[FLINK-5266] Eagerly project unused fields when selecting aggregation fields

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.2.0
• Component/s: Table SQL / API
• Assignee: Kurt Young
• Reporter: Kurt Young
• Created: 06/Dec/16 01:39
• Updated: 15/Dec/16 11:55
• Resolved: 15/Dec/16 11:55

Description

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:

table.select('a.sum as 's, 'a.max)

is

LogicalProject(s=[$0], TMP_2=[$1])
  LogicalAggregate(group=[{}], TMP_0=[SUM($5)], TMP_1=[MAX($5)])
    LogicalTableScan(table=[[supplier]])

Would be better if we can project unused fields right after scan, and looks like this:

LogicalProject(s=[$0], EXPR$1=[$0])
  LogicalAggregate(group=[{}], EXPR$1=[SUM($0)])
    LogicalProject(a=[$5])
      LogicalTableScan(table=[[supplier]])

Issue Links

• links to: GitHub Pull Request #2961