作者
digoal
日期
2022-03-28
标签
PostgreSQL , JSON , SQL/JSON
新增了几个json构造函数.
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=f79b803dcc98d707450e158db3638dc67ff8380b
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=f4fb45d15c59d7add2e1b81a9d477d0119a9691a
SQL/JSON constructors
author Andrew Dunstan <andrew@dunslane.net>
Thu, 3 Mar 2022 18:02:10 +0000 (13:02 -0500)
committer Andrew Dunstan <andrew@dunslane.net>
Sun, 27 Mar 2022 21:03:34 +0000 (17:03 -0400)
commit f4fb45d15c59d7add2e1b81a9d477d0119a9691a
tree 9025afb61fd4409ae48cd21d47c7fd58647e2633 tree
parent f79b803dcc98d707450e158db3638dc67ff8380b commit | diff
SQL/JSON constructors
This patch introduces the SQL/JSON standard constructors for JSON:
JSON()
JSON_ARRAY()
JSON_ARRAYAGG()
JSON_OBJECT()
JSON_OBJECTAGG()
For the most part these functions provide facilities that mimic
existing json/jsonb functions. However, they also offer some useful
additional functionality. In addition to text input, the JSON() function
accepts bytea input, which it will decode and constuct a json value from.
The other functions provide useful options for handling duplicate keys
and null values.
This series of patches will be followed by a consolidated documentation
patch.
Nikita Glukhov
Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.
Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
使用举例:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/test/regress/expected/sqljson.out;h=7dca5a8a30f408ebbde215b37ef511c0823222f1;hb=f4fb45d15c59d7add2e1b81a9d477d0119a9691a
支持is json 语法:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=33a377608fc29cdd1f6b63be561eab0aee5c81f0
IS JSON predicate
This patch intrdocuces the SQL standard IS JSON predicate. It operates
on text and bytea values representing JSON as well as on the json and
jsonb types. Each test has an IS and IS NOT variant. The tests are:
IS JSON [VALUE]
IS JSON ARRAY
IS JSON OBJECT
IS JSON SCALAR
IS JSON WITH | WITHOUT UNIQUE KEYS
These are mostly self-explanatory, but note that IS JSON WITHOUT UNIQUE
KEYS is true whenever IS JSON is true, and IS JSON WITH UNIQUE KEYS is
true whenever IS JSON is true except it IS JSON OBJECT is true and there
are duplicate keys (which is never the case when applied to jsonb values).
+-- IS JSON predicate
+SELECT NULL IS JSON;
+ ?column?
+----------
+
+(1 row)
+
+SELECT NULL IS NOT JSON;
+ ?column?
+----------
+
+(1 row)
+
+SELECT NULL::json IS JSON;
+ ?column?
+----------
+
+(1 row)
+
+SELECT NULL::jsonb IS JSON;
+ ?column?
+----------
+
+(1 row)
+
+SELECT NULL::text IS JSON;
+ ?column?
+----------
+
+(1 row)
+
+SELECT NULL::bytea IS JSON;
+ ?column?
+----------
+
+(1 row)
+
+SELECT NULL::int IS JSON;
+ERROR: cannot use type integer in IS JSON predicate
+SELECT '' IS JSON;
+ ?column?
