i see the doc have setting with the indices about force merege index.merge.scheduler.max_merge_count index.merge.scheduler.max_thread_count
with not ssd the docs give index.merge.scheduler.max_thread_count to "1" ,and the index.merge.scheduler.max_merge_count aslo need set to 1
I'm not sure what your question is, but you'll find the documentation about _forcemerge and its request parameters here.
In general Elasticsearch will handle its own segment merging well, but it's sometimes useful to trigger a forcemerge as it will expunge deleted documents when merging two segments into one and therefore save you disk space.
But note that _forcemerge should not be called on an active index as that may result in huge (>5G) segments that will usually never be merged again and therefore could build up many deleted documents if that shard is still being updated.
about the this i want to know about which number is better as flow "index.merge.scheduler.max_merge_count": "20", "index.merge.scheduler.max_thread_count": "2"
i want to know ,use kibana search the index before _forcemerge?max_num_segments=1 is good or after forcemerge?
and the max_num_segments can set as "2" or other greater than 1 number ,which is better for search index data?