</para>

<para>

The default GIN operator class for <type>jsonb</type> supports queries with

top-level key-exists operators <literal>?</literal>, <literal>?&amp;</literal>

and <literal>?|</literal> operators and path/value-exists operator

<literal>@&gt;</literal>.

the key-exists operators <literal>?</literal>, <literal>?|</literal>

and <literal>?&amp;</literal>, the containment operator

<literal>@&gt;</literal>, and the <type>jsonpath</type> match

operators <literal>@?</literal> and <literal>@@</literal>.

(For details of the semantics that these operators

implement, see <xref linkend="functions-jsonb-op-table"/>.)

An example of creating an index with this operator class is:

<programlisting>

CREATE INDEX idxgin ON api USING GIN (jdoc);

</programlisting>

The non-default GIN operator class <literal>jsonb_path_ops</literal>

supports indexing the <literal>@&gt;</literal> operator only.

does not support the key-exists operators, but it does support

<literal>@&gt;</literal>, <literal>@?</literal> and <literal>@@</literal>.

An example of creating an index with this operator class is:

<programlisting>

CREATE INDEX idxginp ON api USING GIN (jdoc jsonb_path_ops);

(More information on expression indexes can be found in <xref

linkend="indexes-expressional"/>.)

</para>

<para>

Also, GIN index supports <literal>@@</literal> and <literal>@?</literal>

operators, which perform <literal>jsonpath</literal> matching.

<programlisting>

SELECT jdoc->'guid', jdoc->'name' FROM api WHERE jdoc @@ '$.tags[*] == "qui"';

</programlisting>

<programlisting>

SELECT jdoc->'guid', jdoc->'name' FROM api WHERE jdoc @? '$.tags[*] ? (@ == "qui")';

</programlisting>

GIN index extracts statements of following form out of

<literal>jsonpath</literal>: <replaceable>accessors_chain</replaceable> = <replaceable>const</replaceable>.

Accessors chain may consist of <literal>.key</literal>,

<literal>[*]</literal>, and <literal>[<replaceable>index</replaceable>]</literal> accessors.

<literal>jsonb_ops</literal> additionally supports <literal>.*</literal>

and <literal>.**</literal> accessors.

</para>

<para>

Another approach to querying is to exploit containment, for example:

<programlisting>

index.

</para>

<para>

GIN indexes also support the <literal>@?</literal>

and <literal>@@</literal> operators, which

perform <type>jsonpath</type> matching. Examples are

<programlisting>

SELECT jdoc->'guid', jdoc->'name' FROM api WHERE jdoc @? '$.tags[*] ? (@ == "qui")';

</programlisting>

<programlisting>

SELECT jdoc->'guid', jdoc->'name' FROM api WHERE jdoc @@ '$.tags[*] == "qui"';

</programlisting>

For these operators, a GIN index extracts clauses of the form

<literal><replaceable>accessors_chain</replaceable>

= <replaceable>constant</replaceable></literal> out of

the <type>jsonpath</type> pattern, and does the index search based on

the keys and values mentioned in these clauses. The accessors chain

may include <literal>.<replaceable>key</replaceable></literal>,

<literal>[*]</literal>,

and <literal>[<replaceable>index</replaceable>]</literal> accessors.

The <literal>jsonb_ops</literal> operator class also

supports <literal>.*</literal> and <literal>.**</literal> accessors,

but the <literal>jsonb_path_ops</literal> operator class does not.

</para>

<para>

Although the <literal>jsonb_path_ops</literal> operator class supports

only queries with the <literal>@&gt;</literal>, <literal>@@</literal>

and <literal>@?</literal> operators, it has notable

only queries with the <literal>@&gt;</literal>, <literal>@?</literal>

and <literal>@@</literal> operators, it has notable

performance advantages over the default operator

class <literal>jsonb_ops</literal>. A <literal>jsonb_path_ops</literal>

index is usually much smaller than a <literal>jsonb_ops</literal>