# Force\_merge confusion in documentation

**URL:** <https://discuss.elastic.co/t/force-merge-confusion-in-documentation/162197>\
**Category:** Elasticsearch\
**Created:** [December 27, 2018, 4:58am UTC](https://discuss.elastic.co/t/force-merge-confusion-in-documentation/162197 "2018-12-27T04:58:34Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![renjith\_ravindran](https://avatars.discourse-cdn.com/v4/letter/r/5f9b8f/32.png) [@renjith\_ravindran](https://discuss.elastic.co/u/renjith_ravindran)\
**Post date:** [December 27, 2018, 4:58am UTC](https://discuss.elastic.co/t/force-merge-confusion-in-documentation/162197/1 "2018-12-27T04:58:34Z")

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As per this link [https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-update-settings.html](https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-update-settings.html), after resetting refresh\_interval, force\_merge call is recommended. But this page([https://www.elastic.co/guide/en/elasticsearch/reference/master/indices-forcemerge.html](https://www.elastic.co/guide/en/elasticsearch/reference/master/indices-forcemerge.html)) says ' Force merge should only be called against **read-only indices**.  
So which one is correct in the case of an index where we are bulk loading some data and it is then updated daily?  
or does it mean that after the bulk\_update, we should do force\_merge, and while force\_merge is in progress, we should not attempt to write to index? And after force\_merge completes, we can start writes again

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**Author:** ![Christian\_Dahlqvist](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/christian_dahlqvist/32/4617_2.png) [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)\
**Post date:** [December 27, 2018, 9:28am UTC](https://discuss.elastic.co/t/force-merge-confusion-in-documentation/162197/2 "2018-12-27T09:28:36Z")

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Forcemerge is an expensive operation and some of the benefits are lost once data is added or modified. This is why it is recommended to only use it on indices no longer written to. If you periodically update your index you could end up doing a lot of processing for relatively little gain. Whether this is worth it or not will depend on your use case.

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**Author:** ![renjith\_ravindran](https://avatars.discourse-cdn.com/v4/letter/r/5f9b8f/32.png) [@renjith\_ravindran](https://discuss.elastic.co/u/renjith_ravindran)\
**Post date:** [December 27, 2018, 11:40am UTC](https://discuss.elastic.co/t/force-merge-confusion-in-documentation/162197/3 "2018-12-27T11:40:01Z")

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Could you please explain or link the benefits which can be achieved using force\_merge? And how is it lost if we write more data?

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [January 24, 2019, 11:40am UTC](https://discuss.elastic.co/t/force-merge-confusion-in-documentation/162197/4 "2019-01-24T11:40:09Z")

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