title: MySQL VARCHAR index truncated to 255 during migration
body: <p>I am a little confused as to what happens in this situation.  We have a column that is, say, VARCHAR(500) in SQL Server.  The migration tool ( MySQL Workbench ) truncates the index to 255.  This other <a href="https://stackoverflow.com/questions/27829152/force-truncation-on-varchar-modification">post</a> I found, plus many other places on Google, suggest that 255 is the limit for VARCHAR based indexes.  From this <a href="https://stackoverflow.com/a/16474039/3329922">post here</a>, I see that it is the first 255 characters.  But I am sort of confused as to how that works out in actual practice.  In other words, if, by dumb luck, I am looking for a substring ( using the "like" clause ) that is after the 255 point in the real column, what would happen?  Or what would happen if I compare the column using "=", ">", etc, but use more than 255 in comparison string.  In these kind of screwy situations, does it just ignore the index, or what?</p>
  
  <p>Sort of new to MySQL, been working with SQL Server for years, so just trying to understand what to expect.  Thanks.</p>