Yash Datta created SPARK-6006: --------------------------------- Summary: Optimize count distinct in case high cardinality columns Key: SPARK-6006 URL: https://issues.apache.org/jira/browse/SPARK-6006 Project: Spark Issue Type: Improvement Components: SQL Affects Versions: 1.2.1, 1.1.1 Reporter: Yash Datta Priority: Minor Fix For: 1.3.0
In case there are a lot of distinct values, count distinct becomes too slow since it tries to hash partial results to one map. It can be improved by creating buckets/partial maps in an intermediate stage where same key from multiple partial maps of first stage hash to the same bucket. Later we can sum the size of these buckets to get total distinct count. -- 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