Horton

Re: remaining sql/json patches

jian he <jian.universality@gmail.com>

View thread
From: jian he <jian.universality@gmail.com>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Himanshu Upadhyaya <upadhyaya.himanshu@gmail.com>, Erik Rijkers <er@xs4all.nl>, Andres Freund <andres@anarazel.de>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-04-02T06:54:13Z
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

hi.

+/*
+ * Recursively transform child JSON_TABLE plan.
+ *
+ * Default plan is transformed into a cross/union join of its nested columns.
+ * Simple and outer/inner plans are transformed into a JsonTablePlan by
+ * finding and transforming corresponding nested column.
+ * Sibling plans are recursively transformed into a JsonTableSibling.
+ */
+static Node *
+transformJsonTableChildPlan(JsonTableParseContext *cxt,
+ List *columns)
this comment is not the same as the function intention for now.
maybe we need to refactor it.


/*
* Each call to fetch a new set of rows - of which there may be very many
* if XMLTABLE is being used in a lateral join - will allocate a possibly
* substantial amount of memory, so we cannot use the per-query context
* here. perTableCxt now serves the same function as "argcontext" does in
* FunctionScan - a place to store per-one-call (i.e. one result table)
* lifetime data (as opposed to per-query or per-result-tuple).
*/
MemoryContextSwitchTo(tstate->perTableCxt);

maybe we can replace "XMLTABLE" to "XMLTABLE or JSON_TABLE"?



/* Transform and coerce the PASSING arguments to to jsonb. */
there should be only one "to"?

-----------------------------------------------------------------------------------------------------------------------
json_table_column clause doesn't have a passing clause.
we can only have one passing clause in json_table.
but during JsonTableInitPathScan, for each output columns associated
JsonTablePlanState
we already initialized the PASSING arguments via  `planstate->args = args;`
also transformJsonTableColumn already has a passingArgs argument.
technically we can use the jsonpath variable for every output column
regardless of whether it's nested or not.

JsonTable already has the "passing" clause,
we just need to pass it to function transformJsonTableColumns and it's callees.
based on that, I implemented it. seems quite straightforward.
I also wrote several contrived, slightly complicated tests.
It seems to work just fine.

simple explanation:
previously the following sql will fail, error message is that "could
not find jsonpath variable  %s".
now it will work.

SELECT sub.* FROM
JSON_TABLE(jsonb '{"a":{"za":[{"z1": [11,2222]},{"z21": [22,
234,2345]}]},"c": 3}',
'$' PASSING 22 AS x, 234 AS y
COLUMNS(
xx int path '$.c',
NESTED PATH '$.a.za[1]' as n1 columns
(NESTED PATH '$.z21[*]' as n2
COLUMNS (z21 int path '$?(@ == $"x" || @ == $"y" )' default 0 on empty)),
NESTED PATH '$.a.za[0]' as n4 columns
(NESTED PATH '$.z1[*]' as n3
COLUMNS (z1 int path '$?(@ > $"y" + 1988)' default 0 on empty)))
)sub;