+=item C<db_query $query, %params>
+
+Executes an SQL query. The following parameters are supported:
+
+=over 2
+
+=item C<may_fail>
+
+What the method does if the query fails depends on this parameter. If
+it is falsish (the default) then the method will simply die outputting
+the error message via L</db_error>. If C<may_fail> is trueish then the
+current transaction will be rolled back, a new one will be started.
+
+=item C<bind>
+
+An optional array reference containing bind parameter for the query.
+
+=item C<dbh>
+
+The database handle to use. If undefined then C<$self-E<gt>dbh> will
+be used.
+
+=back
+
+=item C<db_errstr [$handle]>
+
+Returns the last database from C<$handle> error message encoded in
+Perl's internal encoding. The PostgreSQL DBD leaves the UTF-8 flag off
+for error messages even if the C<pg_enable_utf8> attribute is set.
+
+C<$handle> is optional and can be one of three things:
+
+=over 2
+
+=item 1. A database or statement handle. In that case
+C<$handle-E<gt>errstr> is used.
+
+=item 2. The string 'DBI'. In that case C<$DBI::errstr> is used.