masayuki038

  @Override
  public RelNode toRel(RelOptTable.ToRelContext context, RelOptTable relOptTable) {
    int fieldCount = relOptTable.getRowType().getFieldCount();
    Integer[] fields = AvroEnumerator.identityList(fieldCount);
    return new AvroTableScan(context.getCluster(), relOptTable, fields);
  }

masayuki038

  public Enumerable<Object> project(DataContext root, Integer[] fields) {
    return new AbstractEnumerable<Object>() {
      public Enumerator<Object> enumerator() {
        return new AvroEnumerator(records, fields);
      }
    };
  }

masayuki038

public class AvroEnumerator implements Enumerator<Object> {

  private List<GenericData.Record> records;
  private Integer[] fields;
  private int pos;

  public AvroEnumerator(List<GenericData.Record> records, Integer[] fields) {
    this.records = records;
    this.fields = fields;
    this.pos = -1;

masayuki038

public class AvroTableScan extends TableScan implements EnumerableRel {
  private Integer[] fields;

masayuki038

  @Override
  public RelDataType deriveRowType() {
    List<RelDataTypeField> fieldList = getTable().getRowType().getFieldList();
    RelDataTypeFactory.Builder builder = getCluster().getTypeFactory().builder();
    Arrays.stream(fields).forEach(field -> builder.add(fieldList.get(field)));
    return builder.build();
  }

masayuki038

  @Override
  public void register(RelOptPlanner planner) {
    planner.addRule(AvroProjectTableScanRule.INSTANCE);
  }

masayuki038

  @Override
  public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
    PhysType physType = PhysTypeImpl.of(implementor.getTypeFactory(), getRowType(), pref.preferArray());
    return implementor.result(physType, Blocks.toBlock(
      Expressions.call(
        this.table.getExpression(AvroTable.class),
        "project",
        implementor.getRootExpression(),
        Expressions.constant(this.fields)
      )

masayuki038

public class AvroProjectTableScanRule extends RelOptRule {

  static final AvroProjectTableScanRule INSTANCE = new AvroProjectTableScanRule();

  public AvroProjectTableScanRule() {
    super(RelOptRule.operand(
      LogicalProject.class,
      RelOptRule.operand(AvroTableScan.class, RelOptRule.none())
    ), "AvroProjectTableScanRule");
  }

masayuki038

  @Override
  public void onMatch(RelOptRuleCall call) {
    LogicalProject project = call.rel(0);
    AvroTableScan scan = call.rel(1);
    Integer[] fields = getProjectFields(project.getProjects());

    call.transformTo(
      new AvroTableScan(scan.getCluster(), scan.getTable(), fields)
    );
  }

masayuki038

public class JdbcTest {

  private final static String CONNECTION_URL = "jdbc:calcite:model=target/test-classes/model.json";

  @BeforeClass
  public static void setUpOnce() throws ClassNotFoundException {
    Class.forName("org.apache.calcite.jdbc.Driver");
  }

  @Test