Re: remaining sql/json patches

jian he <jian.universality@gmail.com>

From: jian he <jian.universality@gmail.com>

To: Amit Langote <amitlangote09@gmail.com>

Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, Himanshu Upadhyaya <upadhyaya.himanshu@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Erik Rijkers <er@xs4all.nl>, Andres Freund <andres@anarazel.de>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2024-03-29T09:59:11Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

SQL/JSON: Various improvements to SQL/JSON query function docs
- ce416fadb4b6 17.0 landed
- 42de72fa7b80 18.0 landed
SQL/JSON: Fix some obsolete comments.
- 290a6d800d90 17.0 landed
- 7768b6569de9 16.4 landed
- 3a8a1f3254b2 18.0 landed
SQL/JSON: Fix issues with DEFAULT .. ON ERROR / EMPTY
- c0fc0751862d 17.0 landed
JSON_TABLE: Add support for NESTED paths and columns
- bb766cde63b4 17.0 landed
Fix JsonExpr deparsing to emit QUOTES and WRAPPER correctly
- f6a2529920cf 17.0 landed
Fix typo introduced in 6185c9737
- 2f6e78b0619a 17.0 landed
Add basic JSON_TABLE() functionality
- de3600452b61 17.0 landed
Avoid splitting errmsg string to span multiple lines
- 085e759e9da7 17.0 landed
Add SQL/JSON query functions
- 6185c9737cf4 17.0 landed
Implement various jsonpath methods
- 66ea94e8e606 17.0 cited
Add soft error handling to some expression nodes
- aaaf9449ec6b 17.0 landed
- 7fbc75b26ed8 17.0 landed
Adjust populate_record_field() to handle errors softly
- 1edb3b491bee 17.0 landed
Refactor code used by jsonpath executor to fetch variables
- faa2b953ba3b 17.0 landed
Test EXPLAIN (FORMAT JSON) ... XMLTABLE
- 752533d40fd5 17.0 landed
Simplify productions for FORMAT JSON [ ENCODING name ]
- d3fe6e90bab5 17.0 landed
Add trailing commas to enum definitions
- 611806cd726f 17.0 cited
doc: add missing <returnvalue> and whitespace
- e055b6be7ebb 17.0 landed
Add more SQL/JSON constructor functions
- 03734a7fed7d 17.0 landed
Rename a nonterminal used in SQL/JSON grammar
- 254ac5a7c31f 17.0 landed
Some refactoring to export json(b) conversion functions
- b22391a2ff7b 17.0 landed
Don't include CaseTestExpr in JsonValueExpr.formatted_expr
- 66a9003e2e3e 16.0 landed
- b6e1157e7d33 17.0 landed
Code review for commit b6e1157e7d
- 7c7412cae3ea 17.0 landed
Pass constructName to transformJsonValueExpr()
- 7825a1b01e40 16.0 landed
- 785480c9533d 17.0 landed
Unify JSON categorize type API and export for external use
- 3c152a27b063 17.0 landed
Make some indentation in gram.y consistent
- 5edf438eeb00 17.0 landed
- 01f1f789df56 16.0 landed
Allow most keywords to be used as column labels without requiring AS.
- 06a7c3154f5b 14.0 cited
Reduce size of backend scanner's tables.
- 7f380c59f800 13.0 cited
Use perfect hashing, instead of binary search, for keyword lookup.
- c64d0cd5ce24 12.0 cited

