title: How Pragma UDF works?
body: <p>Recently, I have read about UDF Pragma optimization method in Oracle Database 12. </p>
  
  <p>I'm very interested in how exactly it works. I've only found very short description in the <a href="https://docs.oracle.com/database/121/LNPLS/udf_pragma.htm#LNPLS1851" rel="noreferrer">Oracle documentation</a>. </p>
  
  <p>As I understand, every Pragma in PL/SQL is some kind of compiler directive (I could be wrong here) similar to <a href="https://docs.microsoft.com/en-us/cpp/preprocessor/pragma-directives-and-the-pragma-keyword?view=vs-2017" rel="noreferrer">C++ Pragma Directives</a>. </p>
  
  <p>Maybe someone can explain to me in more details (or provide links :) ) how the internal mechanism of UDF Pragma works?</p>