Hi Julian,
it seems to me that
org.apache.calcite.rel.type.RelDataTypeFactoryImpl.JavaType, which is a
subtype of RelDataType, would be the best place to model this. How about
I add an Accessor contract and a field to JavaType to take care of
producing expressions for the enumerable adapater? By default, this will
use an implementation based on public fields or record accessors
depending on class type. In addition, I would also add an implementation
that works based on calling getter methods, since that is what I need
for my purposes.
Wdyt?
Regards,
Christian
Am 31.05.2024 um 03:02 schrieb Julian Hyde:
Thanks for doing these experiments, Christian, and documenting what you found.
I think you’re running into the limitations of ReflectiveSchema. It works with
POJOs (java classes with public fields) but hasn’t been tested for richer
variations and therefore just doesn’t work. In many cases, it can be fixed
(seehttps://issues.apache.org/jira/browse/CALCITE-6244 for example).
I’m uneasy about extending RelDataType to return JavaRowFormat. That seems to
be introducing a physical property into a logical data type; also, it is
surfacing the details of one particular adapter (enumerable). Maybe there is a
way to surface this information via annotations or the java.sql.Wrapper
interface without extending RelDataType.
Julian
On May 24, 2024, at 11:33 AM, Christian Beikov<christian.bei...@gmail.com>
wrote:
Hello,
in my recent experiments I ran into some issues when trying to unnest an array
of struct.
The query is roughly this: select t.id, e.value1 from MyTable t,
unnest(t.structArray) e
EnumerableTableScan#fieldExpression will then try to generate code that converts the value of the
"structArray" column to a List<List>, which is where the problems start to arise. This
code does not seem to be tested at all, because currently generates a compile error, due to missing a
cast to "Iterable". It also assumes the data is already available in the JavaRowFormat.CUSTOM
representation, but AFAIU, it could be in any format.
When using RelRecordType for structs, regular struct columns seem to expect
JavaRowFormat.ARRAY, but struct arrays don't seem to behave the same way.
What is the expected data format that an enumerator should return for struct
arrays that are typed as RelRecordType?
To support formats per type it might be nice to allow specifying the
JavaRowFormat on RelDataType. Wdyt?
Also, is there a way to allow working with custom Java types for table/struct
rows? From looking at AbstractCursor#createAccessor, it seems the Aviatica code
currently only works with classes that expose public fields.
Regards,
Christian
