title: mysql view table performance
body: <p>I just want to confirm</p>
  
  <p>so i have 2 tables with exact same columns but different content
  let's say table A and B
  and i'm creating view table AB which is simply</p>
  
  <pre><code>select * from a
  union
  select * from b
  </code></pre>
  
  <p>when the data of each table gets big like millions will </p>
  
  <pre><code>select * from ab where `value`&gt;1000
  </code></pre>
  
  <p>be as fast as</p>
  
  <pre><code>select * from a where `value`&gt;1000
  union
  select * from b where `value`&gt;1000
  </code></pre>
  
  <p>now the data is just several thousands so i don't have any issue at all</p>