Minor: move resolve_overlap a method on OrderingEquivalenceClass
#14138
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alamb
commented
Jan 15, 2025
| /// Trims `orderings[idx]` if some suffix of it overlaps with a prefix of | ||
| /// `orderings[pre_idx]`. Returns `true` if there is any overlap, `false` otherwise. | ||
| /// | ||
| /// For example, if `orderings[idx]` is `[a ASC, b ASC, c DESC]` and |
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I also added a small example
alamb
commented
Jan 16, 2025
| fn resolve_overlap(&mut self, idx: usize, pre_idx: usize) -> bool { | ||
| let length = self.orderings[idx].len(); | ||
| let other_length = self.orderings[pre_idx].len(); | ||
| for overlap in 1..=length.min(other_length) { |
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FWIW I think this is a very hot path in the particular queries. as it is something like O(N^3) in the number of potential sort orders. I am still investigating
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Which issue does this PR close?
UNIONandORDER BYqueries #13748Rationale for this change
I am testing out a change to the internal representation of
OrderingEquivalenceClassin #14136 and this method turns out to basically be an implementation detail.To make the job easier, let's make it a method on
OrderingEquivalenceClassWhat changes are included in this PR?
OrderingEquivalenceClassAre these changes tested?
By CI
Are there any user-facing changes?
No, this is entirely code movement