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ASF GitHub Bot commented on DRILL-5546: --------------------------------------- Github user jinfengni commented on a diff in the pull request: https://github.com/apache/drill/pull/906#discussion_r136182353 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/ProjectPrel.java --- @@ -35,18 +35,43 @@ import org.apache.calcite.rex.RexNode; import org.apache.calcite.sql.SqlKind; +/** + * A physical Prel node for Project operator. + */ public class ProjectPrel extends DrillProjectRelBase implements Prel{ static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ProjectPrel.class); + private final boolean outputProj; public ProjectPrel(RelOptCluster cluster, RelTraitSet traits, RelNode child, List<RexNode> exps, RelDataType rowType) { + this(cluster, traits, child, exps, rowType, false); + } + + /** + * Constructor for ProjectPrel. + * @param cluster + * @param traits traits of ProjectPrel node + * @param child input + * @param exps list of RexNode, representing expressions of projection. + * @param rowType output rowType of projection expression. + * @param outputProj true if ProjectPrel is inserted by {@link org.apache.drill.exec.planner.physical.visitor.TopProjectVisitor} + * Such top Project operator does the following processing, before the result was presented to Screen/Writer + * 1) ensure final output field names are preserved, + * 2) handle cases where input does not return any batch (a fast NONE) (see ProjectRecordBatch.handleFastNone() method) + * 3) handle cases where expressions in upstream operator were evaluated to NULL type --- End diff -- Done. > Schema change problems caused by empty batch > -------------------------------------------- > > Key: DRILL-5546 > URL: https://issues.apache.org/jira/browse/DRILL-5546 > Project: Apache Drill > Issue Type: Bug > Reporter: Jinfeng Ni > Assignee: Jinfeng Ni > > There have been a few JIRAs opened related to schema change failure caused by > empty batch. This JIRA is opened as an umbrella for all those related JIRAS ( > such as DRILL-4686, DRILL-4734, DRILL4476, DRILL-4255, etc). > -- This message was sent by Atlassian JIRA (v6.4.14#64029)