title: Redshift ROW_ID column wrapping?
body: <p>Redshift's <code>ROW_ID</code> column is somewhat similar to PostgreSQL's <code>OID</code> column.
  That's a &quot;unique&quot; key for each record in a table, a hidden column added to each table.</p>
  <p>Would you expect <code>ROW_ID</code> to be wrapped at some point?</p>
  <p>In PostreSQL, <code>OID</code> column are 32 bits only -</p>
  <blockquote>
  <p>OIDs are implemented using 4-byte unsigned integers. They are not
  unique–OID counter will wrap around at 2³²-1. OID are also used to
  identify data types (see
  /usr/include/postgresql/server/catalog/pg_type_d.h).</p>
  </blockquote>
  <p>Because of the wrapping, OIDs in PostgreSQL are not truly unique.</p>
  <p>What's scale of <code>ROW_ID</code> in RedShift? Are they expected to be wrapped at some point? Can we expect <code>ROW_ID</code> to be unique? To be monotonically increasing?</p>
  <p>Can't find documentation on this.</p>
  <p>ps. <code>ROW_ID</code> is documented at least here <a href="https://docs.amazonaws.cn/en_us/redshift/latest/dg/c_load_compression_hidden_cols.html" rel="nofollow noreferrer">https://docs.amazonaws.cn/en_us/redshift/latest/dg/c_load_compression_hidden_cols.html</a> but it might has been removed in later versions of Redshift? Thanks</p>