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Hequn Cheng edited comment on FLINK-9422 at 5/24/18 1:54 AM: ------------------------------------------------------------- Hi, I agree that we need a dedicated operator. But I think adding a dedicated {{DISTINCT}} operator is better, and the {{DISTINCT}} operator would solve both the union problem and the distinct problem. The dedicated {{DISTINCT}} operator will only output append stream. was (Author: hequn8128): Hi, I agree that we need a dedicated operator. But I think adding a dedicated {{DISTINCT}} operator is better, and the {{DISTINCT}} operator would solve both the union problem and the distinct problem. > Dedicated operator for UNION on streaming tables with time attributes > --------------------------------------------------------------------- > > Key: FLINK-9422 > URL: https://issues.apache.org/jira/browse/FLINK-9422 > Project: Flink > Issue Type: Improvement > Components: Table API & SQL > Reporter: Fabian Hueske > Assignee: Ruidong Li > Priority: Minor > > We can implement a dedicated operator for a {{UNION}} operator on tables with > time attributes. Currently, {{UNION}} is translated into a {{UNION ALL}} and > a subsequent {{GROUP BY}} on all attributes without aggregation functions. > The state of the grouping operator is only clean up using state retention > timers. > The dedicated operator would leverage the monotonicity property of the time > attribute and watermarks to automatically clean up its state. -- This message was sent by Atlassian JIRA (v7.6.3#76005)