I'm trying to add the ability to push-down the evaluation of a
function to my storage engine (Solr in this case). For instance,
select movie_id, user_id, custom_rating('foo') as rating from movie_ratings
where custom_rating('foo') is some function in my storage engine.
This seems like a UDF in Calcite terms but I'm not having any luck
getting the function node passed to my adapter code.
I've tried adding a ScalarFunction to my schema but it gets evaluated
early (long before my adapter code gets hit).
I've also tried a TableFunction, but always end up with this error (using 1.11)
Caused by: org.apache.calcite.runtime.CalciteContextException: From
line 1, column 27 to line 1, column 36: No match found for function
signature custom_rating(<CHARACTER>)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at
org.apache.calcite.runtime.Resources$ExInstWithCause.ex(Resources.java:463)
at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:796)
at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:784)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.newValidationError(SqlValidatorImpl.java:4080)
at
org.apache.calcite.sql.validate.SqlValidatorImpl.handleUnresolvedFunction(SqlValidatorImpl.java:1614)
at org.apache.calcite.sql.SqlFunction.deriveType(SqlFunction.java:278)
at org.apache.calcite.sql.SqlFunction.deriveType(SqlFunction.java:223)
at
org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:4445)
at
org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:4432)
at org.apache.calcite.sql.SqlCall.accept(SqlCall.java:137)
which when debugging looks like the function isn't registered
correctly in the schema but I've overridden protected Multimap<String,
Function> getFunctionMultimap() in my schema impl. to include my
function.
I scanned the docs and the UDF code (e.g. Smalls) but don't see an
example of a adapter supplied function. Any guidance you can provide
is appreciated.
Thanks.
Tim
