Here are the docs on it: Database management using InfluxQL | InfluxDB OSS 1.7 Documentation But it all depends on how much data you are writing to the DB. If you are writing a lot of data – your shards will be large – you’ll want the duration shorter.
It’s really a function of how long your retention policy is, and how much data is in each shard, based on the data ingestion rate.
dg
