title: mysql: unique constraint on big table
body: <p>Hi I would like to hear some comments or experience on having a unique constraint on multiple columns(4 columns) on a big table and index on individual columns and the table gets updated very frequently, I am using mysql database and the unique constraint is required for frequent reads and individual column index is also used at other parts of the application read. will it have any side effect in future, it will maximum have of 1-2 million records.</p>
  <p>The indexes are inevitable and kindly suggest me is it right to do and also I would like to know this table gets updated frequently, is there anything can be done at the  database level to prevent deadlocks.</p>