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    <ol> <li>The difference between (a) using FORCE and (b) using EXACT and coding bind variable yourself, is that in the latter case you control when bind variables are used. So if you can see that in a particular case bind variables are hurting performance, or aren't necessary, you can change that query. With FORCE, you're stuck. The reason that bind variables are recommended <em>for OLTP type queries</em> is that parsing is a highly serialized process that can become a big bottleneck. In OLTP systems you tend to see lots of queries that should always be using the same execution plan run with different values, so re-parsing them all the time is a waste. Any good source will also recommend that you consider when to not use bind variables -- for instance, if you only have a few possible values that can appear at a particular position in a query, and one or more of those values might benefit from a different execution plan, it may be better overall to use literals since you can parse each variant once and then reuse the cached plan.</li> </ol> <p>(Another benefit to using bind variables is that it leaves you less open to SQL injection.)</p> <p>2 &amp; 3. Histograms are used in general when creating execution plans for queries, and in more ways than are obvious. Yes, in the case of a standard bind variable peek with EXACT setting, the histogram is (or at least, may be) used by the optimizer in determining the execution plan. This can be a good thing or a bad thing, depending on the skew and what particular value you have for the bind. I think the point your source is making about histograms and the SIMILAR setting is that in that case, the presence of the histogram is one of the triggers that will cause a new execution plan to be created.</p> <p>(I would highly recommend Jonathan Lewis's "Cost-Based Oracle Fundamentals" for all the information you could want about when and how histograms are used.)</p> <p>4.. I believe that Adaptive Cursor Sharing is essentially an enhanced version of the logic that was previously implemented for CURSOR_SHARING=SIMILAR. The optimizer will consider creating new plans based on bind variable peeking, in all circumstances. SIMILAR appears to still exist as an option. <a href="http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:599762300346943686" rel="noreferrer">This post</a> may provide some further helpful info.</p>
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    1. CO+1 for a nice answer and the tip on the book.
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    2. COThank you for answering this question so thoroughly. Much appreciated!
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