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ASF GitHub Bot commented on FLINK-5266: --------------------------------------- Github user fhueske commented on a diff in the pull request: https://github.com/apache/flink/pull/2961#discussion_r91738368 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/api/table/table.scala --- @@ -881,24 +883,21 @@ class GroupWindowedTable( * }}} */ def select(fields: Expression*): Table = { --- End diff -- At the moment there is no way to specify watermarks inside of a Table API or SQL query. This can only be done on a DataStream before it is converted into a Table. Therefore, watermarks and timestamps are already assigned before the first Table or SQL operator can remove anything. In case of a TableSource which assigns timestamps, the TableSource needs to take care that the assignment happens before a pushed-down projection is applied. > Eagerly project unused fields when selecting aggregation fields > --------------------------------------------------------------- > > Key: FLINK-5266 > URL: https://issues.apache.org/jira/browse/FLINK-5266 > Project: Flink > Issue Type: Improvement > Components: Table API & SQL > Reporter: Kurt Young > Assignee: Kurt Young > > When we call table's {{select}} method and if it contains some aggregations, > we will project fields after the aggregation. Would be better to project > unused fields before the aggregation, and can furthermore leave the > opportunity to push the project into scan. > For example, the current logical plan of a simple query: > {code} > table.select('a.sum as 's, 'a.max) > {code} > is > {code} > LogicalProject(s=[$0], TMP_2=[$1]) > LogicalAggregate(group=[{}], TMP_0=[SUM($5)], TMP_1=[MAX($5)]) > LogicalTableScan(table=[[supplier]]) > {code} > Would be better if we can project unused fields right after scan, and looks > like this: > {code} > LogicalProject(s=[$0], EXPR$1=[$0]) > LogicalAggregate(group=[{}], EXPR$1=[SUM($0)]) > LogicalProject(a=[$5]) > LogicalTableScan(table=[[supplier]]) > {code} -- This message was sent by Atlassian JIRA (v6.3.4#6332)