 Hash indexes
      </span></dt><dd><p>
        Share/exclusive hash-bucket-level locks are used for read/write
        access.  Locks are released after the whole bucket is processed.
        Bucket-level locks provide better concurrency than index-level
        ones, but deadlock is possible since the locks are held longer
        than one index operation.
       </p></dd><dt><span class="term">
       <acronym class="acronym">GIN</acronym> indexes
      </span></dt><dd><p>
        Short-term share/exclus