Yes, the examples you show will fail because the "let" expression reads streams into an in-memory List. All the Streaming Expressions expect a TupleStream to be passed in rather that a List.
There is an undocumented function that turns a List of tuples back into a Stream. The function is called "stream". Here is the syntax: let( a=search(techproducts, q="cat:electronics", fl="id, manu, price", sort="id asc"), b=search(techproducts, q="cat:electronics", fl="id, popularity, _version_", sort="id asc"), c=innerJoin(stream(a),stream(b), on=id) ) Joel Bernstein http://joelsolr.blogspot.com/ On Fri, Aug 16, 2019 at 4:30 AM Viktors Belovs <viktors.bel...@biologis.com> wrote: > Dear Solr Comunity, > > Recently I've been working with the 'let()' expression. > And I got in a sort of trouble, when I was trying combining it with the > different streaming expressions, > as well as trying to re-assign variables. > > As an example: > let( > a=search(techproducts, q="cat:electronics", fl="id, manu, price", > sort="id asc"), > b=search(techproducts, q="cat:electronics", fl="id, popularity, > _version_", sort="id asc"), > c=innerJoin(a, b, on=id) > ) > > In case with re-assigning the variables: > let( > a=search(techproducts, q="cat:electronics", fl="id, manu, price", > sort="id asc"), > b=a, > c=innerJoin(a, b, on=id) > ) > > According to documentation (Solr v8.1 the version I use) its possible to > store any kind values with 'let()' > function but it seems the usage of such a function is strictly limited for > specific mathematical operations. > > I was wondering if there is possible way to reduce the verbosity and > (potentially) > increase the efficiency of the streaming expression's performance, while > dealing and constructing complex > combinations of different streaming expressions. > > I assume the 'let()' doesn't suited for such purposes, but perhaps there > is an alternative way to do such a thing. > > Regards, > Viktors
