RexToLixTranslator offers some public static methods to help you translate things to expressions (Ling4j). E.g. RexToLixTranslator.translateProjects might be what you need the most.
After you get expressions, a way I know to execute it is by utilizing Janino [1] to compile expressions to bytecode and execute the bytecode directly. The following are some code examples how Apache Beam is doing: 1. translate projects to expressions. [2] 2. compile expressions. [3] 3. execute the compiled code. [4] [1]: https://janino-compiler.github.io/janino/ [2]: https://github.com/apache/beam/blob/master/sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/rel/BeamCalcRel.java#L159 [3]: https://github.com/apache/beam/blob/7c80ecb8c354575e4332f0f1731f1b5a3f0c4362/sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/rel/BeamCalcRel.java#L232 [4]: https://github.com/apache/beam/blob/7c80ecb8c354575e4332f0f1731f1b5a3f0c4362/sdks/java/extensions/sql/src/main/java/org/apache/beam/sdk/extensions/sql/impl/rel/BeamCalcRel.java#L259 -Rui On Mon, May 18, 2020 at 7:43 AM Jon Pither <jon.pit...@gmail.com> wrote: > Hi, > > Is it possible for an adapter to leverage RexImpTable to handle > calculations? > > From RexImpTable I can get an Implementor for a given operation in a > RexCall, but then the implement method that would generate an expression, > takes a RexToLixTranslator. The RexToLixTranslator has a private > constructor, so I'm not sure how to get hold of one. I also couldn't find > any supporting prior art in the various adapters in the code-base. > > Does my approach make sense, to want to use Calcite for > handling calculations across projects, filters & join conditions? > > Context is that our database is a rule-engine that runs in-process - I want > to pass it arbitrary functions that could potentially wrap Linq > expressions, to implement a wider range of SQL backed by Calcite. > > Regards, > > Jon. >
