Github user vrozov commented on a diff in the pull request:
https://github.com/apache/drill/pull/926#discussion_r137658224
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/RecordReader.java ---
@@ -26,6 +26,9 @@
import org.apache.drill.exec.record.MaterializedField;
import org.apache.drill.exec.vector.ValueVector;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+@JsonTypeInfo(use=JsonTypeInfo.Id.NAME,
include=JsonTypeInfo.As.WRAPPER_OBJECT, property="type")
--- End diff --
AFAIK, it will not impact implementations of the `RecordReader` interface.
The annotation affects Jackson type inference when a physical operator has a
reference to a `RecordReader` and Jackson needs to construct a concrete
implementation of the `RecordReader`. Such information needs to be passed in
any case and the annotation specifies JSON syntax used to pass the type
information. To avoid the concern I'll move the annotation to the field
declaration in `DirectSubScan`. The effect of such move is that it will be
necessary to annotate `RecordReader` in every operator that may be passed as
part of a fragment to a remote node for execution.
---
