Force merge issue? through kibana

[raulk89 (Raul Kaubi)]

Hi

elastic, kibana 6.5.0

I have done some testing, in dev environment, and I have noticed something.
In kibana: management -> index management --> force merge.

It says, that default value is 1, but if I run this, then it actually does nothing, and number of segments per shard is still 9 (as it was before).

It seems to me that actually default value is:

max_num_segments
Defaults to simply checking if a merge needs to execute, and if so, executes it.
Force merge API | Elasticsearch Guide [8.11] | Elastic

So it will just check, if it needs to to something.

And for example, if I insert value lower than current_segment_per_shard and higher than 1, then it will actually still use 1, so for example:

current_segment_per_shard = 9
I do force merge through kibana on an specific index, and insert value 7
then after the force merge action, I have 1 segment per shard.

So the setting that I inserted, 7, does not make no difference.

Regards
Raul

[Marius_Dragomir]

The whole thing this does is use the forcemerge API and sends the value that you add in the input as max_num_segments. For more information on how this works in the backend, you should ask the Elasticsearch team in their forum.