Horton

Re: remaining sql/json patches

amit <amitlangote09@gmail.com>

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From: Amit Langote <amitlangote09@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Andrew Dunstan <andrew@dunslane.net>, jian he <jian.universality@gmail.com>, Erik Rijkers <er@xs4all.nl>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2023-11-16T08:48:55Z
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.

On Thu, Nov 16, 2023 at 2:11 AM Andres Freund <andres@anarazel.de> wrote:
> On 2023-11-15 22:00:41 +0900, Amit Langote wrote:
> > > This causes a nontrivial increase in the size of the parser (~5% in an
> > > optimized build here), I wonder if we can do better.
> >
> > Hmm, sorry if I sound ignorant but what do you mean by the parser here?
>
> gram.o, in an optimized build.
>
> > I can see that the byte-size of gram.o increases by 1.66% after the
> > above additions  (1.72% with previous versions).
>
> I'm not sure anymore how I measured it, but if you just looked at the total
> file size, that might not show the full gain, because of debug symbols
> etc. You can use the size command to look at just the code and data size.

$ size /tmp/gram.*
   text    data     bss     dec     hex filename
 661808       0       0  661808   a1930 /tmp/gram.o.unpatched
 672800       0       0  672800   a4420 /tmp/gram.o.patched

That's still a 1.66% increase in the code size:

(672800 - 661808) / 661808 % = 1.66

As for gram.c, the increase is a bit larger:

$ ll /tmp/gram.*
-rw-rw-r--. 1 amit amit 2605925 Nov 16 16:18 /tmp/gram.c.unpatched
-rw-rw-r--. 1 amit amit 2709422 Nov 16 16:22 /tmp/gram.c.patched

(2709422 - 2605925) / 2605925 % = 3.97

> > I've also checked
> > using log_parser_stats that there isn't much slowdown in the
> > raw-parsing speed.
>
> What does "isn't much slowdown" mean in numbers?

Sure, the benchmark I used measured the elapsed time (using
log_parser_stats) of parsing a simple select statement (*) averaged
over 10000 repetitions of the same query performed with `psql -c`:

Unpatched: 0.000061 seconds
Patched: 0.000061 seconds

Here's a look at the perf:

Unpatched:
   0.59%  [.] AllocSetAlloc
   0.51%  [.] hash_search_with_hash_value
   0.47%  [.] base_yyparse

Patched:
   0.63%  [.] AllocSetAlloc
   0.52%  [.] hash_search_with_hash_value
   0.44%  [.] base_yyparse

(*) select 1, 2, 3 from foo where a = 1

Is there a more relevant benchmark I could use?

-- 
Thanks, Amit Langote
EDB: http://www.enterprisedb.com