# Elasticsearch index\_prefixes usage

**URL:** https://discuss.elastic.co/t/elasticsearch-index-prefixes-usage/230999
**Category:** Elasticsearch
**Created:** [May 4, 2020, 3:57pm UTC](https://discuss.elastic.co/t/elasticsearch-index-prefixes-usage/230999 "2020-05-04T15:57:33Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![CSharpBender](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/csharpbender/32/50377_2.png) [@CSharpBender](https://discuss.elastic.co/u/CSharpBender)
#### Post date: [May 4, 2020, 3:57pm UTC](https://discuss.elastic.co/t/elasticsearch-index-prefixes-usage/230999/1 "2020-05-04T15:57:34Z")

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Hi,

I've read that _index\_prefixes_ can improve prefix queries but it's not clear how I should use it. Is there a way to see the generated .\_index\_prefix field values, it doesn't appear when using the \_mapping api?  
I'm using multi fields:

```auto
  "title" : {
              "type" : "text",
              "fields" : {
                "keyword" : {
                  "type" : "keyword",
                  "ignore_above" : 256,
                  "normalizer" : "lowercase_normalizer"
                },
                "words" : {
                  "type" : "text",
                  "analyzer" : "standard"
                }
              },
              "analyzer" : "edge_ngram_analyzer",
              "search_analyzer" : "standard"
            }

```

I'm using prefix query on title.keyword which is basically the lowercase raw string. What should I change to benefit from _index\_prefixes_?  
Should I specify in the query that I want to use the _\_index\_prefix_ field? How do I deal with queries longer than 19 chars?

---

<div class="post-metadata">

### Author: ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)
#### Post date: [June 1, 2020, 3:57pm UTC](https://discuss.elastic.co/t/elasticsearch-index-prefixes-usage/230999/2 "2020-06-01T15:57:44Z")

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