我在试着理解Pig的 explain -功能（链接）。
假设以下示例：

A = load 'numbers' using PigStorage(',') as (name, age);
explain A;

这给了我：

# -----------------------------------------------

# New Logical Plan:

# -----------------------------------------------

A: (Name: LOStore Schema: name#5:bytearray,age#6:bytearray)
|
|---A: (Name: LOLoad Schema: name#5:bytearray,age#6:bytearray)RequiredFields:[0, 1]

# -----------------------------------------------

# Physical Plan:

# -----------------------------------------------

A: Store(fakefile:org.apache.pig.builtin.PigStorage) - scope-1
|
|---A: Load(file:///...pig-0.14.0/numbers:PigStorage(',')) - scope-0

2014-12-07 15:07:10,596 [main] INFO  org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRCompiler - File concatenation threshold: 100 optimistic? false
2014-12-07 15:07:10,609 [main] INFO  org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer - MR plan size before optimization: 1
2014-12-07 15:07:10,610 [main] INFO  org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer - MR plan size after optimization: 1

# --------------------------------------------------

# Map Reduce Plan

# --------------------------------------------------

MapReduce node scope-2
Map Plan
A: Store(fakefile:org.apache.pig.builtin.PigStorage) - scope-1
|
|---A: Load(file:///.../pig-0.14.0/numbers:PigStorage(',')) - scope-0--------
Global sort: false
----------------

我能看到什么？我发现输出结果相当混乱。