BiteTheDDDDt opened a new pull request, #63732:
URL: https://github.com/apache/doris/pull/63732
### What problem does this PR solve?
Issue Number: None
Related PR: None
Problem Summary: In a single-BE single-instance execution, non-distinct
aggregation does not benefit from splitting into local and global phases. The
split can add an unnecessary hash exchange and extra aggregate operator for
high-cardinality group-by queries. This change detects the single execution
instance case during Nereids non-distinct aggregate implementation and only
generates the one-phase aggregate candidate. It also lets the global aggregate
request ANY child distribution in that case so the optimizer does not add a
redundant exchange.
### Release note
Optimize aggregation planning for single-BE single-instance execution by
avoiding unnecessary local/global aggregate split.
### Check List (For Author)
- Test: FE Unit Test
- ./run-fe-ut.sh --run
org.apache.doris.nereids.rules.implementation.BucketedAggregateTest,org.apache.doris.nereids.properties.RequestPropertyDeriverTest
- cd fe && mvn checkstyle:check -pl fe-core
- Behavior changed: Yes. Non-distinct aggregate in single-BE single-instance
execution uses a one-phase plan in auto agg phase.
- Does this need documentation: No
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