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Fix to #16078 - Query/Null semantics: when checking if expression is null, just check it's constituents rather than entire expression #18560

Merged
merged 1 commit into from
Oct 24, 2019
Merged

Fix to #16078 - Query/Null semantics: when checking if expression is null, just check it's constituents rather than entire expression #18560

merged 1 commit into from
Oct 24, 2019

Commits on Oct 24, 2019

  1. Fix to #16078 - Query/Null semantics: when checking if expression is … 

    …null, just check it's constituents rather than entire expression

Problem was that during null semantics rewrite we create IS NULL calls on the operands of the comparison. If the operands themselves are complicated, we were simply comparing the entire complex expression to null. In some cases, we only need to look at constituents, e.g. a + b == null <=> a == null || b == null.

Also added other minor optimizations around null semantics:

- non_nullable_column IS NULL resolves to false,
- try to simplify expression after applying de Morgan transformations

Also fixed a bug exposed by these changes, where column nullability would be incorrect for scenarios with owned types.
    @maumar
    maumar committed Oct 24, 2019
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