Horton

Re: remaining sql/json patches

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Erik Rijkers <er@xs4all.nl>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-01-03T10:50:26Z
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 →

  1. SQL/JSON: Various improvements to SQL/JSON query function docs

  2. SQL/JSON: Fix some obsolete comments.

  3. SQL/JSON: Fix issues with DEFAULT .. ON ERROR / EMPTY

  4. JSON_TABLE: Add support for NESTED paths and columns

  5. Fix JsonExpr deparsing to emit QUOTES and WRAPPER correctly

  6. Fix typo introduced in 6185c9737

  7. Add basic JSON_TABLE() functionality

  8. Avoid splitting errmsg string to span multiple lines

  9. Add SQL/JSON query functions

  10. Implement various jsonpath methods

  11. Add soft error handling to some expression nodes

  12. Adjust populate_record_field() to handle errors softly

  13. Refactor code used by jsonpath executor to fetch variables

  14. Test EXPLAIN (FORMAT JSON) ... XMLTABLE

  15. Simplify productions for FORMAT JSON [ ENCODING name ]

  16. Add trailing commas to enum definitions

  17. doc: add missing <returnvalue> and whitespace

  18. Add more SQL/JSON constructor functions

  19. Rename a nonterminal used in SQL/JSON grammar

  20. Some refactoring to export json(b) conversion functions

  21. Don't include CaseTestExpr in JsonValueExpr.formatted_expr

  22. Code review for commit b6e1157e7d

  23. Pass constructName to transformJsonValueExpr()

  24. Unify JSON categorize type API and export for external use

  25. Make some indentation in gram.y consistent

  26. Allow most keywords to be used as column labels without requiring AS.

  27. Reduce size of backend scanner's tables.

  28. Use perfect hashing, instead of binary search, for keyword lookup.

Attachments

On Fri, Dec 22, 2023 at 9:01 PM jian he <jian.universality@gmail.com> wrote:
>
> Hi
>
> + /* FALLTHROUGH */
> + case JTC_EXISTS:
> + case JTC_FORMATTED:
> + {
> + Node   *je;
> + CaseTestExpr *param = makeNode(CaseTestExpr);
> +
> + param->collation = InvalidOid;
> + param->typeId = cxt->contextItemTypid;
> + param->typeMod = -1;
> +
> + if (rawc->wrapper != JSW_NONE &&
> + rawc->quotes != JS_QUOTES_UNSPEC)
> + ereport(ERROR,
> + (errcode(ERRCODE_SYNTAX_ERROR),
> + errmsg("cannot use WITH WRAPPER clause for formatted colunmns"
> + " without also specifying OMIT/KEEP QUOTES"),
> + parser_errposition(pstate, rawc->location)));
>
> typo, should be "formatted columns".
> I suspect people will be confused with the meaning of "formatted column".
> maybe we can replace this part:"cannot use WITH WRAPPER clause for
> formatted column"
> to
> "SQL/JSON  WITH WRAPPER behavior must not be specified when FORMAT
> clause is used"
>
> SELECT * FROM JSON_TABLE(jsonb '"world"', '$' COLUMNS (item text
> FORMAT JSON PATH '$' with wrapper KEEP QUOTES));
> ERROR:  cannot use WITH WRAPPER clause for formatted colunmns without
> also specifying OMIT/KEEP QUOTES
> LINE 1: ...T * FROM JSON_TABLE(jsonb '"world"', '$' COLUMNS (item text ...
>                                                              ^
> this error is misleading, since now I am using WITH WRAPPER clause for
> formatted columns and specified KEEP QUOTES.
>

Hi. still based on v33.
JSON_TABLE:
I also refactor parse_jsontable.c error reporting, now the error
message will be consistent with json_query.
now you can specify wrapper freely as long as you don't specify
wrapper and quote at the same time.
overall, json_table behavior is more consistent with json_query and json_value.
I also added some tests.

