (if set) will mean big changes in an index