MIME-Version: 1.0
References: <CADkLM=dpz3KFnqP-dgJ-zvRvtjsa8UZv8wDAQdqho=qN3kX0Zg@mail.gmail.com>
 <4630636f-7720-4ce4-ab1c-253b390e5174@vondra.me> <CADkLM=cWdTvyAEQcxw-6er3umo=R1ZKU_9jf2ZinNxRf9MbQZg@mail.gmail.com>
 <b4ba8ed9-f1b3-4b6b-8612-ff42d65c18c6@vondra.me> <CADkLM=dnknZtCgdp2CmRp8gjkau1axYQ7SBMgcj74KgvjQzOwQ@mail.gmail.com>
 <CACJufxEZYqocFdgn-x-bJMRBSk_zkS=ziGGkaSumteiPDksnsg@mail.gmail.com>
In-Reply-To: <CACJufxEZYqocFdgn-x-bJMRBSk_zkS=ziGGkaSumteiPDksnsg@mail.gmail.com>
From: jian he <jian.universality@gmail.com>
Date: Wed, 29 Jan 2025 15:50:09 +0800
Message-ID: <CACJufxF0hnpjdsjrx4zuktVMaFOqM=mx3xQXctn2262vmwCapg@mail.gmail.com>
Subject: Re: Extended Statistics set/restore/clear functions.
To: Corey Huinker <corey.huinker@gmail.com>
Cc: Tomas Vondra <tomas@vondra.me>, pgsql-hackers@lists.postgresql.org
Content-Type: text/plain; charset="UTF-8"
Archived-At: <https://www.postgresql.org/message-id/CACJufxF0hnpjdsjrx4zuktVMaFOqM%3Dmx3xQXctn2262vmwCapg%40mail.gmail.com>
Precedence: bulk

hi.

select '{"1, 0B100101":"NaN"}'::pg_ndistinct;
      pg_ndistinct
------------------------
 {"1, 37": -2147483648}
(1 row)

this is not what we expected?
For the VALUE part of pg_ndistinct, float8 has 3 special values: inf, -inf, NaN.

For the key part of pg_ndistinct, see example.
select '{"1, 16\t":"1"}'::pg_ndistinct;
here \t is not tab character, ascii 9. it's two characters: backslash
and character "t".
so here it should error out?
(apply this to \n, \r, \b)


pg_ndistinct_in(PG_FUNCTION_ARGS)
ending part should be:

    freeJsonLexContext(lex);
    if (result == JSON_SUCCESS)
    {
        ......
    }
    else
    {
       ereturn(parse_state.escontext, (Datum) 0,
                    errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
                    errmsg("malformed pg_ndistinct: \"%s\"", str),
                    errdetail("Must be valid JSON."));
       PG_RETURN_NULL();
    }
result should be either JSON_SUCCESS or anything else.


all these functions:
ndistinct_object_start, ndistinct_array_start,
ndistinct_object_field_start, ndistinct_array_element_start
have
ndistinctParseState *parse = state;

do we need to change it to
ndistinctParseState *parse = (ndistinctParseState *)state;
?


ndistinctParseState need to add to src/tools/pgindent/typedefs.list
probably change it to "typedef struct ndistinctParseState".
also struct ndistinctParseState need placed in the top of
src/backend/statistics/mvdistinct.c
not in line 340?