englefly opened a new pull request, #18607:
URL: https://github.com/apache/doris/pull/18607
# Proposed changes
`select count(*) from T group by A, B`
the estimated row count of aggregate is between `ndv(A)` and `ndv(A) *
ndv(B)`
in previous version, we choose upper bound, that is `ndv(A) * ndv(B)`. The
drawback of this choice is the estimated row is often bigger that row count of
T.
In this version, we choose the lower bound.
Issue Number: close #xxx
## Problem summary
Describe your changes.
## Checklist(Required)
* [ ] Does it affect the original behavior
* [ ] Has unit tests been added
* [ ] Has document been added or modified
* [ ] Does it need to update dependencies
* [ ] Is this PR support rollback (If NO, please explain WHY)
## Further comments
If this is a relatively large or complex change, kick off the discussion at
[[email protected]](mailto:[email protected]) by explaining why you
chose the solution you did and what alternatives you considered, etc...
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