[FLINK-20794] Support to select distinct columns in the Table API

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Fix Version/s: 1.13.0
• Component/s: Table SQL / API
• Assignee: Unassigned
• Reporter: Dian Fu
• Created: 29/Dec/20 02:53
• Updated: 29/Dec/20 02:53

Description

Currently, there is no corresponding functionality in Table API for the following SQL:

SELECT DISTINCT users FROM Orders

For example, for the following job:

table.select("distinct a")

It will thrown the following exception:

org.apache.flink.table.api.ExpressionParserException: Could not parse expression at column 10: ',' expected but 'a' foundorg.apache.flink.table.api.ExpressionParserException: Could not parse expression at column 10: ',' expected but 'a' founddistinct a         ^
 at org.apache.flink.table.expressions.PlannerExpressionParserImpl$.throwError(PlannerExpressionParserImpl.scala:726) at org.apache.flink.table.expressions.PlannerExpressionParserImpl$.parseExpressionList(PlannerExpressionParserImpl.scala:710) at org.apache.flink.table.expressions.PlannerExpressionParserImpl.parseExpressionList(PlannerExpressionParserImpl.scala:47) at org.apache.flink.table.expressions.ExpressionParser.parseExpressionList(ExpressionParser.java:40) at org.apache.flink.table.api.internal.TableImpl.select(TableImpl.java:121)