/*
* 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.facebook.presto.operator;
import com.facebook.presto.block.Block;
import com.facebook.presto.block.BlockBuilder;
import com.facebook.presto.tuple.TupleInfo;
import io.airlift.slice.Slices;
import java.util.List;
import static com.facebook.presto.tuple.TupleInfo.SINGLE_BOOLEAN;
public class MarkDistinctHash
{
private final GroupByHash groupByHash;
private long nextDistinctId;
public MarkDistinctHash(List<TupleInfo.Type> types, int[] channels)
{
this(types, channels, 10_000);
}
public MarkDistinctHash(List<TupleInfo.Type> types, int[] channels, int expectedDistinctValues)
{
this.groupByHash = new GroupByHash(types, channels, expectedDistinctValues);
}
public long getEstimatedSize()
{
return groupByHash.getEstimatedSize();
}
public Block markDistinctRows(Page page)
{
int positionCount = page.getPositionCount();
int blockSize = SINGLE_BOOLEAN.getFixedSize() * positionCount;
BlockBuilder blockBuilder = new BlockBuilder(SINGLE_BOOLEAN, blockSize, Slices.allocate(blockSize).getOutput());
GroupByIdBlock ids = groupByHash.getGroupIds(page);
for (int i = 0; i < ids.getPositionCount(); i++) {
if (ids.getGroupId(i) == nextDistinctId) {
blockBuilder.append(true);
nextDistinctId++;
}
else {
blockBuilder.append(false);
}
}
return blockBuilder.build();
}
}