[FEATURE] Support for KNNQueryBuilder

[kannangce]

Is your feature request related to a problem?

When composing queries using multiple querybuilders, we need a KNNQueryBuilder.

What solution would you like?

KNNQueryBuilder extending org.opensearch.index.query.AbstractQueryBuilder needs to be added.

What alternatives have you considered?

• There is an old issue for the same in which knn support has been added without the KNNQueryBuilder .
• There are suggestions to use knn-plugin. But the plugin is packaged as zip and not usable as a java library.
• At the moment created a copy class following this and making it work. But a permenant solution would be a KNNQueryBuilder class.

[dblock]

@kannangce Makes sense, would you like to try and contribute this?

[Xtansia]

opensearch-java contains its own versions of the query classes and builder types for its particular API design, and does not use AbstractQueryBuilder which originates from OpenSearch core/server: https://github.com/opensearch-project/OpenSearch/blob/main/server/src/main/java/org/opensearch/index/query/AbstractQueryBuilder.java

Could you share more about what you're trying to achieve, otherwise your request may be better suited for discussing on the k-NN plugin repository how best to re-use the KNNQueryBuilder class.

[kannangce]

@kannangce Makes sense, would you like to try and contribute this?

Sure!

[kannangce]

@Xtansia ,

Thanks a lot for the response!

opensearch-java contains its own versions of the query classes and builder types for its particular API design, and does not use AbstractQueryBuilder which originates from OpenSearch core/server: https://github.com/opensearch-project/OpenSearch/blob/main/server/src/main/java/org/opensearch/index/query/AbstractQueryBuilder.java

Makes sense.

Could you share more about what you're trying to achieve, otherwise your request may be better suited for discussing on the k-NN plugin repository how best to re-use the KNNQueryBuilder class.

Though k-NN plugin has KNNQueryBuilder, as mentioned in the desc, the library is packaged as zip and not as a jar, which makes it unusable for typical Java projects.

Would you able to help me with the rationale on why was it packaged as a zip rather than a jar. Is packaging it as a jar a viable option?

[Xtansia]

@kannangce The zip packaging is just how OpenSearch plugins are packaged and distributed in general. You would need to ask on opensearch-project/k-NN
if there's a possibility for them to publish a jar