+----------
+ f
+(1 row)
+
+SELECT bytea '\x00' IS JSON;
+ERROR: invalid byte sequence for encoding "UTF8": 0x00
+CREATE TABLE test_is_json (js text);
+INSERT INTO test_is_json VALUES
+ (NULL),
+ (''),
+ ('123'),
+ ('"aaa "'),
+ ('true'),
+ ('null'),
+ ('[]'),
+ ('[1, "2", {}]'),
+ ('{}'),
+ ('{ "a": 1, "b": null }'),
+ ('{ "a": 1, "a": null }'),
+ ('{ "a": 1, "b": [{ "a": 1 }, { "a": 2 }] }'),
+ ('{ "a": 1, "b": [{ "a": 1, "b": 0, "a": 2 }] }'),
+ ('aaa'),
+ ('{a:1}'),
+ ('["a",]');
+SELECT
+ js,
+ js IS JSON "IS JSON",
+ js IS NOT JSON "IS NOT JSON",
+ js IS JSON VALUE "IS VALUE",
+ js IS JSON OBJECT "IS OBJECT",
+ js IS JSON ARRAY "IS ARRAY",
+ js IS JSON SCALAR "IS SCALAR",
+ js IS JSON WITHOUT UNIQUE KEYS "WITHOUT UNIQUE",
+ js IS JSON WITH UNIQUE KEYS "WITH UNIQUE"
+FROM
+ test_is_json;
+ js | IS JSON | IS NOT JSON | IS VALUE | IS OBJECT | IS ARRAY | IS SCALAR | WITHOUT UNIQUE | WITH UNIQUE
+-----------------------------------------------+---------+-------------+----------+-----------+----------+-----------+----------------+-------------
+ | | | | | | | |
+ | f | t | f | f | f | f | f | f
+ 123 | t | f | t | f | f | t | t | t
+ "aaa " | t | f | t | f | f | t | t | t
+ true | t | f | t | f | f | t | t | t
+ null | t | f | t | f | f | t | t | t
+ [] | t | f | t | f | t | f | t | t
+ [1, "2", {}] | t | f | t | f | t | f | t | t
+ {} | t | f | t | t | f | f | t | t
+ { "a": 1, "b": null } | t | f | t | t | f | f | t | t
+ { "a": 1, "a": null } | t | f | t | t | f | f | t | f
+ { "a": 1, "b": [{ "a": 1 }, { "a": 2 }] } | t | f | t | t | f | f | t | t
+ { "a": 1, "b": [{ "a": 1, "b": 0, "a": 2 }] } | t | f | t | t | f | f | t | f
+ aaa | f | t | f | f | f | f | f | f
+ {a:1} | f | t | f | f | f | f | f | f
+ ["a",] | f | t | f | f | f | f | f | f
+(16 rows)
+
+SELECT
+ js,
+ js IS JSON "IS JSON",
+ js IS NOT JSON "IS NOT JSON",
+ js IS JSON VALUE "IS VALUE",
+ js IS JSON OBJECT "IS OBJECT",
+ js IS JSON ARRAY "IS ARRAY",
+ js IS JSON SCALAR "IS SCALAR",
+ js IS JSON WITHOUT UNIQUE KEYS "WITHOUT UNIQUE",
+ js IS JSON WITH UNIQUE KEYS "WITH UNIQUE"
+FROM
+ (SELECT js::json FROM test_is_json WHERE js IS JSON) foo(js);
+ js | IS JSON | IS NOT JSON | IS VALUE | IS OBJECT | IS ARRAY | IS SCALAR | WITHOUT UNIQUE | WITH UNIQUE
+-----------------------------------------------+---------+-------------+----------+-----------+----------+-----------+----------------+-------------
+ 123 | t | f | t | f | f | t | t | t
+ "aaa " | t | f | t | f | f | t | t | t
+ true | t | f | t | f | f | t | t | t
+ null | t | f | t | f | f | t | t | t
+ [] | t | f | t | f | t | f | t | t
+ [1, "2", {}] | t | f | t | f | t | f | t | t
+ {} | t | f | t | t | f | f | t | t
+ { "a": 1, "b": null } | t | f | t | t | f | f | t | t
+ { "a": 1, "a": null } | t | f | t | t | f | f | t | f
+ { "a": 1, "b": [{ "a": 1 }, { "a": 2 }] } | t | f | t | t | f | f | t | t
+ { "a": 1, "b": [{ "a": 1, "b": 0, "a": 2 }] } | t | f | t | t | f | f | t | f
+(11 rows)
+
+SELECT
+ js0,
+ js IS JSON "IS JSON",
+ js IS NOT JSON "IS NOT JSON",
+ js IS JSON VALUE "IS VALUE",
+ js IS JSON OBJECT "IS OBJECT",
+ js IS JSON ARRAY "IS ARRAY",
+ js IS JSON SCALAR "IS SCALAR",
+ js IS JSON WITHOUT UNIQUE KEYS "WITHOUT UNIQUE",
+ js IS JSON WITH UNIQUE KEYS "WITH UNIQUE"
+FROM
+ (SELECT js, js::bytea FROM test_is_json WHERE js IS JSON) foo(js0, js);
+ js0 | IS JSON | IS NOT JSON | IS VALUE | IS OBJECT | IS ARRAY | IS SCALAR | WITHOUT UNIQUE | WITH UNIQUE
