[CALCITE-4241] Some improvements to metadata query - #2146
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| return RelMdUtil.areColumnsDefinitelyUniqueWhenNullsFiltered(mq, leftRel, | ||
| return RelMdUtil.areColumnsDefinitelyUnique(mq, leftRel, | ||
| joinInfo.leftSet()); | ||
| } |
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RelMdUtil#areColumnsDefinitelyUniqueWhenNullsFiltered has different implementation from RelMdUtil#areColumnsDefinitelyUnique. The former one would ignore null while the other one not. Why do you say they have same behavoirs?
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@chunweilei Thanks a lot for your careful review. They are different indeed.
However, areColumnsDefinitelyUniqueWhenNullsFiltered methods could be implemented in a more efficient way.
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| + ") t(c1, c2, c3)"); | ||
| final RelMetadataQuery mq = rel.getCluster().getMetadataQuery(); | ||
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| ImmutableBitSet groupKey = ImmutableBitSet.of(0, 1, 2); |
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Could you add a test case which contains null literal?
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Sure. Cases for null literals are added. Thanks for your good suggestion.
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For {{RelMdColumnUniqueness#areColumnsUnique(RelSubset, RelMetadataQuery,
ImmutableBitSet, boolean)}}, we can return early as we encounter the first null.
For {{RelMdDistinctRowCount#getDistinctRowCount(Values, RelMetadataQuery,
ImmutableBitSet, RexNode)}}, we can get the distinct row count accurately, instead of guessing that half of the elements are distinct.
RelMdUtil#areColumnsDefinitelyUniqueWhenNullsFiltered could be implemented in a more efficient way.