title: Which is faster "where col = ? or col = ? or col = ?" OR "where col in (?, ?, ?)" in C with informix (.ec/esql)?
body: <p>Our code is written in C and DB is Informix. 
  We are doing some code optimization in ESQL program and found the following query:</p>
  
  <p><strong>UPDATE [TABLE] SET [PRIMARY KEY COLUMN] = [NEW KEY] WHERE COL = ? OR COL = ? ...</strong></p>
  
  <p>The number of columns in the where clause is dynamically prepared. We have an upper count check to stop preparing the where clause and do an update, then come back and start preparing the remaining. The UPPER_MARK is "30"</p>
  
  <p><strong>if ( where_parameter_count >= UPPER_MARK )</strong><br>
  __    execute update__<br>
  __    clean_and_continue; /* start prepare again */__  </p>
  
  <p>We thought of replacing the WHERE .. OR with WHERE ... IN</p>
  
  <p><strong>UPDATE [TABLE] SET [PRIMARY KEY COLUMN] = [NEW KEY] WHERE COL IN (?, ? ...)</strong></p>
  
  <p>Will this be faster than "where or"?</p>