@Nullable
          @Override
          protected TrinoRow computeNext() {
            if (nextPosition == positionCount) {
              return endOfData();
            }
            int position = nextPosition;
            nextPosition++;
            return new TrinoRow(types, page, position);
          }
Gets the position in the Block this row was originally created from.
amoro-format-mixed/amoro-mixed-trino/src/main/java/org/apache/amoro/trino/delete/TrinoRow.java