# What will happen if I set a small indices.fielddata.cache.size?

**URL:** <https://discuss.elastic.co/t/what-will-happen-if-i-set-a-small-indices-fielddata-cache-size/14252>\
**Category:** Elasticsearch\
**Created:** [November 4, 2013, 10:09pm UTC](https://discuss.elastic.co/t/what-will-happen-if-i-set-a-small-indices-fielddata-cache-size/14252 "2013-11-04T22:09:51Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Andrew\_Ochsner](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/andrew_ochsner/32/1287_2.png) [@Andrew\_Ochsner](https://discuss.elastic.co/u/Andrew_Ochsner)\
**Post date:** [November 4, 2013, 10:09pm UTC](https://discuss.elastic.co/t/what-will-happen-if-i-set-a-small-indices-fielddata-cache-size/14252/1 "2013-11-04T22:09:51Z")

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Hello:

I have a cluster that's encountering memory pressure. It's predominantly  
tuned for write performance (logs). Occasionally we get a query sent in  
that sorts the entire dataset by timestamp which explodes our fielddata  
cache size. It doesn't lead to OOM errors, but a lot of GC churn so we  
have to go in and manually clear the fielddata caches. I want to set the  
indices.fielddata.cache.size to something (let's say 30% for the sake of  
argument). My question is... what will happen if the size of the fielddata  
cache required for that query is more than the 30% I've allocated for the  
node? Initial tests seem to indicate that things "just work" (I get a  
response that looks valid, the caches are kept in check, etc) but I can't  
really validate that the results are properly sorted etc (too much data).

I know we really need more memory and/or more nodes. Just thought I'd ping  
the experts if they know for sure what to expect....

Thanks!  
Andy O

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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:** [July 6, 2017, 2:08am UTC](https://discuss.elastic.co/t/what-will-happen-if-i-set-a-small-indices-fielddata-cache-size/14252/2 "2017-07-06T02:08:58Z")

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