fix/perf: Optimize ~! '.*' case to False instead of Eq ""#20702
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petern48 wants to merge 3 commits intoapache:mainfrom
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fix/perf: Optimize ~! '.*' case to False instead of Eq ""#20702petern48 wants to merge 3 commits intoapache:mainfrom
~! '.*' case to False instead of Eq ""#20702petern48 wants to merge 3 commits intoapache:mainfrom
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petern48
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False instead of Eq ""~! '.*' case to False instead of Eq ""
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| /// - combinations (alternatives) of the above, will be concatenated with `OR` or `AND` | ||
| /// - `EQ .*` to NotNull | ||
| /// - `NE .*` means IS EMPTY | ||
| /// - `NE .*` to false (.* matches non-empty and empty strings, and NULL !~ '.*' results in NULL so this can never be true) |
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I think it is only false in the context of filters (and this code can currently be used for both filters and regular expressions)
I think null !~ '.*' is actually null (not false)
I think a correct rewrite is
CASE
WHEN col IS NOT NULL THEN FALSE
ELSE NULL
END| )?; | ||
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| // Test `!= ".*"` transforms to checking if the column is empty | ||
| // Test `!~ ".*"` transforms to false |
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can we please also add a test explicitly for a null input?
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Which issue does this PR close?
.*pattern toEq ""operation #20701Rationale for this change
What changes are included in this PR?
A pre-existing optimization rule for the
!~ .*(regexp not match) case rewrote the plan toEq "", which would return empty strings as part of the result. This is incorrect and doesn't match the output without the optimization rule.Instead, this PR rewrites the plan to simply
lit(false). The reasoning why it's always false is as follows:.*pattern matches all strings including empty strings (""), so empty strings should not be returnedNULL !~ .*evaluates toNULL(hence not true), so the query also doesn't return null rows.I've confirmed this behavior matches the result of running queries manually with the optimization rule turned off.
Are these changes tested?
Fixed expected output in tests.
Are there any user-facing changes?
Yes, a minor bug fix. When querying
s !~ .*, empty strings will no longer be included in the result which is consistent with the behavior without the optimization rule.