Criteria are repeated in the query

[ddeboer]

When doing Lens.find() with a where: {...} filter argument, that filter appears twice in the query:

• once in the SELECT DISTINCT ?iri subquery, where it’s really needed for a proper selection of resources
• again in the main query, where it’s redundant and may only slow down query execution.

[karelklima]

This is by design, although I am not convinced the design is right. The reasoning behind the implementation is that if you have e.g. array-like properties and use filter on that, I would expect only the matching values be present in the final result.

[karelklima]

I am open to changing the approach in the next major version. I too have noticed the performance impact.

[ddeboer]

Yeah, as I understood it, the filters would only determine which resources are returned (?iri) from the query, not limiting the data per resource. Doing the latter can easily be done in userland.

[karelklima]

There are also other use cases like optional properties that are affected by this. What I can do is try to remove the "extra" filtering from the main query and see how many tests fail.