aggregate_statistics should only optimize MIN/MAX when relation is not empty #8914
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viirya
commented
Jan 19, 2024
| .as_any() | ||
| .downcast_ref::<expressions::Column>() | ||
| if let Precision::Exact(num_rows) = &stats.num_rows { | ||
| if *num_rows > 0 { |
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We could optimize MIN/MAX if the relation is empty (i.e., return NULL directly). Since it is not the issue itself, I will leave it as follow up.
9 tasks
alamb
approved these changes
Jan 19, 2024
| @@ -3260,3 +3260,19 @@ query I | |||
| select count(*) from (select count(*) a, count(*) b from (select 1)); | |||
| ---- | |||
| 1 | |||
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Can we also add another test where there is a single row that doesn't actually pass the predicate?
Like
CREATE TABLE t(col0 INTEGER) as VALUES(2);
SELECT MIN(col0) FROM empty WHERE col0=1;
SELECT MAX(col0) FROM empty WHERE col0=1;
So the table is not actually empty but the filter removes it all
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Good idea. Added that one.
|
Thank you @alamb |
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Which issue does this PR close?
Closes #8911.
Rationale for this change
What changes are included in this PR?
Are these changes tested?
Are there any user-facing changes?