[PIG-4410] Fix testRankWithEmptyReduce in tez mode

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.15.0
• Component/s: tez
• Hadoop Flags: Reviewed
• Assignee: Daniel Dai
• Reporter: Daniel Dai
• Created: 04/Feb/15 21:40
• Updated: 07/Jun/15 03:48
• Resolved: 04/Feb/15 22:15

Description

testRankWithEmptyReduce added in PIG-4392 failed in tez mode. The reason is POReservoirSample produce more sample than necessary. In particular, if the input of the vertex is empty, it produces a fake tuple which does not have the original data, but a marked field plus 0 rowNum. That cause the WeightedRangePartitioner fail:

Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer
	at org.apache.pig.backend.hadoop.HDataType.getWritableComparableTypes(HDataType.java:115)
	at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.partitioners.WeightedRangePartitioner.getPigNullableWritable(WeightedRangePartitioner.java:192)

Another issue I found is GetMemNumRows, I erroneously add the size of mark tuple, which make the size estimation inaccurate. I put the fix in the same patch.

Issue Links

• is related to: PIG-4392 RANK BY fails when default_parallel is greater than cardinality of field being ranked by