title: Is leftsemi faster with smaller table on the left side?
body: <p><a href="https://docs.microsoft.com/en-us/azure/data-explorer/kusto/query/joinoperator?pivots=azuredataexplorer" rel="nofollow noreferrer">Join operator</a> documentation says:</p>
  <blockquote>
  <p>Tip</p>
  <p>For best performance, if one table is always smaller than the
  other, use it as the left (piped) side of the join.</p>
  </blockquote>
  <p>The purpose of <a href="https://docs.microsoft.com/en-us/azure/data-explorer/kusto/query/joinoperator?pivots=azuredataexplorer#left-semi-join-flavor" rel="nofollow noreferrer">leftsemi</a> in most cases is to filter a bigger set on the left by a smaller set on the right. Is the quote above still applicable to <code>leftsemi</code> flavor of join operator?</p>