# Performance degradation for wildcard queries from 1.5.2 to 5.2.2?

**URL:** https://discuss.elastic.co/t/performance-degradation-for-wildcard-queries-from-1-5-2-to-5-2-2/79145
**Category:** Elasticsearch
**Created:** [March 18, 2017, 7:22pm UTC](https://discuss.elastic.co/t/performance-degradation-for-wildcard-queries-from-1-5-2-to-5-2-2/79145 "2017-03-18T19:22:00Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![\_markus](https://avatars.discourse-cdn.com/v4/letter/_/ecb155/32.png) [@\_markus](https://discuss.elastic.co/u/_markus)
#### Post date: [March 18, 2017, 7:22pm UTC](https://discuss.elastic.co/t/performance-degradation-for-wildcard-queries-from-1-5-2-to-5-2-2/79145/1 "2017-03-18T19:22:00Z")

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## Summary

I'm working upgrading from 1.5.2 to 5.2.2 and I've many performance points which changed and working through them I noticed that wildcard queries especially stand out.

> FTR: I'm aware how bad wildcard, especial prefix wildcard, queries. It's currently a business requirement and I'm constantly trying to improve the queries and especially I want to get rid of them but it's not yet possible.

My tests were conducted on my local dev VM:

- ES 1.5.2 on OpenJDK 1.7.0\_121 with 2GB RAM and 1GB for ES, 2 CPUs
- ES 5.2.2 on Oracle JDK 1.8.0\_121 with 3GB RAM and 2GB for ES, 3 CPUs ; I simply increased the RAM on that machine because I realized the java XMX parameter was upped

Both versions were installed from the official ES package repositories on Ubuntu 14.04 LTS.

I tested with `siege -c <concurrency> -b -t 1m 'http://localhost:9200/alias/<Type>/_search POST <json payload>`

### With 1.5.2

Query: `{ "query": { "filtered": { "query": { "bool": { "should": [{ "wildcard": { "comment.message": { "value": "*someterm*", "boost": 1 } } }] } } } } } `

- concurrency 1 , requests per minute 20968
- concurrency 10 , requests per minute 43165
- concurrency 50 , requests per minute 42811

### With 5.2.2

Query adapted: `{ "query": { "bool": { "filter": [{ "bool": { "should": [ { "wildcard": { "comment.message": { "value": "*someterm*", "boost": 1 } } }] } } ] } } }`

- concurrency 1 , requests per minute 16759
- concurrency 10 , requests per minute 23722
- concurrency 50 , requests per minute 24472

## General information

- I tested a few of our application queries for both versions (always adapted and in some cases even optimized the queries) but I noticed that high concurrency always led to slower requests per minute for ES 5.2.2
- Another bottleneck are queries involving parent/child models; but tested is complex and time consuming and I'm not yet done with my results, but also here having the wildcards seems to be a defining factor
- I also tested ES 1.5.2 with Oracle JDK 1.8.0\_121 and the numbers were the same
- In practice I'm using wildcard matches on a few fields, not just one

## Question

- Why are wildcards slower in my tests?
- What can I do to improve performance, especially regarding increased concurrency?

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### 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: [March 18, 2017, 9:45pm UTC](https://discuss.elastic.co/t/performance-degradation-for-wildcard-queries-from-1-5-2-to-5-2-2/79145/2 "2017-03-18T21:45:19Z")

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Don't use wildcards!

Specifically queries starting with \* must be avoid

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### Author: ![\_markus](https://avatars.discourse-cdn.com/v4/letter/_/ecb155/32.png) [@\_markus](https://discuss.elastic.co/u/_markus)
#### Post date: [April 13, 2017, 6:26am UTC](https://discuss.elastic.co/t/performance-degradation-for-wildcard-queries-from-1-5-2-to-5-2-2/79145/3 "2017-04-13T06:26:03Z")

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No the answer I expected/hoped for, but yes, ultimately you're right.

I've rewritten everything which required wildcards to use ngrams. It bumped my index to 180% of it's size but queries so much faster, no doubt.

Thank you!

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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: [May 11, 2017, 6:34am UTC](https://discuss.elastic.co/t/performance-degradation-for-wildcard-queries-from-1-5-2-to-5-2-2/79145/4 "2017-05-11T06:34:54Z")

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