cryptoe commented on code in PR #15470:
URL: https://github.com/apache/druid/pull/15470#discussion_r1542283346
##########
extensions-core/multi-stage-query/src/main/java/org/apache/druid/msq/querykit/groupby/GroupByQueryKit.java:
##########
@@ -164,39 +168,96 @@ public QueryDefinition makeQueryDefinition(
partitionBoost
);
- queryDefBuilder.add(
- StageDefinition.builder(firstStageNumber + 1)
- .inputs(new StageInputSpec(firstStageNumber))
- .signature(resultSignature)
- .maxWorkerCount(maxWorkerCount)
- .shuffleSpec(
- shuffleSpecFactoryPostAggregation != null
- ?
shuffleSpecFactoryPostAggregation.build(resultClusterBy, false)
- : null
- )
- .processorFactory(new
GroupByPostShuffleFrameProcessorFactory(queryToRun))
- );
+ final ShuffleSpec nextShuffleWindowSpec =
getShuffleSpecForNextWindow(originalQuery, maxWorkerCount);
- if (doLimitOrOffset) {
- final DefaultLimitSpec limitSpec = (DefaultLimitSpec)
queryToRun.getLimitSpec();
+ if (nextShuffleWindowSpec == null) {
queryDefBuilder.add(
- StageDefinition.builder(firstStageNumber + 2)
- .inputs(new StageInputSpec(firstStageNumber + 1))
+ StageDefinition.builder(firstStageNumber + 1)
+ .inputs(new StageInputSpec(firstStageNumber))
.signature(resultSignature)
- .maxWorkerCount(1)
- .shuffleSpec(null) // no shuffling should be required
after a limit processor.
- .processorFactory(
- new OffsetLimitFrameProcessorFactory(
- limitSpec.getOffset(),
- limitSpec.isLimited() ? (long)
limitSpec.getLimit() : null
- )
+ .maxWorkerCount(maxWorkerCount)
+ .shuffleSpec(
+ shuffleSpecFactoryPostAggregation != null
+ ?
shuffleSpecFactoryPostAggregation.build(resultClusterBy, false)
+ : null
)
+ .processorFactory(new
GroupByPostShuffleFrameProcessorFactory(queryToRun))
+ );
+
+ if (doLimitOrOffset) {
+ final DefaultLimitSpec limitSpec = (DefaultLimitSpec)
queryToRun.getLimitSpec();
+ queryDefBuilder.add(
+ StageDefinition.builder(firstStageNumber + 2)
+ .inputs(new StageInputSpec(firstStageNumber + 1))
+ .signature(resultSignature)
+ .maxWorkerCount(1)
+ .shuffleSpec(null) // no shuffling should be
required after a limit processor.
+ .processorFactory(
+ new OffsetLimitFrameProcessorFactory(
+ limitSpec.getOffset(),
+ limitSpec.isLimited() ? (long)
limitSpec.getLimit() : null
+ )
+ )
+ );
+ }
+ } else {
+ final RowSignature stageSignature;
+ // sort the signature to make sure the prefix is aligned
+ stageSignature = QueryKitUtils.sortableSignature(
+ resultSignature,
+ nextShuffleWindowSpec.clusterBy().getColumns()
+ );
+
+ queryDefBuilder.add(
+ StageDefinition.builder(firstStageNumber + 1)
+ .inputs(new StageInputSpec(firstStageNumber))
+ .signature(stageSignature)
+ .maxWorkerCount(maxWorkerCount)
+ .shuffleSpec(nextShuffleWindowSpec)
Review Comment:
I think the limit and offset should be applied on the grouping key. So it
should be ```
shuffleSpecFactoryPostAggregation != null
?
: null
```
The limit stage can then further partition the data
according to the next windowShuffleSpec no ?
Also we can actually short circuit it to a single
partition since limit always gets applied on 1 worker and 1 parition :)
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