# DocValues overhead in ES **URL:** \ **Category:** Elasticsearch\ **Created:** [March 25, 2015, 4:05pm UTC](https://discuss.elastic.co/t/docvalues-overhead-in-es/22897 "2015-03-25T16:05:39Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Pawel\_Rog](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/pawel_rog/32/141223_2.png) [@Pawel\_Rog](https://discuss.elastic.co/u/Pawel_Rog)\ **Post date:** [March 25, 2015, 4:05pm UTC](https://discuss.elastic.co/t/docvalues-overhead-in-es/22897/1 "2015-03-25T16:05:39Z")
Hi, I analyzed heap dump taken from Elasticsearch and I can see a lot of space in heap is occupied by structures and references related to doc values. I can see tons of hash maps with weak references pointing to objects representing some values in DV. I was wondering if this is somehow cached on ES side or it is totally Lucene internal mechanism. Can we influence the size/number of instances of objects connected to field data? I'd be glad if someone can explain it to me. -- Paweł Róg -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx\_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [March 26, 2015, 2:31am UTC](https://discuss.elastic.co/t/docvalues-overhead-in-es/22897/2 "2015-03-26T02:31:13Z")
If you have a lot of unique values and you ask for aggregations looking for unique values amongst though, then what you are seeing can happen. On 26 March 2015 at 03:05, Paweł Róg [prog88@gmail.com](mailto:prog88@gmail.com) wrote: > Hi, > I analyzed heap dump taken from Elasticsearch and I can see a lot of space > in heap is occupied by structures and references related to doc values. I > can see tons of hash maps with weak references pointing to objects > representing some values in DV. I was wondering if this is somehow cached > on ES side or it is totally Lucene internal mechanism. Can we influence the > size/number of instances of objects connected to field data? > > I'd be glad if someone can explain it to me. > > -- > Paweł Róg > > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). > To view this discussion on the web visit > [https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx\_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com) > [https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx\_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com?utm_medium=email&utm_source=footer) > . > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/CAEYi1X\_EO8N%2B1f%3D7spiQzXYp-71OhPcmT3n09pei-52cdvANrg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAEYi1X_EO8N%2B1f%3D7spiQzXYp-71OhPcmT3n09pei-52cdvANrg%40mail.gmail.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**Author:** ![Pawel\_Rog](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/pawel_rog/32/141223_2.png) [@Pawel\_Rog](https://discuss.elastic.co/u/Pawel_Rog)\ **Post date:** [March 26, 2015, 8:23am UTC](https://discuss.elastic.co/t/docvalues-overhead-in-es/22897/3 "2015-03-26T08:23:14Z")
Hi, Thank you for your response. Unfortunately I think we misunderstood. I was NOT asking if described case can happen because I see it can 🙂 I was rather asking about ES internals and if there is any way to optimize such a case (including source code modifications). -- Paweł Róg On Thursday, March 26, 2015 at 3:31:51 AM UTC+1, Mark Walkom wrote: > If you have a lot of unique values and you ask for aggregations looking > for unique values amongst though, then what you are seeing can happen. > > On 26 March 2015 at 03:05, Paweł Róg \<[pro...@gmail.com](mailto:pro...@gmail.com) \\> > wrote: > > > Hi, > > I analyzed heap dump taken from Elasticsearch and I can see a lot of > > space in heap is occupied by structures and references related to doc > > values. I can see tons of hash maps with weak references pointing to > > objects representing some values in DV. I was wondering if this is somehow > > cached on ES side or it is totally Lucene internal mechanism. Can we > > influence the size/number of instances of objects connected to field data? > > > > I'd be glad if someone can explain it to me. > > > > -- > > Paweł Róg > > > > -- > > You received this message because you are subscribed to the Google Groups > > "elasticsearch" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to [elasticsearc...@googlegroups.com](mailto:elasticsearc...@googlegroups.com) \. > > To view this discussion on the web visit > > [https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx\_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com) > > [https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx\_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com?utm\_medium=email&utm\_source=footer](https://groups.google.com/d/msgid/elasticsearch/CAHngsdhxHCDXXcx_NzcDNd%2BPnMJ%3DQigcscNXfn8kcjSCh4x3mg%40mail.gmail.com?utm_medium=email&utm_source=footer) > > . > > For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [elasticsearch+unsubscribe@googlegroups.com](mailto:elasticsearch+unsubscribe@googlegroups.com). To view this discussion on the web visit [https://groups.google.com/d/msgid/elasticsearch/1bb6b0b3-c261-4f37-b0e0-3bf537595e70%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/1bb6b0b3-c261-4f37-b0e0-3bf537595e70%40googlegroups.com). For more options, visit [https://groups.google.com/d/optout](https://groups.google.com/d/optout). ---
**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, 12:23am UTC](https://discuss.elastic.co/t/docvalues-overhead-in-es/22897/4 "2017-07-06T00:23:47Z")