# Facets Refactor **URL:** \ **Category:** Elasticsearch\ **Created:** [February 27, 2013, 1:53am UTC](https://discuss.elastic.co/t/facets-refactor/10916 "2013-02-27T01:53:32Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![mattweber](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mattweber/32/44940_2.png) [@mattweber](https://discuss.elastic.co/u/mattweber)\ **Post date:** [February 27, 2013, 1:53am UTC](https://discuss.elastic.co/t/facets-refactor/10916/1 "2013-02-27T01:53:32Z")
Can you please provide some information on the faceting refactor? What does "collector" and "post" modes do and when would you use one over the other? -- Thanks, Matt Weber -- 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:** ![Ivan](https://avatars.discourse-cdn.com/v4/letter/i/df788c/32.png) [@Ivan](https://discuss.elastic.co/u/Ivan)\ **Post date:** [February 27, 2013, 2:55am UTC](https://discuss.elastic.co/t/facets-refactor/10916/2 "2013-02-27T02:55:17Z")
There was no mention of the facet refactoring in the 0.90 Beta release notes. The commits are there, hopefully so more details will emerge. -- Ivan On Tue, Feb 26, 2013 at 5:53 PM, Matt Weber [matt@mattweber.org](mailto:matt@mattweber.org) wrote: > Can you please provide some information on the faceting refactor? > What does "collector" and "post" modes do and when would you use one > over the other? > > -- > Thanks, > Matt Weber > > -- > 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). -- 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:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [February 28, 2013, 8:01am UTC](https://discuss.elastic.co/t/facets-refactor/10916/3 "2013-02-28T08:01:51Z")
Hi, the first phase of the refactoring is included in 0.90. We have decided to move the second phase to post 0.90 because we wanted to get the version out. If you are a custom facet developer, the first phase doesn't break too much. In FacetExecutor, you now need to implement the collection of facets by implementing the #collector method (we have abstracted it away). The new mode (which we keep internal for now), allow to control if the facets will be executed as part of the query execution while it "collects" hits, or as a post phase, on the aggregated hits. This is implemented automatically on top of the collector implementation. On Feb 27, 2013, at 2:53 AM, Matt Weber [matt@mattweber.org](mailto:matt@mattweber.org) wrote: > Can you please provide some information on the faceting refactor? > What does "collector" and "post" modes do and when would you use one > over the other? > > -- > Thanks, > Matt Weber > > -- > 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). -- 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:** ![Mohammady\_Mahdy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mohammady_mahdy/32/2128_2.png) [@Mohammady\_Mahdy](https://discuss.elastic.co/u/Mohammady_Mahdy)\ **Post date:** [March 5, 2013, 9:17am UTC](https://discuss.elastic.co/t/facets-refactor/10916/4 "2013-03-05T09:17:25Z")
Is there a good place for someone to start learning custom facet development? On Thursday, February 28, 2013 12:01:51 PM UTC+4, kimchy wrote: > Hi, the first phase of the refactoring is included in 0.90. We have > decided to move the second phase to post 0.90 because we wanted to get the > version out. > > If you are a custom facet developer, the first phase doesn't break too > much. In FacetExecutor, you now need to implement the collection of facets > by implementing the #collector method (we have abstracted it away). > > The new mode (which we keep internal for now), allow to control if the > facets will be executed as part of the query execution while it "collects" > hits, or as a post phase, on the aggregated hits. This is implemented > automatically on top of the collector implementation. > > On Feb 27, 2013, at 2:53 AM, Matt Weber \<[ma...@mattweber.org](mailto:ma...@mattweber.org) \\> > wrote: > > > Can you please provide some information on the faceting refactor? > > What does "collector" and "post" modes do and when would you use one > > over the other? > > > > -- > > Thanks, > > Matt Weber > > > > -- > > 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) \. > > For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). -- 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:** ![Ivan](https://avatars.discourse-cdn.com/v4/letter/i/df788c/32.png) [@Ivan](https://discuss.elastic.co/u/Ivan)\ **Post date:** [March 5, 2013, 8:19pm UTC](https://discuss.elastic.co/t/facets-refactor/10916/5 "2013-03-05T20:19:01Z")
If possible, I would wait for the refactor. Right now, there are a lot of boilerplate classes that need to be created for a custom facet. For starters, looks at the terms facets classes such as TermsStringFacetCollector/TermsIntFacetCollector and the helper classes TermsFacetProcesser/Builder. -- Ivan On Tue, Mar 5, 2013 at 1:17 AM, Mo [mohammady.mahdy@gmail.com](mailto:mohammady.mahdy@gmail.com) wrote: > Is there a good place for someone to start learning custom facet > development? > > On Thursday, February 28, 2013 12:01:51 PM UTC+4, kimchy wrote: > > > Hi, the first phase of the refactoring is included in 0.90. We have > > decided to move the second phase to post 0.90 because we wanted to get the > > version out. > > > > If you are a custom facet developer, the first phase doesn't break too > > much. In FacetExecutor, you now need to implement the collection of facets > > by implementing the #collector method (we have abstracted it away). > > > > The new mode (which we keep internal for now), allow to control if the > > facets will be executed as part of the query execution while it "collects" > > hits, or as a post phase, on the aggregated hits. This is implemented > > automatically on top of the collector implementation. > > > > On Feb 27, 2013, at 2:53 AM, Matt Weber [ma...@mattweber.org](mailto:ma...@mattweber.org) wrote: > > > > > Can you please provide some information on the faceting refactor? > > > What does "collector" and "post" modes do and when would you use one > > > over the other? > > > > > > -- > > > Thanks, > > > Matt Weber > > > > > > -- > > > 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](http://googlegroups.com). > > > For more options, visit [https://groups.google.com/\*\*groups/opt\_out](https://groups.google.com/**groups/opt_out)[https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). > > > > > > > > > -- > > 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). -- 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:** ![Mohammady\_Mahdy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mohammady_mahdy/32/2128_2.png) [@Mohammady\_Mahdy](https://discuss.elastic.co/u/Mohammady_Mahdy)\ **Post date:** [March 6, 2013, 11:37am UTC](https://discuss.elastic.co/t/facets-refactor/10916/6 "2013-03-06T11:37:29Z")
