Does SQL Server cache scalar function results when used simultaneously in SELECT, WHERE and GROUP BY?

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Consider this contrived example:

SELECT
    Foo,
    dbo.ExpensiveScalarFunction( Bar ),
    COUNT(*)
FROM
    Source
WHERE
    dbo.ExpensiveScalarFunction( Bar ) <> 'abc'
GROUP BY
    Foo,
    dbo.ExpensiveScalarFunction( Bar )
HAVING
    dbo.ExpensiveScalarFunction( Bar ) > 'abd'

Would ExpensiveScalarFunction be evaluated 4 times for each row, or only once? Is SQL Server able to identify that the function is deterministic and optimize for that case?

asked 21 secs ago

Dai

28.3k

Does SQL Server cache scalar function results when used simultaneously in SELECT, WHERE and GROUP BY?