I've got a small question regarding the implementation of the _ttl field.
It is written in the docs that
The current _ttl implementation is deprecated and will be replaced with a different implementation in a future version.
Will the usage of the field be changed too? And when is the estimated time these changes will be impelmented?
The migration guide might be helpful for you: https://www.elastic.co/guide/en/elasticsearch/reference/current/breaking_20_mapping_changes.html#_literal__timestamp_literal_and_literal__ttl_literal_deprecated
Quoting said guide: "The _timestamp and _ttl fields are deprecated, but will remain functional for the remainder of the 2.x series.
Instead of the _timestamp field, use a normal date field and set the value explicitly.
The current _ttl functionality will be replaced in a future version with a new implementation of TTL, possibly with different semantics, and will not depend on the _timestamp field."
Hope this helps,
You can/should use time based indices instead.