+-----------------------------------------------+---------+-------------+----------+-----------+----------+-----------+----------------+-------------
+ 123 | t | f | t | f | f | t | t | t
+ "aaa " | t | f | t | f | f | t | t | t
+ true | t | f | t | f | f | t | t | t
+ null | t | f | t | f | f | t | t | t
+ [] | t | f | t | f | t | f | t | t
+ [1, "2", {}] | t | f | t | f | t | f | t | t
+ {} | t | f | t | t | f | f | t | t
+ { "a": 1, "b": null } | t | f | t | t | f | f | t | t
+ { "a": 1, "a": null } | t | f | t | t | f | f | t | f
+ { "a": 1, "b": [{ "a": 1 }, { "a": 2 }] } | t | f | t | t | f | f | t | t
+ { "a": 1, "b": [{ "a": 1, "b": 0, "a": 2 }] } | t | f | t | t | f | f | t | f
+(11 rows)
+
+SELECT
+ js,
+ js IS JSON "IS JSON",
+ js IS NOT JSON "IS NOT JSON",
+ js IS JSON VALUE "IS VALUE",
+ js IS JSON OBJECT "IS OBJECT",
+ js IS JSON ARRAY "IS ARRAY",
+ js IS JSON SCALAR "IS SCALAR",
+ js IS JSON WITHOUT UNIQUE KEYS "WITHOUT UNIQUE",
+ js IS JSON WITH UNIQUE KEYS "WITH UNIQUE"
+FROM
+ (SELECT js::jsonb FROM test_is_json WHERE js IS JSON) foo(js);
+ js | IS JSON | IS NOT JSON | IS VALUE | IS OBJECT | IS ARRAY | IS SCALAR | WITHOUT UNIQUE | WITH UNIQUE
+-------------------------------------+---------+-------------+----------+-----------+----------+-----------+----------------+-------------
+ 123 | t | f | t | f | f | t | t | t
+ "aaa " | t | f | t | f | f | t | t | t
+ true | t | f | t | f | f | t | t | t
+ null | t | f | t | f | f | t | t | t
+ [] | t | f | t | f | t | f | t | t
+ [1, "2", {}] | t | f | t | f | t | f | t | t
+ {} | t | f | t | t | f | f | t | t
+ {"a": 1, "b": null} | t | f | t | t | f | f | t | t
+ {"a": null} | t | f | t | t | f | f | t | t
+ {"a": 1, "b": [{"a": 1}, {"a": 2}]} | t | f | t | t | f | f | t | t
+ {"a": 1, "b": [{"a": 2, "b": 0}]} | t | f | t | t | f | f | t | t
+(11 rows)
+
+-- Test IS JSON deparsing
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT '1' IS JSON AS "any", ('1' || i) IS JSON SCALAR AS "scalar", '[]' IS NOT JSON ARRAY AS "array", '{}' IS JSON OBJECT WITH UNIQUE AS "object" FROM generate_series(1, 3) i;
+ QUERY PLAN
+----------------------------------------------------------------------------------------------------------------------------------------------------------
+ Function Scan on pg_catalog.generate_series i
+ Output: ('1'::text IS JSON), (('1'::text || (i)::text) IS JSON SCALAR), (NOT ('[]'::text IS JSON ARRAY)), ('{}'::text IS JSON OBJECT WITH UNIQUE KEYS)
+ Function Call: generate_series(1, 3)
+(3 rows)
+
+CREATE VIEW is_json_view AS
+SELECT '1' IS JSON AS "any", ('1' || i) IS JSON SCALAR AS "scalar", '[]' IS NOT JSON ARRAY AS "array", '{}' IS JSON OBJECT WITH UNIQUE AS "object" FROM generate_series(1, 3) i;
+\sv is_json_view
+CREATE OR REPLACE VIEW public.is_json_view AS
+ SELECT '1'::text IS JSON AS "any",
+ ('1'::text || i.i) IS JSON SCALAR AS scalar,
+ NOT '[]'::text IS JSON ARRAY AS "array",
+ '{}'::text IS JSON OBJECT WITH UNIQUE KEYS AS object
+ FROM generate_series(1, 3) i(i)
+DROP VIEW is_json_view;
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=606948b058dc16bce494270eea577011a602810e
SQL JSON functions
This Patch introduces three SQL standard JSON functions:
JSON() (incorrectly mentioned in my commit message for f4fb45d15c)
JSON_SCALAR()
JSON_SERIALIZE()
JSON() produces json values from text, bytea, json or jsonb values, and
has facilitites for handling duplicate keys.
