jiaan.geng created SPARK-32934: ---------------------------------- Summary: Support a new window frame could improve the performance for NTH_VALUE,FIRST_VALUE,LAST_VALUE Key: SPARK-32934 URL: https://issues.apache.org/jira/browse/SPARK-32934 Project: Spark Issue Type: Sub-task Components: SQL Affects Versions: 3.1.0 Reporter: jiaan.geng
Spark SQL support some window function like NTH_VALUE,FIRST_VALUE and LAST_VALUE If we specify window frame like {code:java} UNBOUNDED PRECEDING AND CURRENT ROW {code} or {code:java} UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING {code} We can elimate some calculations. For example: if we execute the SQL show below: {code:java} SELECT NTH_VALUE(col, 2) OVER(ORDER BY rank UNBOUNDED PRECEDING AND CURRENT ROW) FROM tab; {code} The output for row number greater than 1, return the fixed value. otherwise, return null. So we just calculate the value once and notice whether the row number less than 2. UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING is simpler. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org