Re: Extended Statistics set/restore/clear functions. - Mailing list pgsql-hackers

From jian he
Subject Re: Extended Statistics set/restore/clear functions.
Date
Msg-id CACJufxHVKiVEvCsc11oxOM=0GgjqChFwi-ii4RJuw95ZFB_fHQ@mail.gmail.com
Whole thread Raw
In response to Re: Extended Statistics set/restore/clear functions.  (Corey Huinker <corey.huinker@gmail.com>)
List pgsql-hackers
On Tue, Nov 18, 2025 at 4:52 PM Corey Huinker <corey.huinker@gmail.com> wrote:
> v15:
>
> - catches duplicate object keys cited above
> - enforces attnum ordering (ascending positive numbers followed by descending negative numbers, no zeros allowed),
whichmeans we get duplicate attnum detection for free 
> - attnum validation is now done as soon as the attnum is parsed
> - tests refactored to put attnums in proper order
> - unfortunately, this means that one of the error cases from stats_import.sql (attnum = 0) is now an error rather
thansomething that can be soft-excluded. 
> - didn't enforce combinatorical completeness for dependencies because not all combinations are guaranteed to be
there.
> - didn't enforce combinatorical completeness for ndistinct because I'm not convinced we should.
>

hi.

some of the switch->default, default don't have ``break``.

+ for (int i = 0; i < nitems; i++)
+ {
+ MVNDistinctItem *item = parse_state.distinct_items->elements[i].ptr_value;

exposing the ptr_value seems not a good idea, we can foreach_ptr
the attached patch using foreach_ptr.

in function pg_ndistinct_in some errsave can change to ereturn.
(I didn't do this part, though).

+ /*
+ * The attnum cannot be zero a negative number beyond the number of the
+ * possible expressions.
+ */
+ if (attnum == 0 || attnum < (0-STATS_MAX_DIMENSIONS))
+ {
+ errsave(parse->escontext,
+ errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
+ errmsg("malformed pg_ndistinct: \"%s\"", parse->str),
+ errdetail("Invalid \"%s\" element: %d.",
+ PG_NDISTINCT_KEY_ATTRIBUTES, attnum));
+ return JSON_SEM_ACTION_FAILED;
+ }
This part had no coverage tests, so I added a few.


as mentioned before
+ errsave(parse->escontext,
+ errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),
+ errmsg("malformed pg_ndistinct: \"%s\"", parse->str),
+ errdetail("The \"%s\" key must contain an array of at least %d "
+  "and no more than %d attributes.",
+  PG_NDISTINCT_KEY_NDISTINCT, 2, STATS_MAX_DIMENSIONS));
here PG_NDISTINCT_KEY_NDISTINCT, should be PG_NDISTINCT_KEY_ATTRIBUTES.


Please check the attached minor miscellaneous changes.

--
jian
https://www.enterprisedb.com/

Attachment

pgsql-hackers by date:

Previous
From: Nazir Bilal Yavuz
Date:
Subject: Re: Trying out read streams in pgvector (an extension)
Next
From: Jim Jones
Date:
Subject: Re: [PATCH] Add pg_get_tablespace_ddl() function to reconstruct CREATE TABLESPACE statement