Add an optimizer to add distinct below build side of semi join#25238
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feilong-liu merged 1 commit intoprestodb:masterfrom Jun 5, 2025
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Add an optimizer to add distinct below build side of semi join#25238feilong-liu merged 1 commit intoprestodb:masterfrom
feilong-liu merged 1 commit intoprestodb:masterfrom
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...rc/main/java/com/facebook/presto/sql/planner/iterative/rule/AddDistinctForSemiJoinBuild.java
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| private boolean nativeExecutionTypeRewriteEnabled; | ||
| private String expressionOptimizerName = DEFAULT_EXPRESSION_OPTIMIZER_NAME; | ||
| private boolean addExchangeBelowPartialAggregationOverGroupId; | ||
| private boolean addDistinctBelowSemiJoinBuild; |
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I'd like to run it for some time before turning it on as default.
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| import static com.facebook.presto.spi.plan.AggregationNode.isDistinct; | ||
| import static com.facebook.presto.spi.plan.AggregationNode.singleGroupingSet; | ||
| import static com.facebook.presto.sql.planner.plan.Patterns.semiJoin; | ||
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Please add small comment explaining the rule
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Description
We found that adding a distinct aggregation before a semi join on the build side can improve latency. This is probably due to the restriction that the build side of semi join is executed with single thread
presto/presto-main-base/src/main/java/com/facebook/presto/sql/planner/LocalExecutionPlanner.java
Line 2623 in a12b523
This PR works by adding a distinct aggregation below the semi join on the build side.
Motivation and Context
To improve latency of semi join
Impact
To improve latency of semi join
Test Plan
Unit tests
Contributor checklist
Release Notes
Please follow release notes guidelines and fill in the release notes below.