[Enhancement] prefer two-phase plan for distinct aggregation in single node env #60029
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Signed-off-by: Murphy <mofei@starrocks.com>
| if (isSingleNodeExecution(ConnectContext.get())) { | ||
| return true; | ||
| } | ||
|
|
||
| return CollectionUtils.isNotEmpty(operator.getGroupingKeys()) | ||
| && aggMode == AUTO.ordinal() | ||
| 8000 && isTwoStageMoreEfficient(input, distinctColumns); |
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The most risky bug in this code is:
The ConnectContext.get() method call assumes that a valid context instance will always be returned, which might not be the case. If it returns null, this would lead to a NullPointerException.
You can modify the code like this:
+ ConnectContext context = ConnectContext.get();
+ if (context != null && isSingleNodeExecution(context)) {
+ return true;
+ }
|
[Java-Extensions Incremental Coverage Report]✅ pass : 0 / 0 (0%) |
[BE Incremental Coverage Report]✅ pass : 0 / 0 (0%) |
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Why I'm doing:
For this kind of query:
Different query plans and performance in a single-node env:
The 2-phase plan is clearly the better option; however, it is not the default. The default plan is the 3-phase plan, as it is more suitable for multi-node clusters due to its ability to handle data skew and provide better scalability. However, in a single-node cluster, the multi-phase plan offers no advantages and only adds unnecessary overhead.
Therefore, we aim to select the 2-phase plan for single-node environments.
What I'm doing:
Fixes #issue
What type of PR is this:
Does this PR entail a change in behavior?
If yes, please specify the type of change:
Checklist:
Bugfix cherry-pick branch check: