# Concurrent IndexSearch clarification

**URL:** <https://discuss.elastic.co/t/concurrent-indexsearch-clarification/300073>\
**Category:** Elasticsearch\
**Created:** [March 18, 2022, 4:51pm UTC](https://discuss.elastic.co/t/concurrent-indexsearch-clarification/300073 "2022-03-18T16:51:04Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dlants](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dlants/32/103223_2.png) [@dlants](https://discuss.elastic.co/u/dlants)\
**Post date:** [March 18, 2022, 4:51pm UTC](https://discuss.elastic.co/t/concurrent-indexsearch-clarification/300073/1 "2022-03-18T16:51:04Z")

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This [blog post describes concurrent query execution in Lucene](https://blog.mikemccandless.com/2019/10/concurrent-query-execution-in-apache.html) (at the `IndexSearcher` level), and claims:

> Concurrent query execution is a surprisingly little known sleeper feature in Lucene, since it is not yet exposed in [Elasticsearch](https://www.elastic.co/products/elasticsearch) nor [Solr](https://lucene.apache.org/solr), two popular distributed search applications that build on Lucene. Their concurrency model is instead concurrent search across index shards (usually on different servers) for a single query, but using single-threaded search within each shard.

Is that still true (the blog post is from 2019)? Is there anything written about this in detail - how does a shard process a search, and handle querying across multiple segments?

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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:** [April 15, 2022, 4:51pm UTC](https://discuss.elastic.co/t/concurrent-indexsearch-clarification/300073/2 "2022-04-15T16:51:57Z")

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