1. forcemerge interface
Force segment merging, when set to 1, it is expected that there will be only 1 index segment in the end. But the actual situation is that the result of the merge is that the total number of segments will be reduced, but still greater than 1, and the command to force the merge can be executed multiple times.
The smaller the target value is set. The merge will take longer.
curl -XPOST http://127.0.0.1:9200/logstash-2015-06.10/_forcemerge?max_num_segments=1
Segment merging consumes more disk IO resources. Do not perform this operation when a large number of indexes are created or when there are many queries.