SELECT DISTINCT or SELECT efficiency for IN clause
<p>Using Oracle (if that matters).  Both of these Select statements will produce the same end result, but which one is quicker?</p>

<pre><code>SELECT * FROM tbl_A WHERE val IN (SELECT myField FROM tbl_B WHERE ... );
</code></pre>

<p>or would a SELECT DISTINCT in the sub-query be better?</p>

<pre><code>SELECT * FROM tbl_A WHERE val IN (SELECT DISTINCT myField FROM tbl_B WHERE ... );
</code></pre>

<p>Thanks!</p>