# What do we mean by OPEN Index

**URL:** <https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811>\
**Category:** Elasticsearch\
**Created:** [March 8, 2016, 5:20pm UTC](https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811 "2016-03-08T17:20:00Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![soodlikesjava](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@soodlikesjava](https://discuss.elastic.co/u/soodlikesjava)\
**Post date:** [March 8, 2016, 5:20pm UTC](https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811/1 "2016-03-08T17:20:00Z")

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Can anyone tell me what do we mean by OPEN Index , does it mean that Index is loaded in RAM and also stored in Disk . And how it behaves at Shard level . Will all the shards of the Index opened in RAM for the OPENED Index?

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**Author:** ![jpountz](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jpountz/32/45836_2.png) [@jpountz](https://discuss.elastic.co/u/jpountz)\
**Post date:** [March 8, 2016, 5:35pm UTC](https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811/2 "2016-03-08T17:35:00Z")

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OPEN means that the index is ready to serve queries. It will use some file handles and memory, but this amount of memory is much less than the size of your data.

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**Author:** ![soodlikesjava](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@soodlikesjava](https://discuss.elastic.co/u/soodlikesjava)\
**Post date:** [March 8, 2016, 5:37pm UTC](https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811/3 "2016-03-08T17:37:31Z")

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Thanks for the response , so i cannot consider that if shard is having 30 GB data , it would need 30 GB RAM to complete the Search on that Shard ? Is the understanding correct as it would be using less memory

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**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\
**Post date:** [March 9, 2016, 8:54pm UTC](https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811/4 "2016-03-09T20:54:44Z")

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> so i cannot consider that if shard is having 30 GB data , it would need 30 GB RAM to complete the Search on that Shard ?

No, it's not that simple.

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**Author:** ![soodlikesjava](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@soodlikesjava](https://discuss.elastic.co/u/soodlikesjava)\
**Post date:** [March 13, 2016, 11:57pm UTC](https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811/5 "2016-03-13T23:57:13Z")

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Can you please share me any documentation which explains how shards utilize Heap on indexing/searching?

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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:** [July 5, 2017, 11:08pm UTC](https://discuss.elastic.co/t/what-do-we-mean-by-open-index/43811/6 "2017-07-05T23:08:48Z")

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