HBaseColumn.java

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// Copyright 2012 Cloudera Inc.
//
// Licensed 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 com.cloudera.impala.catalog;

import com.cloudera.impala.thrift.TColumn;

// Describes an HBase column mapped to a Hive column (as described in the metastore).
// this.name describes the column name in Hive.
// This class adds the HBase columnFamily and columnQualifier,
// so we can read the column from HBase directly.
public class HBaseColumn extends Column implements Comparable<HBaseColumn> {
  private final String columnFamily_;
  private final String columnQualifier_;
  private final boolean binaryEncoded_;

  public HBaseColumn(String name, String columnFamily, String columnQualifier,
      boolean binaryEncoded, Type type, String comment, int position) {
    super(name, type, comment, position);
    columnFamily_ = columnFamily;
    columnQualifier_ = columnQualifier;
    binaryEncoded_ = binaryEncoded;
  }

  public String getColumnFamily() { return columnFamily_; }
  public String getColumnQualifier() { return columnQualifier_; }
  public boolean isBinaryEncoded() { return binaryEncoded_; }

  @Override
  // We order the HBase columns in the matadata based on columnFamily,columnQualifier,
  // to more easily map slots from HBase's Result.raw() to target slots in the backend.
  public int compareTo(HBaseColumn o) {
    int familyCmp = columnFamily_.compareTo(o.columnFamily_);
    if (familyCmp != 0) {
      return familyCmp;
    }
    int qualifierCmp = columnQualifier_.compareTo(o.columnQualifier_);
    return qualifierCmp;
  }

  @Override
  public TColumn toThrift() {
    TColumn colDesc = new TColumn(name_, type_.toThrift());
    if (comment_ != null) colDesc.setComment(comment_);
    colDesc.setCol_stats(getStats().toThrift());
    colDesc.setPosition(position_);
    colDesc.setIs_hbase_column(true);
    colDesc.setColumn_family(columnFamily_);
    colDesc.setColumn_qualifier(columnQualifier_);
    colDesc.setIs_binary(binaryEncoded_);
    return colDesc;
  }
}