Thank you for the advice/ reply. I did look there. I am not however familiar with the primitives used, things like field caches or cache recycler or what an index reader really does. I was just wondering if there is a resource that has a walk through or a more detailed description of what are the best practices or why are things that are currently implemented done the way they are? I am doing it from the basics now by getting to know lucene better then will delve in the ES code base Many thanks to you once more! On Wednesday, March 6, 2013 12:19:01 AM UTC+4, Ivan Brusic wrote: > If possible, I would wait for the refactor. Right now, there are a lot of > boilerplate classes that need to be created for a custom facet. > > For starters, looks at the terms facets classes such > as TermsStringFacetCollector/TermsIntFacetCollector and the helper classes > TermsFacetProcesser/Builder. > > -- > Ivan > > On Tue, Mar 5, 2013 at 1:17 AM, Mo \<[mohamma...@gmail.com](mailto:mohamma...@gmail.com) \\>wrote: > > > Is there a good place for someone to start learning custom facet > > development? > > > > On Thursday, February 28, 2013 12:01:51 PM UTC+4, kimchy wrote: > > > > > Hi, the first phase of the refactoring is included in 0.90. We have > > > decided to move the second phase to post 0.90 because we wanted to get the > > > version out. > > > > > > If you are a custom facet developer, the first phase doesn't break too > > > much. In FacetExecutor, you now need to implement the collection of facets > > > by implementing the #collector method (we have abstracted it away). > > > > > > The new mode (which we keep internal for now), allow to control if the > > > facets will be executed as part of the query execution while it "collects" > > > hits, or as a post phase, on the aggregated hits. This is implemented > > > automatically on top of the collector implementation. > > > > > > On Feb 27, 2013, at 2:53 AM, Matt Weber [ma...@mattweber.org](mailto:ma...@mattweber.org) wrote: > > > > > > > Can you please provide some information on the faceting refactor? > > > > What does "collector" and "post" modes do and when would you use one > > > > over the other? > > > > > > > > -- > > > > Thanks, > > > > Matt Weber > > > > > > > > -- > > > > 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](http://googlegroups.com). > > > > For more options, visit [https://groups.google.com/\*\*groups/opt\_out](https://groups.google.com/**groups/opt_out)[https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). > > > > > > > > > > > > > -- > > > 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) \. > > > For more options, visit [https://groups.google.com/groups/opt\_out](https://groups.google.com/groups/opt_out). -- 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:** ![jprante](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jprante/32/44941_2.png) [@jprante](https://discuss.elastic.co/u/jprante)\ **Post date:** [March 6, 2013, 1:53pm UTC](https://discuss.elastic.co/t/facets-refactor/10916/7 "2013-03-06T13:53:23Z")
I will try to sum it up in a few sentences from what I understand so far... Facets are a well-known feature of search engines that can return voluminous result sets, in order to let users decide how to proceed with their query. One decision may be to refine the query to filter out only parts of the result set. By assisting the user to refine the search without knowing the subtleties of a query language, facets are a most comfortable way for a search product to offer UI actions to filter result sets. Facets need to display additional information, most of statistical nature, to give the required information to the user so an educated guess can be made. In Elasticsearch, the facets are implemented as part of the search module in package org.elastisearch.search and cover a broad range of different approaches how result sets can be statstically analyzed (counting, histogram, geo, ...). They operate on field cache data in order to be fast. The process is an evaluation by a scatter/gather algorithm (or map/reduce-style) that works in several stages: first send out facet criteria, then aggregate the data in the result set, and finally collect them into a small handy reduced data structure that can be represented as part of the search response. This process works on several layers, on shard layer, and on node layer, on one or more indices. The facet implementation of Elasticsearch is now refactored to allow better customization in the implementations. Right now, only "static" facet execution is possible, and unfortunately, some of the facet code is tied to other code in Elasticsearch. Igor Motov wrote a facet with powerful scripting capabilities [GitHub - imotov/elasticsearch-facet-script: Fully Scriptable Facets for ElasticSearch](https://github.com/imotov/elasticsearch-facet-script) to demonstrate how facet execution phases could be customized. With the new framework, plugin authors will be enabled to program new algorithms to create facets, also on custom data types, by implementing custom "executors" that can operate on the data in the map/reduce phases, just like they want... So, in the future, you will see a standard set of facet implementations in the Elasticsearch core, and in plugins, you will see how Elasticsearch extensions can also introduce new kinds of facets, with a minimum of boilerplate code. Jörg Am 06.03.13 12:37, schrieb Mo: > I was just wondering if there is a resource that has a walk through or > a more detailed description of what are the best practices or why are > things that are currently implemented done the way they are? -- 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, 2:48am UTC](https://discuss.elastic.co/t/facets-refactor/10916/8 "2017-07-06T02:48:05Z")