Just a quick followup. I did some experimenting and found similar results to yours, even with updating the stats. One thing you should be aware of, however, is that the scalar subquery is not equivalent to
Quote:
select col_id, col_a, col_b, col_x, ... col_n
from table_1 t1, table_2 t2, ...
where t1.col_id = t2.col_id and ...
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It is equivalent to an outer join and not an equijoin. This can affect your results, depending on the data of course.