Pig and Hive source codes overview. Small hint: use "explain" to find the operation keywords, and search them in the source codes to find the corresponding class.

gistfile1.txt

Pig:
org.apache.pig.newplan.logical.relational.LogicalPlan
org.apache.pig.backend.hadoop.executionengine.physicalLayer.plans.PhysicalPlan
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.plans.MROperPlan
org.apache.pig.parser.QueryParserDriver.parse(String)
org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.compile(LogicalPlan,Properties)
org.apache.pig.PigServer.launchPlan(PhysicalPlan,String)
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher.compile(PhysicalPlan,PigContext)
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler.getJob(MROperPlan,MapReduceOper,Configuration,PigContext)
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler.compile(MROperPlan,String)
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher.launchPig(PhysicalPlan,String,PigContext)
org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POLocalRearrange.constructLROutput(List<Result>,List<Result>,Tuple)
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigGenericMapReduce.Map.collect(Context,Tuple)
org.apache.pig.impl.io.PigNullableWritable
org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POJoinPackage.getNext(Tuple)
org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POFRJoin

Hive:
org.apache.hadoop.hive.cli.CliDriver
org.apache.hadoop.hive.ql.Driver
org.apache.hadoop.hive.ql.Driver.run(String)
org.apache.hadoop.hive.ql.parse.ParseDriver.parse(String,Context)
org.apache.hadoop.hive.ql.parse.HiveLexer
org.apache.hadoop.hive.ql.parse.HiveParser
ql/src/java/org/apache/hadoop/hive/ql/parse/Hive.g
org.apache.hadoop.hive.ql.parse.ASTNode
org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer
org.apache.hadoop.hive.ql.QueryPlan
org.apache.hadoop.hive.ql.Driver.compile(String,boolean)
org.apache.hadoop.hive.ql.exec.Task<TextendsSerializable>
org.apache.hadoop.hive.ql.exec.CopyTask
org.apache.hadoop.hive.ql.exec.MoveTask
org.apache.hadoop.hive.ql.exec.TaskRunner
org.apache.hadoop.hive.ql.Driver.execute()
org.apache.hadoop.hive.ql.exec.ExecDriver
org.apache.hadoop.hive.ql.exec.ExecMapper
org.apache.hadoop.hive.ql.exec.ExecReducer
org.apache.hadoop.hive.ql.plan.MapredWork
org.apache.hadoop.hive.ql.exec.MapOperator
org.apache.hadoop.hive.ql.plan.MapredWork.getReducer()
org.apache.hadoop.hive.ql.exec.Operator<TextendsOperatorDesc>
org.apache.hadoop.hive.ql.exec.ReduceSinkOperator
org.apache.hadoop.hive.ql.exec.FileSinkOperator
org.apache.hadoop.hive.ql.exec.CommonJoinOperator<TextendsJoinDesc>
org.apache.hadoop.hive.ql.exec.JoinOperator