Re: misleading error message in ProcessUtilitySlow T_CreateStatsStmt

jian he <jian.universality@gmail.com>

From: jian he <jian.universality@gmail.com>

To: Tom Lane <tgl@sss.pgh.pa.us>

Cc: Álvaro Herrera <alvherre@kurilemu.de>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Kirill Reshke <reshkekirill@gmail.com>

Date: 2025-08-29T04:07:24Z

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 →

CREATE STATISTICS: improve misleading error message
- cbd3732cbbaa 14.20 landed
- 4529861cc408 15.15 landed
- f30c04682cdf 16.11 landed
- f9b41f3e1ecd 17.7 landed
- 38883916e41c 18.0 landed
- 9ec0b29976b6 19 (unreleased) landed
- f9a7622483c3 15.15 landed
- f225473cbae2 19 (unreleased) landed
- e9fb314c7ad8 17.7 landed
- d84a6c3dad1f 16.11 landed
- b830f9d67463 14.20 landed
- 3eea4dc2c7cf 18.0 landed
Glossary: improve definition of "relation"
- 16a9165ce4a4 19 (unreleased) landed
Extended statistics on expressions
- a4d75c86bf15 14.0 cited

Attachments

v2-0001-refactor-CreateStatsStmt.patch (text/x-patch) patch v2-0001

On Fri, Aug 29, 2025 at 5:46 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> =?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@kurilemu.de> writes:
> > I propose to use this report:
>
> > ERROR:  cannot create statistics on specified relation
> > DETAIL:  CREATE STATISTICS only supports tables, materialized views, foreign tables, and partitioned tables.
>
> WFM, although I think you could shorten it to "tables, materialized
> views, and foreign tables".  We generally expect that partitioned
> tables are included when saying "tables", no?  I'm not dead set on
> that either way, though.
>

https://www.postgresql.org/docs/current/sql-copy.html
use "COPY TO can be used only with plain tables, not views, and does
not copy rows from child tables or child partitions"

>
> Alternatively, maybe the right fix is to move the parse-analysis
> work into CreateStatistics altogether.  I think there is not a
> very good argument for ProcessUtilitySlow doing all that stuff.
> It's supposed to mainly just be a dispatching switch(), IMO.
>
seems doable.
transformStatsStmt, CreateStatistics both used only twice, refactoring arguments
should be fine.
please check the attached POC, regress tests also added.

main idea is
first check CreateStatsStmt->relations,
then call transformStatsStmt, transformStatsStmt only to transform
CreateStatsStmt->exprs.
also the above complaint about the relation lock issue will be resolved.