Davies Liu created SPARK-11111: ---------------------------------- Summary: Fast null-safe join Key: SPARK-11111 URL: https://issues.apache.org/jira/browse/SPARK-11111 Project: Spark Issue Type: Improvement Reporter: Davies Liu Assignee: Davies Liu
Today, null safe joins are executed with a Cartesian product. {code} scala> sqlContext.sql("select * from t a join t b on (a.i <=> b.i)").explain == Physical Plan == TungstenProject [i#2,j#3,i#7,j#8] Filter (i#2 <=> i#7) CartesianProduct LocalTableScan [i#2,j#3], [[1,1]] LocalTableScan [i#7,j#8], [[1,1]] {code} One option is to add this rewrite to the optimizer: {code} select * from t a join t b on coalesce(a.i, <default>) = coalesce(b.i, <default>) AND (a.i <=> b.i) {code} Acceptance criteria: joins with only null safe equality should not result in a Cartesian product. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org