Is the query engine always smart enough to know when to generate an internal CTE on a query?

We've got a long-running query that has a tendency to get canceled because it hits our temporary storage threshold.

The current table has a lot of conditions in the WHERE clause on the primary table that greatly narrow the rows from that table.  There are also 15 left joins on that primary table.  I've thought about modifying the query to use a CTE on the primary table and move the conditions in the WHERE clause to the CTE.

I'm just wondering if the query engine optimizes this anyway without the explicit CTE.  Thoughts?

- Dan Bale
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