en abbreviated as
   <em class="firstterm">subxact</em>.
  </p><p>
   Subtransactions can be started explicitly using the
   <code class="command">SAVEPOINT</code> command, but can also be started in
   other ways, such as PL/pgSQL's <code class="command">EXCEPTION</code> clause.
   PL/Python and PL/Tcl also support explicit subtransactions.
   Subtransactions can also be started from other subtransactions.
   The top-level transaction and its child subtransactions form a
   hierarchy or tree, which is why 