Github user jinfengni commented on a diff in the pull request: https://github.com/apache/drill/pull/906#discussion_r136185479 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/record/AbstractSingleRecordBatch.java --- @@ -125,4 +131,19 @@ public BatchSchema getSchema() { protected abstract boolean setupNewSchema() throws SchemaChangeException; protected abstract IterOutcome doWork(); + + /** + * Default behavior to handle fast NONE (incoming's first next() return NONE, in stead of OK_NEW_SCHEMA): + * FAST NONE could happen when the underneath Scan operators do not produce any batch with schema. + * + * This behavior could be override in each individual operator, if the operator's semantics is to + * inject a batch with schema. + * + * @return IterOutcome.NONE. + */ + protected IterOutcome handleFastNone() { + container.buildSchema(SelectionVectorMode.NONE); + return IterOutcome.NONE; + }; --- End diff -- done.
--- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. ---