+void
+ExecEvalJsonCoercion(ExprState *state, ExprEvalStep *op,
+ ExprContext *econtext)
+{
+ JsonCoercion *coercion = op->d.jsonexpr_coercion.coercion;
+ ErrorSaveContext *escontext = op->d.jsonexpr_coercion.escontext;
+ Datum res = *op->resvalue;
+ bool resnull = *op->resnull;
+
+ if (coercion->via_populate)
+ {
+ void *cache = op->d.jsonexpr_coercion.json_populate_type_cache;
+
+ *op->resvalue = json_populate_type(res, JSONBOID,
+   coercion->targettype,
+   coercion->targettypmod,
+   &cache,
+   econtext->ecxt_per_query_memory,
+   op->resnull, (Node *) escontext);
+ }
+ else if (coercion->via_io)
+ {
+ FmgrInfo   *input_finfo = op->d.jsonexpr_coercion.input_finfo;
+ Oid typioparam = op->d.jsonexpr_coercion.typioparam;
+ char   *val_string = resnull ? NULL :
+ JsonbUnquote(DatumGetJsonbP(res));
+
+ (void) InputFunctionCallSafe(input_finfo, val_string, typioparam,
+ coercion->targettypmod,
+ (Node *) escontext,
+ op->resvalue);
+ }
via_populate, via_io should be mutually exclusive.
your patch, in some cases, both (coercion->via_io) and
(coercion->via_populate) are true.
(we can use elog find out).
I refactor coerceJsonFuncExprOutput, so now it will be mutually exclusive.
I also add asserts to it.

By default, json_query keeps quotes, json_value omit quotes.
However, json_table will be transformed to json_value or json_query
based on certain criteria,
that means we need to explicitly set the JsonExpr->omit_quotes in the
function transformJsonFuncExpr
for case JSON_QUERY_OP and JSON_VALUE_OP.

We need to know the QUOTE behavior in the function ExecEvalJsonCoercion.
Because for ExecEvalJsonCoercion, the coercion datum source can be a
scalar string item,
scalar items means RETURNING clause is dependent on QUOTE behavior.
keep quotes, omit quotes the results are different.
consider
JSON_QUERY(jsonb'{"rec": "[1,2]"}', '$.rec' returning int4range omit quotes);
and
JSON_QUERY(jsonb'{"rec": "[1,2]"}', '$.rec' returning int4range omit quotes);

to make sure ExecEvalJsonCoercion can distinguish keep and omit quotes,
I added a bool keep_quotes to struct JsonCoercion.
(maybe there is a more simple way, so far, that's what I come up with).
the keep_quotes value will be settled in the function transformJsonFuncExpr.
After refactoring, in ExecEvalJsonCoercion, keep_quotes is true then
call JsonbToCString, else call JsonbUnquote.

example:
SELECT JSON_QUERY(jsonb'{"rec": "{1,2,3}"}', '$.rec' returning int[]
omit quotes);
without my changes, return NULL
with my changes:
 {1,2,3}

JSON_VALUE:
main changes:
--- a/src/test/regress/expected/jsonb_sqljson.out
+++ b/src/test/regress/expected/jsonb_sqljson.out
@@ -301,7 +301,11 @@ SELECT JSON_VALUE(jsonb '"2017-02-20"', '$'
RETURNING date) + 9;
 -- Test NULL checks execution in domain types
 CREATE DOMAIN sqljsonb_int_not_null AS int NOT NULL;
 SELECT JSON_VALUE(jsonb 'null', '$' RETURNING sqljsonb_int_not_null);
-ERROR:  domain sqljsonb_int_not_null does not allow null values
+ json_value
+------------
+
+(1 row)
+
I think the change is correct, given `SELECT JSON_VALUE(jsonb 'null',
'$' RETURNING int4range);` returns NULL.

I also attached a test.sql, without_patch.out (apply v33 only),
with_patch.out (my changes based on v33).
So you can see the difference after applying the patch, in case, my
wording is not clear.