rdblue commented on a change in pull request #23266: [SPARK-26313][SQL] move read related methods from Table to read related mix-in traits URL: https://github.com/apache/spark/pull/23266#discussion_r240379327
########## File path: sql/core/src/main/java/org/apache/spark/sql/sources/v2/SupportsBatchRead.java ########## @@ -20,14 +20,27 @@ import org.apache.spark.annotation.Evolving; import org.apache.spark.sql.sources.v2.reader.Scan; import org.apache.spark.sql.sources.v2.reader.ScanBuilder; +import org.apache.spark.sql.types.StructType; /** - * An empty mix-in interface for {@link Table}, to indicate this table supports batch scan. - * <p> - * If a {@link Table} implements this interface, its {@link Table#newScanBuilder(DataSourceOptions)} - * must return a {@link ScanBuilder} that builds {@link Scan} with {@link Scan#toBatch()} - * implemented. - * </p> + * A mix-in interface for {@link Table} to provide data reading ability of batch processing. */ @Evolving -public interface SupportsBatchRead extends Table { } +public interface SupportsBatchRead extends Table { + + /** + * Returns the schema of this table. + */ + StructType schema(); + + /** + * Returns a {@link ScanBuilder} which can be used to build a {@link Scan} later. The built + * {@link Scan} must implement {@link Scan#toBatch()}. Spark will call this method for each data + * scanning query. Review comment: Spark will call this method to configure each scan. Using "scanning query" implies that it will be called just once per query, which isn't true if the table is scanned twice in a query. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org