Does Oracle use short-circuit evaluation?

Question

I have an Oracle query that is structured as followed:

SELECT   *
FROM     table
WHERE    X=\'true\' OR
         Y IN (complicated subquery)

<

Answer 1

Regardless of what the optimizer may or may not do with AND and OR, if for any reason you must enforce a specific order of evaluation, you can rewrite the query, using other tools where short-circuit evaluation is guaranteed.

For example:

select * from table 1
where case when X = 'true' then 1
           when Y in (select ....)   then 1
      end  = 1

If X is 'true' then the case expression evaluates to 1, the second "when" is skipped and the condition evaluates to TRUE. If X is not 'true' then the IN condition is evaluated.