[SPARK-1914] Simplify CountFunction not to traverse to evaluate all child expressions.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.1, 1.1.0
• Component/s: SQL
• Assignee: Takuya Ueshin
• Reporter: Takuya Ueshin
• Created: 23/May/14 10:27
• Updated: 27/May/14 22:01
• Resolved: 26/May/14 07:17

Description

CountFunction should count up only if the child's evaluated value is not null.

Because it traverses to evaluate all child expressions, even if the child is null, it counts up if one of the all children is not null.

To reproduce this bug in sbt hive/console:

scala> hql("SELECT COUNT(*) FROM src1").collect()
res1: Array[org.apache.spark.sql.Row] = Array([25])

scala> hql("SELECT COUNT(*) FROM src1 WHERE key IS NULL").collect()
res2: Array[org.apache.spark.sql.Row] = Array([10])

scala> hql("SELECT COUNT(key + 1) FROM src1").collect()
res3: Array[org.apache.spark.sql.Row] = Array([25])

res3 should be 15 since there are 10 null keys.