How do you get the ElasticSearch `refresh_interval` for an index?

Question

After reading some Elasticsearch index tuning guides like How to Maximize Elasticsearch Index Performance and elastic's Tune for indexing speed I wanted to take a look at updating the refresh_interval.

We are using AWS Elasticsearch domains (elasticsearch version 6.2). There's no mention of refresh_interval on Cloudformation's doc site AWS::Elasticsearch::Domain

So I wanted to see what the default setting was for AWS Elasticsearch. Using the _settings API doesn't show the refresh_interval.

GET /my_index/_settings

And specifying the refresh_interval doesn't show anything either.

GET /my_index/_settings/index.refresh_interval

Only returns an empty object.

{}

How can I find the current refresh_interval for Elasticsearch?

Answer 1

You need to add a parameter called include_defaults in order to also retrieve the default values:

GET /my_index/_settings?include_defaults=true

In the response, you'll get a defaults section which includes the default value of the refresh_interval setting, most probably 1s.

NOTE: The reason the refresh_interval is empty is because your index has not set the value explicitly and so your index uses the default value.