sql/analyzer: indexed_joins: Use indexes in more cases where join condition includes AND ... IS [NOT] NULL. #473
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…dition includes AND ... IS [NOT] NULL.
reltuk
commented
Jun 16, 2021
| case *expression.Equals, *expression.NullSafeEquals: | ||
| switch e := expr.(type) { | ||
| case *expression.Equals, *expression.NullSafeEquals, *expression.IsNull: | ||
| case *expression.Not: |
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This works because getJoinIndex below is going to look for a complete index and then it's going to take the first partial index that matches. A partial index and applying the conjunction filter after the fact is the better path here.
It's not clear to me why we are so strict in the types of expressions we go after here...if there was an index that matched the expression a.blah LIKE b.like or whatever, wouldn't we want to use it just the same? Isn't any partial index on any portion of the conjunction still going to be correct and be better than no index at all?
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We could definitely loosen this up significantly, no reason to restrict it to only equality
zachmu
approved these changes
Jun 16, 2021
Hydrocharged
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aaron/indexed-join-uses-indexes-on-and-is-null
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