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recommendation for comparing strings and numbers (#12442)
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vtlim committed Apr 18, 2022
1 parent 5167d32 commit c86c48203edf67a696a6e64c677a4792ff26079e
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@@ -67,6 +67,21 @@ The WHERE clause refers to columns in the FROM table, and will be translated to
WHERE clause can also reference a subquery, like `WHERE col1 IN (SELECT foo FROM ...)`. Queries like this are executed
as a join on the subquery, described in the [Query translation]( section.

Strings and numbers can be compared in the WHERE clause of a SQL query through implicit type conversion.
For example, you can evaluate `WHERE stringDim = 1` for a string-typed dimension named `stringDim`.
However, for optimal performance, you should explicitly cast the reference number as a string when comparing against a string dimension:
WHERE stringDim = '1'

Similarly, if you compare a string-typed dimension with reference to an array of numbers, cast the numbers to strings:
WHERE stringDim IN ('1', '2', '3')

Note that explicit type casting does not lead to significant performance improvement when comparing strings and numbers involving numeric dimensions since numeric dimensions are not indexed.


The GROUP BY clause refers to columns in the FROM table. Using GROUP BY, DISTINCT, or any aggregation functions will

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