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Sort HadoopIndexer rows by time+dim bucket to help reduce spilling #1097

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Merged
fjy merged 1 commit into from
Feb 25, 2015
Merged

Sort HadoopIndexer rows by time+dim bucket to help reduce spilling #1097

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9 changes: 6 additions & 3 deletions indexing-hadoop/src/main/java/io/druid/indexer/HadoopDruidIndexerMapper.java
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Original file line number Diff line number Diff line change
Expand Up @@ -32,13 +32,15 @@ public abstract class HadoopDruidIndexerMapper<KEYOUT, VALUEOUT> extends Mapper<
{
private HadoopDruidIndexerConfig config;
private StringInputRowParser parser;
protected GranularitySpec granularitySpec;

@Override
protected void setup(Context context)
throws IOException, InterruptedException
{
config = HadoopDruidIndexerConfig.fromConfiguration(context.getConfiguration());
parser = config.getParser();
granularitySpec = config.getGranularitySpec();
}

public HadoopDruidIndexerConfig getConfig()
Expand Down Expand Up @@ -69,9 +71,10 @@ protected void map(
throw e;
}
}
GranularitySpec spec = config.getGranularitySpec();
if (!spec.bucketIntervals().isPresent() || spec.bucketInterval(new DateTime(inputRow.getTimestampFromEpoch()))
.isPresent()) {

if (!granularitySpec.bucketIntervals().isPresent()
|| granularitySpec.bucketInterval(new DateTime(inputRow.getTimestampFromEpoch()))
.isPresent()) {
innerMap(inputRow, value, context);
}
}
Expand Down
22 changes: 21 additions & 1 deletion indexing-hadoop/src/main/java/io/druid/indexer/IndexGeneratorJob.java
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,8 @@
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hashing;
import com.google.common.io.Closeables;
import com.google.common.primitives.Longs;
import com.metamx.common.IAE;
Expand All @@ -34,7 +36,9 @@
import com.metamx.common.logger.Logger;
import io.druid.collections.StupidPool;
import io.druid.data.input.InputRow;
import io.druid.data.input.Rows;
import io.druid.data.input.impl.StringInputRowParser;
import io.druid.granularity.QueryGranularity;
import io.druid.offheap.OffheapBufferPool;
import io.druid.query.aggregation.AggregatorFactory;
import io.druid.segment.IndexIO;
Expand Down Expand Up @@ -214,6 +218,8 @@ public boolean run()

public static class IndexGeneratorMapper extends HadoopDruidIndexerMapper<BytesWritable, Text>
{
private static final HashFunction hashFunction = Hashing.murmur3_128();

@Override
protected void innerMap(
InputRow inputRow,
Expand All @@ -228,10 +234,24 @@ protected void innerMap(
throw new ISE("WTF?! No bucket found for row: %s", inputRow);
}

final long truncatedTimestamp = granularitySpec.getQueryGranularity().truncate(inputRow.getTimestampFromEpoch());
final byte[] hashedDimensions = hashFunction.hashBytes(
HadoopDruidIndexerConfig.jsonMapper.writeValueAsBytes(
Rows.toGroupKey(
truncatedTimestamp,
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@cheddar cheddar Feb 12, 2015

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Probably doesn't matter, but I don't think the truncatedTimestamp is technically needed in the hashed dimensions set.

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@xvrl xvrl Feb 13, 2015

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Agree, I just left it out of precaution as part of the sort key, just in case something in the reducer inadvertently depended on input rows being sorted by time first.

inputRow
)
)
).asBytes();

context.write(
new SortableBytes(
bucket.get().toGroupKey(),
Longs.toByteArray(inputRow.getTimestampFromEpoch())
// sort rows by truncated timestamp and hashed dimensions to help reduce spilling on the reducer side
ByteBuffer.allocate(Longs.BYTES + hashedDimensions.length)
.putLong(truncatedTimestamp)
.put(hashedDimensions)
.array()
).toBytesWritable(),
text
);
Expand Down