title: Is using a unique datetime or timestamp for database records a bad idea?
body: <p>I'm fairly new to the SQL world and am designing a database that will record real-time data at up to 32Hz.  It seems logical to use the timestamp as part of the primary key, or at least to make it unique (and perhaps composite with other information).  My question is about performance as the size of the table increases.  Naively, I'm thinking that if the database must check the timestamp is unique everytime I insert a record, things will get really slow after a while.  But then again this is probably something database optimizers solved years ago and it's perfectly efficient to define timestamp as unique on large scale databases.</p>
  
  <p>Note I'm using MySQL and timestamp for my database.  Also I don't actually need timestamp to be unique, it just makes me feel better knowing the schema is as tightly defined as possible.</p>