Add support for adaptive partial aggregation #20979
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| Original file line number | Diff line number | Diff line change |
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| /* | ||
| * 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.aggregation.partial; | ||
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| import io.airlift.units.DataSize; | ||
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| import java.util.OptionalLong; | ||
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| import static java.util.Objects.requireNonNull; | ||
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| public class PartialAggregationController | ||
| { | ||
| /** | ||
| * Process enough pages to fill up the partial aggregation buffer, before considering disabling partial aggregation. | ||
| * With 16 MB as default partial agg buffer, this means we process at least 24 MB of input data before considering to disable partial agg. | ||
| * We use bytes instead of rows as the floor to disable partial aggregation due to issues with file skew when rows are small. We want to make sure | ||
| * the partial aggregation buffer is fully utilized before making the decision on disabling partial aggregation. | ||
| */ | ||
| private static final double DISABLE_AGGREGATION_BUFFER_SIZE_TO_INPUT_BYTES_RATIO = 1.5; | ||
|
Contributor
There was a problem hiding this comment. Should these values be paramaterizable ? |
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| /** | ||
| * Re-enable partial aggregation periodically, in case later data can be partially aggregated more effectively. | ||
| */ | ||
| private static final double ENABLE_AGGREGATION_BUFFER_SIZE_TO_INPUT_BYTES_RATIO = DISABLE_AGGREGATION_BUFFER_SIZE_TO_INPUT_BYTES_RATIO * 200; | ||
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| private final DataSize maxPartialAggregationMemorySize; | ||
| private final double uniqueRowsRatioThreshold; | ||
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| private volatile boolean partialAggregationDisabled; | ||
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Contributor
Author
There was a problem hiding this comment. to avoid synchronized on read path |
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| private long totalBytesProcessed; | ||
| private long totalRowsProcessed; | ||
| private long totalUniqueRowsProduced; | ||
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| public PartialAggregationController(DataSize maxPartialAggregationMemorySize, double uniqueRowsRatioThreshold) | ||
| { | ||
| this.maxPartialAggregationMemorySize = requireNonNull(maxPartialAggregationMemorySize, "maxPartialMemory is null"); | ||
| this.uniqueRowsRatioThreshold = uniqueRowsRatioThreshold; | ||
| } | ||
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| public boolean isPartialAggregationDisabled() | ||
| { | ||
| return partialAggregationDisabled; | ||
| } | ||
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| public synchronized void onFlush(long bytesProcessed, long rowsProcessed, OptionalLong uniqueRowsProduced) | ||
| { | ||
| if (!partialAggregationDisabled && !uniqueRowsProduced.isPresent()) { | ||
| // when partial aggregation has been re-enabled, ignore stats from disabled flushes | ||
| return; | ||
| } | ||
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| totalBytesProcessed += bytesProcessed; | ||
| totalRowsProcessed += rowsProcessed; | ||
| uniqueRowsProduced.ifPresent(value -> totalUniqueRowsProduced += value); | ||
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| if (!partialAggregationDisabled && shouldDisablePartialAggregation()) { | ||
| partialAggregationDisabled = true; | ||
| } | ||
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| if (partialAggregationDisabled && totalBytesProcessed >= maxPartialAggregationMemorySize.toBytes() * ENABLE_AGGREGATION_BUFFER_SIZE_TO_INPUT_BYTES_RATIO) { | ||
| totalBytesProcessed = 0; | ||
| totalRowsProcessed = 0; | ||
| totalUniqueRowsProduced = 0; | ||
| partialAggregationDisabled = false; | ||
| } | ||
| } | ||
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| private boolean shouldDisablePartialAggregation() | ||
| { | ||
| return totalBytesProcessed >= maxPartialAggregationMemorySize.toBytes() * DISABLE_AGGREGATION_BUFFER_SIZE_TO_INPUT_BYTES_RATIO | ||
| && ((double) totalUniqueRowsProduced / totalRowsProcessed) > uniqueRowsRatioThreshold; | ||
| } | ||
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| public PartialAggregationController duplicate() | ||
| { | ||
| return new PartialAggregationController(maxPartialAggregationMemorySize, uniqueRowsRatioThreshold); | ||
| } | ||
| } | ||
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are these configs same as the ones used in Trino ?
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Yes they are