That looks great! I love how (relatively) simple it all is to write your own logic.
One of the reasons that we added packages (bin/solr package) to Solr is so that if someone wants to add something like a java() evaluator, they can! > On Jan 4, 2022, at 11:40 AM, Damiano Albani <damiano.alb...@gmail.com> wrote: > > Hi, > > Just a quick note to mention that I've managed to implement what I wanted > in terms of non equi-joins. > Should someone be interested, I've put my code on > https://github.com/dalbani/solr-streaming-expressions. > > By the way, I happened to need a startsWith function and I implemented it > quite easily. > But I'm wondering if a very generic -- if not possibly not very safe -- > java() evaluator could be built. > That would open streaming expressions to the whole Java API instead of > having to write individual evaluators. > For the example of startsWith, it could look like something in the range of: > >> java(val(Hello), val(World), "arg0.startsWith(arg1)") > > Using say, https://www.javassist.org/, to turn the code argument into > bytecode. > What do you think? > > Regards, > > On Wed, Dec 29, 2021 at 12:39 PM Damiano Albani <damiano.alb...@gmail.com> > wrote: > >> Hello, >> >> I'm new to streaming expressions, so I'm trying to understand their >> features and limitations. >> In particular the so-called "stream operators" implementing join >> operations. >> Like "innerJoin", "leftOuterJoin", etc. >> >> I see that they support a "on" parameter, defining the *equality* check >> to be performed. >> But, coming from the SQL world, I'm used to being able to use a variety of >> comparison operators in join predicates. That is, not only equality, as in >> "equi-joins". >> >> Is there a reason why the current implementation of Solr supports >> equi-joins only? Would it be technically possible (and desired) to support >> other comparison operators with joins? >> And maybe somehow allow the use of the available stream evaluators >> <https://solr.apache.org/guide/8_11/stream-evaluator-reference.html>? >> >> To give the context of my question: I'm trying to join 2 sets of documents >> with a hierarchical relationship. >> My goal is to join them using a "path" field on one side and >> "descendent_path" field on the other side. >> But it looks like that only doc values are accessible (and not analyzed >> ones) in streams, so I suppose I'd be left with a join criteria like this >> pseudo-code: >> >>> on="starts_with(right.path, left.path)" >> >> Where, in this hypothetical example: >> >>> left.path=/categories/category1" >>> right.path=/categories/category1/sub-categories/sub-category-a" >> >> >> Or do I completely misunderstand how Solr (streams) work? ;-) >> Thanks for your help! >> >> Regards, >> >> -- >> Damiano Albani >> > > > -- > Damiano Albani _______________________ Eric Pugh | Founder & CEO | OpenSource Connections, LLC | 434.466.1467 | http://www.opensourceconnections.com <http://www.opensourceconnections.com/> | My Free/Busy <http://tinyurl.com/eric-cal> Co-Author: Apache Solr Enterprise Search Server, 3rd Ed <https://www.packtpub.com/big-data-and-business-intelligence/apache-solr-enterprise-search-server-third-edition-raw> This e-mail and all contents, including attachments, is considered to be Company Confidential unless explicitly stated otherwise, regardless of whether attachments are marked as such.
