Horton

Re: remaining sql/json patches

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Erik Rijkers <er@xs4all.nl>, jian he <jian.universality@gmail.com>, Andrew Dunstan <andrew@dunslane.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-01-18T17:11:18Z
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 2024-Jan-18, Alvaro Herrera wrote:

> commands/explain.c (Hmm, I think this is a preexisting bug actually)
> 
>     3893          18 :         case T_TableFuncScan:
>     3894          18 :             Assert(rte->rtekind == RTE_TABLEFUNC);
>     3895          18 :             if (rte->tablefunc)
>     3896           0 :                 if (rte->tablefunc->functype == TFT_XMLTABLE)
>     3897           0 :                     objectname = "xmltable";
>     3898             :                 else            /* Must be TFT_JSON_TABLE */
>     3899           0 :                     objectname = "json_table";
>     3900             :             else
>     3901          18 :                 objectname = NULL;
>     3902          18 :             objecttag = "Table Function Name";
>     3903          18 :             break;

Indeed -- the problem seems to be that add_rte_to_flat_rtable is
creating a new RTE and zaps the ->tablefunc pointer for it.  So when
EXPLAIN goes to examine the struct, there's a NULL pointer there and
nothing is printed.

One simple fix is to change add_rte_to_flat_rtable so that it doesn't
zero out the tablefunc pointer, but this is straight against what that
function is trying to do, namely to remove substructure.  Which means
that we need to preserve the name somewhere else.  I added a new member
to RangeTblEntry for this, which perhaps is a little ugly.  So here's
the patch for that.  (I also added an alias to one XMLTABLE invocation
under EXPLAIN, to show what it looks like when an alias is specified.
Otherwise they're always shown as "XMLTABLE" "xmltable" which is a bit
dumb).

Another possible way out is to decide that we don't want the
"objectname" to be reported here.  I admit it's perhaps redundant.  In
this case we'd just remove lines 3896-3899 shown above and let it be
NULL.

Thoughts?

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/