# Shard Lucene segments single threaded? **URL:** \ **Category:** Elasticsearch\ **Created:** [February 9, 2021, 8:19am UTC](https://discuss.elastic.co/t/shard-lucene-segments-single-threaded/263696 "2021-02-09T08:19:39Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![ebuildy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ebuildy/32/6070_2.png) [@ebuildy](https://discuss.elastic.co/u/ebuildy)\ **Post date:** [February 9, 2021, 8:19am UTC](https://discuss.elastic.co/t/shard-lucene-segments-single-threaded/263696/1 "2021-02-09T08:19:39Z")
I am just curious, I know a search on 5 shards take 5 Java threads, but if each shard have 10 segments: 1. Each segments are searched synchronously ? (mean the more segments the longer is the search) 2. Each segments are search in parallel ? Thanks you, (I search arguments to recommend elasticsearch, from [Q&A from "The Great Search Engine Debate - Elasticsearch, Solr or Vespa?" Meetup | Vespa Blog](https://blog.vespa.ai/the-great-search-engine-debate-elasticsearch-solr-or-vespa/) ^^) ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [February 9, 2021, 8:55am UTC](https://discuss.elastic.co/t/shard-lucene-segments-single-threaded/263696/2 "2021-02-09T08:55:19Z")
Answer is 1. That's why having only one segment for a stable index is better. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [March 9, 2021, 8:55am UTC](https://discuss.elastic.co/t/shard-lucene-segments-single-threaded/263696/3 "2021-03-09T08:55:21Z")
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