# Do parent/child queries use BlockJoinQuery? **URL:** \ **Category:** Elasticsearch\ **Created:** [March 15, 2013, 9:04pm UTC](https://discuss.elastic.co/t/do-parent-child-queries-use-blockjoinquery/11172 "2013-03-15T21:04:26Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![q42jaap](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/q42jaap/32/2241_2.png) [@q42jaap](https://discuss.elastic.co/u/q42jaap)\ **Post date:** [March 15, 2013, 9:04pm UTC](https://discuss.elastic.co/t/do-parent-child-queries-use-blockjoinquery/11172/1 "2013-03-15T21:04:26Z")
Hi there, Do parent/child queries use BlockJoinQuery? I suppose they don't, because the has\_parent/has\_child filters/queries note that the whole \_id list is needed to be kept in memory. The only consideration is that they need to be in the same shard (I asked this earlier on this list and this was confirmed by Martijn v G). Thanks, Jaap -- 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). For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). ---
**Author:** ![simonw\_2](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/simonw_2/32/1130_2.png) [@simonw\_2](https://discuss.elastic.co/u/simonw_2)\ **Post date:** [March 16, 2013, 8:44am UTC](https://discuss.elastic.co/t/do-parent-child-queries-use-blockjoinquery/11172/2 "2013-03-16T08:44:29Z")
On Friday, March 15, 2013 10:04:26 PM UTC+1, Jaap Taal wrote: > Hi there, > > Do parent/child queries use BlockJoinQuery? this is used by nested documents not by parent/child > **[Elasticsearch Platform — Find real-time answers at scale](https://www.elastic.co)** > > Power insights and outcomes with the Elasticsearch Platform and AI. See into your data and find answers that matter with enterprise solutions designed to help you build, observe, and protect. Try Elasticsearch free today. simon > I suppose they don't, because the has\_parent/has\_child filters/queries > note that the whole \_id list is needed to be kept in memory. > The only consideration is that they need to be in the same shard (I asked > this earlier on this list and this was confirmed by Martijn v G). > > Thanks, > Jaap -- 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). 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, 2:46am UTC](https://discuss.elastic.co/t/do-parent-child-queries-use-blockjoinquery/11172/3 "2017-07-06T02:46:10Z")