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GIN support for @@ and @? jsonpath operators

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This commit makes existing GIN operator classes jsonb_ops and json_path_ops
support "jsonb @@ jsonpath" and "jsonb @? jsonpath" operators.  Basic idea is
to extract statements of following form out of jsonpath.

 key1.key2. ... .keyN = const

The rest of jsonpath is rechecked from heap.

Catversion is bumped.

Discussion: https://postgr.es/m/fcc6fc6a-b497-f39a-923d-aa34d0c588e8%402ndQuadrant.com
Author: Nikita Glukhov, Alexander Korotkov
Reviewed-by: Jonathan Katz, Pavel Stehule
This commit is contained in:
Alexander Korotkov
2019-04-01 18:08:15 +03:00
parent 7241911782
commit 0a02e2ae02
11 changed files with 1457 additions and 79 deletions
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19
doc/src/sgml/json.sgml
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@ -480,6 +480,22 @@ CREATE INDEX idxgintags ON api USING GIN ((jdoc -> 'tags'));
(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>: <literal>accessors_chain = const</literal>.
Accessors chain may consist of <literal>.key</literal>,
<literal>[*]</literal> and <literal>[index]</literal> accessors.
<literal>jsonb_ops</literal> additionally supports <literal>.*</literal>
and <literal>.**</literal> statements.
</para>
<para>
Another approach to querying is to exploit containment, for example:
<programlisting>
@ -498,7 +514,8 @@ SELECT jdoc-&gt;'guid', jdoc-&gt;'name' FROM api WHERE jdoc @&gt; '{"tags": ["qu
<para>
Although the <literal>jsonb_path_ops</literal> operator class supports
only queries with the <literal>@&gt;</literal> operator, 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>