SelectionFetcher.java example

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/**
 * Copyright (C) 2014-2016 LinkedIn Corp. (pinot-core@linkedin.com)
 *
 * 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.linkedin.pinot.core.query.selection;

import com.linkedin.pinot.common.data.FieldSpec;
import com.linkedin.pinot.common.utils.DataSchema;
import com.linkedin.pinot.core.common.Block;
import com.linkedin.pinot.core.query.selection.iterator.DoubleArraySelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.DoubleSelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.FloatArraySelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.FloatSelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.IntArraySelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.IntSelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.LongArraySelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.LongSelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.SelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.SelectionSingleValueColumnWithDictIterator;
import com.linkedin.pinot.core.query.selection.iterator.StringArraySelectionColumnIterator;
import com.linkedin.pinot.core.query.selection.iterator.StringSelectionColumnIterator;
import java.io.Serializable;


/**
 * Selection fetcher is used for querying rows from given blocks and schema.
 * SelectionFetcher will initialize iterators on each data column and provide
 * the ability to return a Serializable array as a row for a given docId.
 *
 */
public class SelectionFetcher {
  private final int _numColumns;
  private final SelectionColumnIterator[] _selectionColumnIterators;

  public SelectionFetcher(Block[] blocks, DataSchema dataSchema) {
    _numColumns = blocks.length;
    _selectionColumnIterators = new SelectionColumnIterator[_numColumns];

    for (int i = 0; i < _numColumns; i++) {
      Block block = blocks[i];
      FieldSpec.DataType columnType = dataSchema.getColumnType(i);
      if (block.getMetadata().hasDictionary()) {
        // With dictionary

        switch (columnType) {
          // Single value
          case INT:
          case LONG:
          case FLOAT:
          case DOUBLE:
          case STRING:
            _selectionColumnIterators[i] = new SelectionSingleValueColumnWithDictIterator(block);
            break;
          // Multi value
          case INT_ARRAY:
            _selectionColumnIterators[i] = new IntArraySelectionColumnIterator(block);
            break;
          case FLOAT_ARRAY:
            _selectionColumnIterators[i] = new FloatArraySelectionColumnIterator(block);
            break;
          case LONG_ARRAY:
            _selectionColumnIterators[i] = new LongArraySelectionColumnIterator(block);
            break;
          case DOUBLE_ARRAY:
            _selectionColumnIterators[i] = new DoubleArraySelectionColumnIterator(block);
            break;
          case STRING_ARRAY:
            _selectionColumnIterators[i] = new StringArraySelectionColumnIterator(block);
            break;
          default:
            throw new UnsupportedOperationException();
        }
      } else {
        // No dictionary

        switch (columnType) {
          case INT:
            _selectionColumnIterators[i] = new IntSelectionColumnIterator(block);
            break;
          case LONG:
            _selectionColumnIterators[i] = new LongSelectionColumnIterator(block);
            break;
          case FLOAT:
            _selectionColumnIterators[i] = new FloatSelectionColumnIterator(block);
            break;
          case DOUBLE:
            _selectionColumnIterators[i] = new DoubleSelectionColumnIterator(block);
            break;
          case STRING:
            _selectionColumnIterators[i] = new StringSelectionColumnIterator(block);
            break;
          // TODO: add multi value support
          default:
            throw new UnsupportedOperationException();
        }
      }
    }
  }

  public Serializable[] getRow(int docId) {
    final Serializable[] row = new Serializable[_numColumns];
    for (int i = 0; i < _numColumns; i++) {
      row[i] = _selectionColumnIterators[i].getValue(docId);
    }
    return row;
  }
}