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From: Nikita Glukhov <[email protected]>
To: Pavel Stehule <[email protected]>
To: PostgreSQL-development <[email protected]>
Cc: Erik Rijkers <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: Thomas Munro <[email protected]>
Cc: Andrew Alsup <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Dmitry Dolgov <[email protected]>
Cc: Oleg Bartunov <[email protected]>
Cc: Alexander Korotkov <[email protected]>
Cc: Michael Paquier <[email protected]>
Cc: Simon Riggs <[email protected]>
Cc: Andrew Dunstan <[email protected]>
Subject: Re: SQL/JSON: functions
Date: Fri, 20 Mar 2020 01:57:21 +0300
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAFj8pRB=hPYBBsYE9nqqOnd+zHGJXXzvjw4w+KeX0UXYTdWHDg@mail.gmail.com>
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Attached 45th version of the patches.

Nodes JsonFormat, JsonReturning, JsonPassing, JsonBehavior were fixed.

On 17.03.2020 21:35, Pavel Stehule wrote:
>
> út 17. 3. 2020 v 1:55 odesílatel Nikita Glukhov 
> <[email protected] <mailto:[email protected]>> napsal:
>
>     Attached 44th version of the patches.
>
>
>     On 12.03.2020 16:41, Pavel Stehule wrote:
>>
>>     On 12.03.2020 00:09 Nikita Glukhov wrote:
>>
>>         Attached 43rd version of the patches.
>>
>>         The previous patch #4 ("Add function formats") was removed.
>>         Instead, introduced new executor node JsonCtorExpr which is used to wrap
>>         SQL/JSON constructor function calls (FuncExpr, Aggref, WindowFunc).
>>
>>         Also, JsonIsPredicate node began to be used as executor node.
>>         This helped to remove unnecessary json[b]_is_valid() user functions.
>>
>>
>>     It looks very well - all tests passed, code looks well.
>>
>>     Now, when there are special nodes, then the introduction of
>>     COERCE_INTERNAL_CAST is not necessary, and it is only my one and
>>     last objection again this patch's set.
>>
>     I have removed patch #3 with COERCE_INTERNAL_CAST too.
>
>     Coercions in JsonValueExpr in JsonCtorExpr, which were previously hidden with
>     COERCE_INTERNAL_CAST and which were outputted as RETURNING or FORMAT JSON
>     clauses, now moved into separate expressions.
>
> I am looking on the code, and although the code is correct it doesn't 
> look well (consistently with other node types).
>
> I think so JsonFormat and JsonReturning should be node types, not just 
> structs. If these types will be nodes, then you can simplify 
> _readJsonExpr and all node operations on this node.

JsonFormat and JsonReturning was transformed into nodes, and not included
directly into other nodes now.


>     User functions json[b]_build_object_ext() and json[b]_build_array_ext() also
>     can be easily removed.   But it seems harder to remove new aggregate functions
>     json[b]_objectagg() and json[b]_agg_strict(), because they can't be called
>     directly from JsonCtorExpr node.
>
>
> I don't see reasons for another reduction now. Can be great if you can 
> finalize work what you plan for pg13.
>

> +<->READ_ENUM_FIELD(on_error.btype, JsonBehaviorType);
> +<->READ_NODE_FIELD(on_error.default_expr);
> +<->READ_ENUM_FIELD(on_empty.btype, JsonBehaviorType);
> +<->READ_NODE_FIELD(on_empty.default_expr);
>
> JsonBehavior is node type. Then why you don't write just
>
> READ_NODE_FIELD(on_error);
> READ_NODE_FIELD(on_empty)
>
> ??

JsonBehavior now used in JsonExpr as a pointer to node.


> And maybe the code can be better if you don't use JsonPassing struct 
> (or use it only inside gram.y) and pass just List *names, List *values.
>
> Nodes should to contains another nodes or scalar types. Using structs 
> (that are not nodes)  inside doesn't look consistently.
>
JsonPassing was replaced with two Lists.


> I found some not finished code in 0003 patch
> +
> +json_name_and_value:
> +/* TODO
> +<-><--><-->KEY c_expr VALUE_P json_value_expr %prec POSTFIXOP
> +<-><--><--><-->{ $$ = makeJsonKeyValue($2, $4); }
> +<-><--><-->|
> +*/
>
This is unsupported variant of standard syntax, because it seems to lead
to unresolvable conflicts.  The only supports syntax is:

JSON_OBJECT(key : value)
JSON_OBJECT(key VALUE value)

>
>     The support for json type in jsonpath also seems to be immature, so I will try
>     to remove it in the next iteration.
>
> What do you think? This patch is little bit off topic, so if you don't 
> need it, then can be removed. Is there some dependency for "jsontable" ?

There is a dependency in SQL/JSON query functions executor, because executor
uses new structure JsonItem instead of plain JsonbValue.  I will try to
preserve refactoring with JsonItem introduction, but remove json support.
If it will be still unacceptable, I will try to completely remove patch #1.

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



Attachments:

  [application/gzip] 0001-Jsonpath-support-for-json-v45.patch.gz (43.6K, ../[email protected]/3-0001-Jsonpath-support-for-json-v45.patch.gz)
  download

  [application/gzip] 0002-Add-common-SQL-JSON-clauses-v45.patch.gz (8.0K, ../[email protected]/4-0002-Add-common-SQL-JSON-clauses-v45.patch.gz)
  download

  [application/gzip] 0003-SQL-JSON-constructors-v45.patch.gz (30.4K, ../[email protected]/5-0003-SQL-JSON-constructors-v45.patch.gz)
  download

  [application/gzip] 0004-SQL-JSON-IS-JSON-predicate-v45.patch.gz (12.6K, ../[email protected]/6-0004-SQL-JSON-IS-JSON-predicate-v45.patch.gz)
  download

  [application/gzip] 0005-SQL-JSON-query-functions-v45.patch.gz (39.4K, ../[email protected]/7-0005-SQL-JSON-query-functions-v45.patch.gz)
  download

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