*** a/doc/src/sgml/json.sgml
--- b/doc/src/sgml/json.sgml
*************** SELECT jdoc->'guid', jdoc->'name'
*** 453,458 ****
--- 453,463 ----
      particularly when queries contain keys that appear frequently in the
      data.  Therefore search operations typically perform better
      than with the default operator class.
+     <literal>jsonb_hash_ops</literal> indexes are ill-suited to cases
+     where there are frequent containment queries that test containment
+     of a <type>jsonb</> <emphasis>without</> any primitive object
+     values or array elements, as when searching for JSON documents
+     matching a particular structure.
    </para>
  
    <para>