# Id\_cache is growing at index time, without warmers or queries being run **URL:** \ **Category:** Elasticsearch\ **Created:** [November 27, 2013, 4:43pm UTC](https://discuss.elastic.co/t/id-cache-is-growing-at-index-time-without-warmers-or-queries-being-run/14619 "2013-11-27T16:43:52Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Emilie\_Lavigne](https://avatars.discourse-cdn.com/v4/letter/e/91b2a8/32.png) [@Emilie\_Lavigne](https://discuss.elastic.co/u/Emilie_Lavigne)\ **Post date:** [November 27, 2013, 4:43pm UTC](https://discuss.elastic.co/t/id-cache-is-growing-at-index-time-without-warmers-or-queries-being-run/14619/1 "2013-11-27T16:43:52Z")
I am using 0.90.7 and am surprised to see that indexing a document with a parent document automatically increases the id\_cache by about 150b. Ie: if I run: curl -XPOST localhost:9200/avalanche-parent-child/metadata/?parent=NA -d '{"uuid":"123456789", "content": "some content"}' And then look at the id\_cache size (using curl localhost:9200/\_nodes/stats/indices?pretty), I automatically see the id\_cache size go up by about 150b even if no has\_child/has\_parent queries or warmers were run. Two questions: - What gets stored in the id\_cache in present of parent-child mappings? - Is there a way to prevent an automatic refresh of the cache after indexing a child document? - When a query with has\_child/has\_parent is run, are all child-\>parent mappings loaded into the id\_cache, or just the ones that relate to the query ran? - How long is the default expiry for the id\_cache? Is there a way to change it? My use case: I have multiple documents that are in reality orphans. When that is the case, they are added with a referenced non-existent parent called "NA". I am hoping I can prevent these documents from taking up space into the id\_cache since we do not have sufficient cache space to contain all \_ids into the id\_cache. -- 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/28efba96-2683-49b3-a70e-8b9239451254%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/28efba96-2683-49b3-a70e-8b9239451254%40googlegroups.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![mvg](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mvg/32/98890_2.png) [@mvg](https://discuss.elastic.co/u/mvg)\ **Post date:** [November 29, 2013, 10:34am UTC](https://discuss.elastic.co/t/id-cache-is-growing-at-index-time-without-warmers-or-queries-being-run/14619/2 "2013-11-29T10:34:08Z")
Hi Emilie, The id\_cache is a lookup from Lucene docId (int) to parent uid (string) for both parent and child docs. Entries of the id\_cache are coupled to a part of a Lucene index (segment) and once a segment gets cleaned up also the enty in the id\_cache gets cleaned up and this happens during merging of segments. There is no time based expiration. Also the id\_cache contains all the parent ids visible from the moment a refresh happens and never a selection for a specific has\_child query. Since version 0.90.7 ( [Better warm-up of merged segments · Issue #3819 · elastic/elasticsearch · GitHub](https://github.com/elasticsearch/elasticsearch/issues/3819)) we automatically update / create the id cache during the refresh. The reason behind this that it will prevent multiple first search request from doing the id\_cache initialisation (double work). The id\_cache needs to be there for parent/child searchers, so it is better to create / update the id\_cache in a controlled manner during the refresh. If you don't want this behaviour you can either disable the automatic refresh or disable the automatic warming that happens during a refresh. For the later you can use the `index.warmer.enabled` option and set it to false, but this also disable eager field data loading. Having a NA id will reduce the size the id\_cache needs for each document, but each document with this `NA` id needs some space in the id\_cache. I hope this explanation somewhat helps you to understand the parent/child in ES! Martijn On 27 November 2013 17:43, Emilie Lavigne [emilie.lavigne@gmail.com](mailto:emilie.lavigne@gmail.com) wrote: > I am using 0.90.7 and am surprised to see that indexing a document with a > parent document automatically increases the id\_cache by about 150b. > > Ie: if I run: > > curl -XPOST localhost:9200/avalanche-parent-child/metadata/?parent=NA -d > '{"uuid":"123456789", "content": "some content"}' > > And then look at the id\_cache size (using curl > localhost:9200/\_nodes/stats/indices?pretty), I automatically see the > id\_cache size go up by about 150b even if no has\_child/has\_parent queries > or warmers were run. > > Two questions: > > - What gets stored in the id\_cache in present of parent-child mappings? > - Is there a way to prevent an automatic refresh of the cache after > indexing a child document? > - When a query with has\_child/has\_parent is run, are all child-\>parent > mappings loaded into the id\_cache, or just the ones that relate to the > query ran? > - How long is the default expiry for the id\_cache? Is there a way to > change it? > > My use case: I have multiple documents that are in reality orphans. When > that is the case, they are added with a referenced non-existent parent > called "NA". I am hoping I can prevent these documents from taking up > space into the id\_cache since we do not have sufficient cache space to > contain all \_ids into the id\_cache. > > -- > 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/28efba96-2683-49b3-a70e-8b9239451254%40googlegroups.com](https://groups.google.com/d/msgid/elasticsearch/28efba96-2683-49b3-a70e-8b9239451254%40googlegroups.com) > . > For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). -- Met vriendelijke groet, Martijn van Groningen -- 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/CA%2BA76TwD1T6j5E8g13Lps%3DX2Bz-uS-ULDj6sqGG-wmuSSXkzbg%40mail.gmail.com](https://groups.google.com/d/msgid/elasticsearch/CA%2BA76TwD1T6j5E8g13Lps%3DX2Bz-uS-ULDj6sqGG-wmuSSXkzbg%40mail.gmail.com). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**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, 2:04am UTC](https://discuss.elastic.co/t/id-cache-is-growing-at-index-time-without-warmers-or-queries-being-run/14619/3 "2017-07-06T02:04:11Z")