org.apache.hadoop.hive.ql.optimizer.GenMRRedSink1 Maven / Gradle / Ivy
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package org.apache.hadoop.hive.ql.optimizer;
import java.util.Map;
import java.util.Stack;
import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.exec.ReduceSinkOperator;
import org.apache.hadoop.hive.ql.exec.Task;
import org.apache.hadoop.hive.ql.lib.Node;
import org.apache.hadoop.hive.ql.lib.SemanticNodeProcessor;
import org.apache.hadoop.hive.ql.lib.NodeProcessorCtx;
import org.apache.hadoop.hive.ql.optimizer.GenMRProcContext.GenMapRedCtx;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.ql.plan.MapredWork;
import org.apache.hadoop.hive.ql.plan.OperatorDesc;
/**
* Processor for the rule - table scan followed by reduce sink.
*/
public class GenMRRedSink1 implements SemanticNodeProcessor {
public GenMRRedSink1() {
}
/**
* Reduce Sink encountered.
* a) If we are seeing this RS for first time, we initialize plan corresponding to this RS.
* b) If we are seeing this RS for second or later time then either query had a join in which
* case we will merge this plan with earlier plan involving this RS or plan for this RS
* needs to be split in two branches.
*
* @param nd
* the reduce sink operator encountered
* @param opProcCtx
* context
*/
public Object process(Node nd, Stack stack, NodeProcessorCtx opProcCtx,
Object... nodeOutputs) throws SemanticException {
ReduceSinkOperator op = (ReduceSinkOperator) nd;
GenMRProcContext ctx = (GenMRProcContext) opProcCtx;
Map, GenMapRedCtx> mapCurrCtx = ctx
.getMapCurrCtx();
GenMapRedCtx mapredCtx = mapCurrCtx.get(stack.get(stack.size() - 2));
Task currTask = mapredCtx.getCurrTask();
MapredWork currPlan = (MapredWork) currTask.getWork();
String currAliasId = mapredCtx.getCurrAliasId();
if (op.getNumChild() != 1) {
throw new IllegalStateException("Expecting operator " + op + " to have one child. " +
"But found multiple children : " + op.getChildOperators());
}
Operator reducer = op.getChildOperators().get(0);
Task oldTask = ctx.getOpTaskMap().get(reducer);
ctx.setCurrAliasId(currAliasId);
ctx.setCurrTask(currTask);
// If the plan for this reducer does not exist, initialize the plan
if (oldTask == null) {
if (currPlan.getReduceWork() == null) {
GenMapRedUtils.initPlan(op, ctx);
} else {
GenMapRedUtils.splitPlan(op, ctx);
}
} else {
// This will happen in case of joins. The current plan can be thrown away
// after being merged with the original plan
GenMapRedUtils.joinPlan(currTask, oldTask, ctx);
currTask = oldTask;
ctx.setCurrTask(currTask);
}
mapCurrCtx.put(op, new GenMapRedCtx(ctx.getCurrTask(), ctx.getCurrAliasId()));
if (GenMapRedUtils.hasBranchFinished(nodeOutputs)) {
ctx.addRootIfPossible(currTask);
return false;
}
return true;
}
}