title: How does Big Query store millions of rows of a column with categorical (duplicate) string values?
body: <p>We are streaming around a million records per day into BQ and a particular string column has categorical values of "High", "Medium" and "Low".</p>
  
  <p>I am trying to understand if Biq Query does storage optimisations other than compression at its own end and what is the scale of that? Looked for documentation on this and was unable to find explanations on the same.</p>
  
  <p>For example if i have:</p>
  
  <pre><code>**Col1**
  High
  High
  Medium
  Low
  High
  Low
  **... 100 Million Rows**
  </code></pre>
  
  <p>Would BQ Store it internally as follows</p>
  
  <pre><code>**Col1**
  1
  1
  2
  3
  1
  3
  **... 100 Million Rows**
  </code></pre>