The unwrapping behavior of lax mode can lead to surprising results. For

instance, the following query using the <literal>.**</literal> accessor

selects every <literal>HR</literal> value twice:

<screen>

<prompt>=&gt;</prompt> <userinput>select jsonb_path_query(:'json', 'lax $.**.HR');</userinput>

jsonb_path_query

------------------

73

135

73

135

</screen>

<screen>

<prompt>=&gt;</prompt> <userinput>select jsonb_path_query(:'json', 'lax $.**.HR');</userinput>

jsonb_path_query

------------------

73

135

73

135

</screen>

This happens because the <literal>.**</literal> accessor selects both

the <literal>segments</literal> array and each of its elements, while

the <literal>.HR</literal> accessor automatically unwraps arrays when

using lax mode. To avoid surprising results, we recommend using

the <literal>.**</literal> accessor only in strict mode. The

following query selects each <literal>HR</literal> value just once:

<screen>

<prompt>=&gt;</prompt> <userinput>select jsonb_path_query(:'json', 'strict $.**.HR');</userinput>

jsonb_path_query

------------------

73

135

</screen>

<screen>

<prompt>=&gt;</prompt> <userinput>select jsonb_path_query(:'json', 'strict $.**.HR');</userinput>

jsonb_path_query

------------------

73

135

</screen>

</para>

<para>

now only choose one of these two commands, since all other commands

will be ignored:

<programlisting>

ROLLBACK;

ROLLBACK TO SAVEPOINT sp1;

ROLLBACK;

ROLLBACK TO SAVEPOINT sp1;

</programlisting>

Choosing <command>ROLLBACK</command> will abort everything, including

value 1, whereas <command>ROLLBACK TO SAVEPOINT sp1</command> will retain