# Internal building of aggregations

**URL:** <https://discuss.elastic.co/t/internal-building-of-aggregations/105302>\
**Category:** Elasticsearch\
**Created:** [October 25, 2017, 9:34pm UTC](https://discuss.elastic.co/t/internal-building-of-aggregations/105302 "2017-10-25T21:34:04Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![thampton](https://avatars.discourse-cdn.com/v4/letter/t/c4cdca/32.png) [@thampton](https://discuss.elastic.co/u/thampton)\
**Post date:** [October 25, 2017, 9:34pm UTC](https://discuss.elastic.co/t/internal-building-of-aggregations/105302/1 "2017-10-25T21:34:04Z")

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How does Elasticsearch assemble the aggregations? During a search a list of hits are produced for each shard (if I'm understanding how it works). Are the hits for each shard aggregated at that time and then merged later, similar to how hits are merged by the coordinating node?

Thanks

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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:** [November 22, 2017, 9:34pm UTC](https://discuss.elastic.co/t/internal-building-of-aggregations/105302/2 "2017-11-22T21:34:35Z")

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