title: Creating index just for a query in Oracle 10g
body: <p>I have around 3.5 million records in a particular table in Oracle 10g and I want to query for all records with one particular column having NULL value.</p>
  
  <p>My question is, is it worth to create an index on that column just for the purpose of that one query? Will the time saved by using the index compensate the time taken to create it? Or should I just do the query without the index?</p>
  
  <p>Please note that I don't have the option to have the index created for me ahead of time and if I do create the index just for the query, I have to immediately drop it afterward.</p>
  
  <p>p/s: I did search for existing questions but can't find the answer I want. Do point me to any similar questions that I might have missed.</p>