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Type:
Bug
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Status: Closed
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Priority:
Major
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Resolution: Fixed
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Affects Version/s: None
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Fix Version/s: 1.26.0
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Component/s: None
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Labels:None
Improve simplification of "<>" (not equals) predicates. The goal is to simplify "a <> 1 or a = 1" to "true".
Today we can simplify "a = 1 or a <> 1" to "true" (the same expression with the terms re-ordered) but we cannot simplify "a <> 1 or a = 1" to "true". The problem is this. The algorithm for simplifying "or" builds a up a list of predicates as it works left to right. After dealing with "a = 1" RexSimplifier has a predicate "a = 1" and therefore it can simplify the next predicate to anything that returns the right result over the possible inputs - which will not include a = 1 - and therefore 'a <> 1' can be simplified to 'true'.
But today, we can't take that approach with "a <> 1 or a = 1" because "a <> 1" cannot be represented as a single range. It needs two ranges - less than 1 or greater than 1. The fix is therefore to allow predicates to be range sets not just ranges.
- is related to
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CALCITE-3852 RexSimplify doesn't simplify NOT EQUAL predicates
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- Closed
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