SortedMergeBucketMapjoinProc.java example

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.hive.ql.optimizer;

import java.util.Stack;

import org.apache.hadoop.hive.conf.HiveConf;
import org.apache.hadoop.hive.ql.ErrorMsg;
import org.apache.hadoop.hive.ql.exec.MapJoinOperator;
import org.apache.hadoop.hive.ql.exec.SMBMapJoinOperator;
import org.apache.hadoop.hive.ql.lib.Node;
import org.apache.hadoop.hive.ql.lib.NodeProcessor;
import org.apache.hadoop.hive.ql.lib.NodeProcessorCtx;
import org.apache.hadoop.hive.ql.parse.ParseContext;
import org.apache.hadoop.hive.ql.parse.SemanticException;

public class SortedMergeBucketMapjoinProc extends AbstractSMBJoinProc implements NodeProcessor {
  public SortedMergeBucketMapjoinProc(ParseContext pctx) {
    super(pctx);
  }

  public SortedMergeBucketMapjoinProc() {
  }

  @Override
  public Object process(Node nd, Stack<Node> stack, NodeProcessorCtx procCtx,
      Object... nodeOutputs) throws SemanticException {
    if (nd instanceof SMBMapJoinOperator) {
      return null;
    }

    MapJoinOperator mapJoinOp = (MapJoinOperator) nd;
    SortBucketJoinProcCtx smbJoinContext = (SortBucketJoinProcCtx) procCtx;

    boolean convert =
        canConvertBucketMapJoinToSMBJoin(mapJoinOp, stack, smbJoinContext, nodeOutputs);

    // Throw an error if the user asked for sort merge bucketed mapjoin to be enforced
    // and sort merge bucketed mapjoin cannot be performed
    if (!convert &&
        pGraphContext.getConf().getBoolVar(
            HiveConf.ConfVars.HIVEENFORCESORTMERGEBUCKETMAPJOIN)) {
      throw new SemanticException(ErrorMsg.SORTMERGE_MAPJOIN_FAILED.getMsg());
    }

    if (convert) {
      convertBucketMapJoinToSMBJoin(mapJoinOp, smbJoinContext);
    }
    return null;
  }
}