[HIVE-8613] percentile_approx raise a comparator error

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.12.0
• Fix Version/s: 1.1.0
• Assignee: Navis Ryu
• Reporter: Nicolas Lalevée
• Created: 27/Oct/14 17:33
• Updated: 12/Feb/15 23:41
• Resolved: 23/Dec/14 19:27

Description

I have implemented an UADF which wrap around percentile_approx, and I have been hit by the following stack trace:

Caused by: java.lang.IllegalArgumentException: Comparison method violates its general contract!
	at java.util.ComparableTimSort.mergeLo(ComparableTimSort.java:714)
	at java.util.ComparableTimSort.mergeAt(ComparableTimSort.java:451)
	at java.util.ComparableTimSort.mergeCollapse(ComparableTimSort.java:376)
	at java.util.ComparableTimSort.sort(ComparableTimSort.java:182)
	at java.util.ComparableTimSort.sort(ComparableTimSort.java:146)
	at java.util.Arrays.sort(Arrays.java:472)
	at java.util.Collections.sort(Collections.java:155)
	at org.apache.hadoop.hive.ql.udf.generic.NumericHistogram.merge(NumericHistogram.java:161)

In my use case, with my special UADF, there were Double.NaN

Implementing a proper double comparaison with Double.compare in com.goojet.mapred.hive.udf.NumericHistogram.Coord.compareTo(Object) fixes it.