Horton

Re: SQL/JSON features for v15

Nikita Glukhov <n.gluhov@postgrespro.ru>

View thread View on postgr.es
From: Nikita Glukhov <n.gluhov@postgrespro.ru>
To: Pavel Stehule <pavel.stehule@gmail.com>, Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>, "Jonathan S. Katz" <jkatz@postgresql.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Andrew Dunstan <andrew@dunslane.net>, Tom Lane <tgl@sss.pgh.pa.us>, Michael Paquier <michael@paquier.xyz>, John Naylor <john.naylor@enterprisedb.com>, Amit Langote <amitlangote09@gmail.com>
Date: 2022-08-23T18:16:24Z
Lists: pgsql-hackers 
On 23.08.2022 20:38, Pavel Stehule wrote:
> út 23. 8. 2022 v 19:27 odesílatel Andres Freund <andres@anarazel.de> 
> napsal:
>
>     Hi,
>
>     On 2022-08-23 18:06:22 +0200, Pavel Stehule wrote:
>     > The errors that should be handled are related to json structure
>     errors. I
>     > don't think so we have to handle all errors and all conversions.
>     >
>     > The JSON knows only three types - and these conversions can be
>     written
>     > specially for this case - or we can write json io routines to be
>     able to
>     > signal error
>     > without an exception.
>
>     I think that's not true unfortunately. You can specify return
>     types, and
>     composite types can be populated. Which essentially requires arbitrary
>     coercions.
>
>
> Please, can you send an example? Maybe we try to fix a feature that is 
> not required by standard.

- Returning arbitrary types in JSON_VALUE using I/O coercion
from JSON string (more precisely, text::arbitrary_type cast):

SELECT JSON_QUERY(jsonb '"1, 2"', '$' RETURNING point);
  json_query
------------
  (1,2)
(1 row)


- Returning composite and array types in JSON_QUERY, which is implemented
reusing the code of our json[b]_populate_record[set]():

SELECT JSON_QUERY(jsonb '[1, "2", null]', '$' RETURNING int[]);
  json_query
------------
  {1,2,NULL}
(1 row)

-- 
Nikita Glukhov
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company

Commits

  1. JSON_TABLE: Add support for NESTED paths and columns

  2. Add basic JSON_TABLE() functionality

  3. Add SQL/JSON query functions

  4. Add soft error handling to some expression nodes

  5. Adjust populate_record_field() to handle errors softly

  6. Refactor code used by jsonpath executor to fetch variables

  7. Add more SQL/JSON constructor functions

  8. SQL/JSON: support the IS JSON predicate

  9. SQL/JSON: add standard JSON constructor functions

  10. Revert SQL/JSON features

  11. Numeric error suppression in jsonpath