JSON_SCALAR() produces a json value from any scalar sql value, including
json and jsonb.
JSON_SERIALIZE() produces text or bytea from input which containis or
represents json or jsonb;
For the most part these functions don't add any significant new
capabilities, but they will be of use to users wanting standard
compliant JSON handling.
https://git.postgresql.org/gitweb/?p=postgresql.git;a=blobdiff;f=src/test/regress/expected/sqljson.out;h=11f5eb2d2cee3fa58054a1e592ec54b52c65d8c1;hp=27dca7815a72c284e4d2c438781d3b3e58c7d033;hb=606948b058dc16bce494270eea577011a602810e;hpb=8e053dc6dfbee4ae412e98ad73cfd4662d7453ac
+-- JSON()
+SELECT JSON();
+ERROR: syntax error at or near ")"
+LINE 1: SELECT JSON();
+ ^
+SELECT JSON(NULL);
+ json
+------
+
+(1 row)
+
+SELECT JSON('{ "a" : 1 } ');
+ json
+--------------
+ { "a" : 1 }
+(1 row)
+
+SELECT JSON('{ "a" : 1 } ' FORMAT JSON);
+ json
+--------------
+ { "a" : 1 }
+(1 row)
+
+SELECT JSON('{ "a" : 1 } ' FORMAT JSON ENCODING UTF8);
+ERROR: JSON ENCODING clause is only allowed for bytea input type
+LINE 1: SELECT JSON('{ "a" : 1 } ' FORMAT JSON ENCODING UTF8);
+ ^
+SELECT JSON('{ "a" : 1 } '::bytea FORMAT JSON ENCODING UTF8);
+ json
+--------------
+ { "a" : 1 }
+(1 row)
+
+SELECT pg_typeof(JSON('{ "a" : 1 } '));
+ pg_typeof
+-----------
+ json
+(1 row)
+
+SELECT JSON(' 1 '::json);
+ json
+---------
+ 1
+(1 row)
+
+SELECT JSON(' 1 '::jsonb);
+ json
+------
+ 1
+(1 row)
+
+SELECT JSON(' 1 '::json WITH UNIQUE KEYS);
+ERROR: cannot use non-string types with WITH UNIQUE KEYS clause
+LINE 1: SELECT JSON(' 1 '::json WITH UNIQUE KEYS);
+ ^
+SELECT JSON(123);
+ERROR: cannot cast type integer to json
+LINE 1: SELECT JSON(123);
+ ^
+SELECT JSON('{"a": 1, "a": 2}');
+ json
+------------------
+ {"a": 1, "a": 2}
+(1 row)
+
+SELECT JSON('{"a": 1, "a": 2}' WITH UNIQUE KEYS);
+ERROR: duplicate JSON object key value
+SELECT JSON('{"a": 1, "a": 2}' WITHOUT UNIQUE KEYS);
+ json
+------------------
+ {"a": 1, "a": 2}
+(1 row)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON('123');
+ QUERY PLAN
+-----------------------------
+ Result
+ Output: JSON('123'::json)
+(2 rows)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON('123' FORMAT JSON);
+ QUERY PLAN
+-----------------------------
+ Result
+ Output: JSON('123'::json)
+(2 rows)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON('123'::bytea FORMAT JSON);
+ QUERY PLAN
+-----------------------------------------------
+ Result
+ Output: JSON('\x313233'::bytea FORMAT JSON)
+(2 rows)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON('123'::bytea FORMAT JSON ENCODING UTF8);
+ QUERY PLAN
+-------------------------------------------------------------
+ Result
+ Output: JSON('\x313233'::bytea FORMAT JSON ENCODING UTF8)
+(2 rows)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON('123' WITH UNIQUE KEYS);
+ QUERY PLAN
+----------------------------------------------
+ Result
+ Output: JSON('123'::text WITH UNIQUE KEYS)
