title: Update BigQuery permanent external tables
body: <p>I'm using BigQuery both to store data within &quot;native&quot; BigQuery tables and to query data stored in Google Cloud Storage. According to the documentation, it is possible to query external sources using two types of tables: <em>permanent</em> and <em>temporary</em> external tables.<br />
  Consider the following scenario: every day some parquet files are written in GCS, and with a certain frequency I want to do a JOIN between the data stored in a BigQuery table and the data stored in parquet files. If I create a <em>permanent</em> external table, and then I update the files below, is the content of the table automatically updated as well, or do I have to recreate it from the new files?
  What are the best practices for such a scenario?</p>