villebro commented on issue #8074: Common Table Expressions (CTE's) do not work for Microsoft SQL Server database URL: https://github.com/apache/incubator-superset/issues/8074#issuecomment-526344999 Looking more closely at this problem, it seems MSSQL is one of the few engines that doesn't support wrapping CTEs in subqueries (even Oracle supports this). Furthermore, most engines do equal predicate pushdown for CTEs and subqueries, which means that wrapping SQL Lab queries in CTEs in most cases wouldn't have a significant positive performance impact (on Postgres 11 and below CTEs actually perform worse than subqueries!). As this problem seems to be mostly an MSSQL problem, I think I'll leave this on the backlog for now, as making this work correctly would require a rather significant development effort that's difficult to justify given other more pressing issues/features.
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