On Fri, Mar 29, 2024 at 11:20 AM jian he <jian.universality@gmail.com> wrote:
>
>
> +<synopsis>
> +JSON_TABLE (
> +    <replaceable>context_item</replaceable>,
> <replaceable>path_expression</replaceable> <optional> AS
> <replaceable>json_path_name</replaceable> </optional> <optional>
> PASSING { <replaceable>value</replaceable> AS
> <replaceable>varname</replaceable> } <optional>, ...</optional>
> </optional>
> +    COLUMNS ( <replaceable
> class="parameter">json_table_column</replaceable> <optional>,
> ...</optional> )
> +    <optional> { <literal>ERROR</literal> | <literal>EMPTY</literal>
> } <literal>ON ERROR</literal> </optional>
> +)
> top level (not in the COLUMN clause) also allows
> <literal>NULL</literal> <literal>ON ERROR</literal>.
>
we can also specify <literal>DEFAULT expression</literal> <literal>ON
ERROR</literal>.
like:
SELECT * FROM JSON_TABLE(jsonb'"1.23"', 'strict $.a' COLUMNS (js2 int
PATH '$') default '1' on error);

+   <varlistentry>
+    <term>
+     <replaceable>name</replaceable> <replaceable>type</replaceable>
<literal>FORMAT JSON</literal> <optional>ENCODING
<literal>UTF8</literal></optional>
+          <optional> <literal>PATH</literal>
<replaceable>json_path_specification</replaceable> </optional>
+    </term>
+    <listitem>
+    <para>
+     Inserts a composite SQL/JSON item into the output row.
+    </para>
+    <para>
+     The provided <literal>PATH</literal> expression is evaluated and
+     the column is filled with the produced SQL/JSON item.  If the
+     <literal>PATH</literal> expression is omitted, path expression
+     <literal>$.<replaceable>name</replaceable></literal> is used,
+     where <replaceable>name</replaceable> is the provided column name.
+     In this case, the column name must correspond to one of the
+     keys within the SQL/JSON item produced by the row pattern.
+    </para>
+    <para>
+     Optionally, you can specify <literal>WRAPPER</literal>,
+     <literal>QUOTES</literal> clauses to format the output and
+     <literal>ON EMPTY</literal> and <literal>ON ERROR</literal> to handle
+     those scenarios appropriately.
+    </para>

Similarly, I am not sure of the description of "composite SQL/JSON item".
by observing the following 3 examples:
SELECT * FROM JSON_TABLE(jsonb'{"a": "z"}', '$.a' COLUMNS (js2 text
format json PATH '$' omit quotes));
SELECT * FROM JSON_TABLE(jsonb'{"a": "z"}', '$.a' COLUMNS (js2 text
format json PATH '$'));
SELECT * FROM JSON_TABLE(jsonb'{"a": "z"}', '$.a' COLUMNS (js2 text PATH '$'));

i think, FORMAT JSON specification means that,
if your specified type is text or varchar related AND didn't specify
quotes behavior
then FORMAT JSON produced output can be casted to json data type.
so FORMAT JSON seems not related to array and records data type.

also the last para can be:
+    <para>
+     Optionally, you can specify <literal>WRAPPER</literal>,
+     <literal>QUOTES</literal> clauses to format the output and
+     <literal>ON EMPTY</literal> and <literal>ON ERROR</literal> to handle
+     those missing values and structural errors, respectively.
+    </para>


+ ereport(ERROR,
+ errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("only string constants are supported in JSON_TABLE"
+   " path specification"),
should be:

+ ereport(ERROR,
+ errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("only string constants are supported in JSON_TABLE path
specification"),


+   <varlistentry>
+    <term>
+     <literal>AS</literal> <replaceable>json_path_name</replaceable>
+    </term>
+    <listitem>
+
+    <para>
+     The optional <replaceable>json_path_name</replaceable> serves as an
+     identifier of the provided
<replaceable>json_path_specification</replaceable>.
+     The path name must be unique and distinct from the column names.
+     When using the <literal>PLAN</literal> clause, you must specify the names
+     for all the paths, including the row pattern. Each path name can appear in
+     the <literal>PLAN</literal> clause only once.
+    </para>
+    </listitem>
+   </varlistentry>
as of v46, we don't have PLAN clause.
also "must be unique and distinct from the column names." seems incorrect.
for example:
SELECT * FROM JSON_TABLE(jsonb'"1.23"', '$.a' as js2 COLUMNS (js2 int
PATH '$'));