+(2 rows)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON('123' WITHOUT UNIQUE KEYS);
+ QUERY PLAN
+-----------------------------
+ Result
+ Output: JSON('123'::json)
+(2 rows)
+
+-- JSON_SCALAR()
+SELECT JSON_SCALAR();
+ERROR: syntax error at or near ")"
+LINE 1: SELECT JSON_SCALAR();
+ ^
+SELECT JSON_SCALAR(NULL);
+ json_scalar
+-------------
+
+(1 row)
+
+SELECT JSON_SCALAR(NULL::int);
+ json_scalar
+-------------
+
+(1 row)
+
+SELECT JSON_SCALAR(123);
+ json_scalar
+-------------
+ 123
+(1 row)
+
+SELECT JSON_SCALAR(123.45);
+ json_scalar
+-------------
+ 123.45
+(1 row)
+
+SELECT JSON_SCALAR(123.45::numeric);
+ json_scalar
+-------------
+ 123.45
+(1 row)
+
+SELECT JSON_SCALAR(true);
+ json_scalar
+-------------
+ true
+(1 row)
+
+SELECT JSON_SCALAR(false);
+ json_scalar
+-------------
+ false
+(1 row)
+
+SELECT JSON_SCALAR(' 123.45');
+ json_scalar
+-------------
+ " 123.45"
+(1 row)
+
+SELECT JSON_SCALAR('2020-06-07'::date);
+ json_scalar
+--------------
+ "2020-06-07"
+(1 row)
+
+SELECT JSON_SCALAR('2020-06-07 01:02:03'::timestamp);
+ json_scalar
+-----------------------
+ "2020-06-07T01:02:03"
+(1 row)
+
+SELECT JSON_SCALAR('{}'::json);
+ json_scalar
+-------------
+ {}
+(1 row)
+
+SELECT JSON_SCALAR('{}'::jsonb);
+ json_scalar
+-------------
+ {}
+(1 row)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON_SCALAR(123);
+ QUERY PLAN
+----------------------------
+ Result
+ Output: JSON_SCALAR(123)
+(2 rows)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON_SCALAR('123');
+ QUERY PLAN
+------------------------------------
+ Result
+ Output: JSON_SCALAR('123'::text)
+(2 rows)
+
+-- JSON_SERIALIZE()
+SELECT JSON_SERIALIZE();
+ERROR: syntax error at or near ")"
+LINE 1: SELECT JSON_SERIALIZE();
+ ^
+SELECT JSON_SERIALIZE(NULL);
+ json_serialize
+----------------
+
+(1 row)
+
+SELECT JSON_SERIALIZE(JSON('{ "a" : 1 } '));
+ json_serialize
+----------------
+ { "a" : 1 }
+(1 row)
+
+SELECT JSON_SERIALIZE('{ "a" : 1 } ');
+ json_serialize
+----------------
+ { "a" : 1 }
+(1 row)
+
+SELECT JSON_SERIALIZE('1');
+ json_serialize
+----------------
+ 1
+(1 row)
+
+SELECT JSON_SERIALIZE('1' FORMAT JSON);
+ json_serialize
+----------------
+ 1
+(1 row)
+
+SELECT JSON_SERIALIZE('{ "a" : 1 } ' RETURNING bytea);
+ json_serialize
+----------------------------
+ \x7b20226122203a2031207d20
+(1 row)
+
+SELECT pg_typeof(JSON_SERIALIZE(NULL));
+ pg_typeof
+-----------
+ text
+(1 row)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON_SERIALIZE('{}');
+ QUERY PLAN
+-----------------------------------------------------
+ Result
+ Output: JSON_SERIALIZE('{}'::json RETURNING text)
+(2 rows)
+
+EXPLAIN (VERBOSE, COSTS OFF) SELECT JSON_SERIALIZE('{}' RETURNING bytea);
+ QUERY PLAN
+------------------------------------------------------
+ Result
+ Output: JSON_SERIALIZE('{}'::json RETURNING bytea)
+(2 rows)
+
期望 PostgreSQL 增加什么功能?
PolarDB for PostgreSQL云原生分布式开源数据库
PostgreSQL 解决方案集合
德哥 / digoal's github - 公益是一辈子的事.
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