Changing codec for existing indexes

Elastic Stack Elasticsearch
1

We are upgrading our ES version to 6.4.2 and would set default compression to best_comrpession. Problem is that when restoring index from a snapshot, the best-compression is not applied even when explicitly setting codec for that index.

How can I compress my existing index?

2

Set the codec to best_compression for the index and the run a force merge down to a single segment. This will apply the new codec.

3

Thanks!