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Apache Spark commented on SPARK-26205: -------------------------------------- User 'aokolnychyi' has created a pull request for this issue: https://github.com/apache/spark/pull/23171 > Optimize In expression for bytes, shorts, ints > ---------------------------------------------- > > Key: SPARK-26205 > URL: https://issues.apache.org/jira/browse/SPARK-26205 > Project: Spark > Issue Type: Improvement > Components: SQL > Affects Versions: 3.0.0 > Reporter: Anton Okolnychyi > Priority: Major > > Currently, {{In}} expressions are compiled into a sequence of if-else > statements, which results in O\(n\) time complexity. {{InSet}} is an > optimized version of {{In}}, which is supposed to improve the performance if > the number of elements is big enough. However, {{InSet}} actually degrades > the performance in many cases due to various reasons (benchmarks will be > available in SPARK-26203 and solutions are discussed in SPARK-26204). > The main idea of this JIRA is to make use of {{tableswitch}} and > {{lookupswitch}} bytecode instructions. In short, we can improve our time > complexity from O\(n\) to O\(1\) or at least O\(log n\) by using Java > {{switch}} statements. We will have O\(1\) time complexity if our case values > are compact and {{tableswitch}} can be used. Otherwise, {{lookupswitch}} will > give us O\(log n\). > An important benefit of the proposed approach is that we do not have to pay > an extra cost for autoboxing as in case of {{InSet}}. As a consequence, we > can substantially outperform {{InSet}} even on 250+ elements. > See > [here|https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-3.html#jvms-3.10] > and > [here|https://stackoverflow.com/questions/10287700/difference-between-jvms-lookupswitch-and-tableswitch] > for more information. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org