Horton

Re: pg18: Virtual generated columns are not (yet) safe when superuser selects from them

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: jian he <jian.universality@gmail.com>
Cc: Feike Steenbergen <feikesteenbergen@gmail.com>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
Date: 2025-06-24T09:42:46Z
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. Restrict virtual columns to use built-in functions and types

  2. Fix virtual generated column type checking for ALTER TABLE

  3. Expand virtual generated columns in the planner

On 23.06.25 18:11, jian he wrote:
> seems we didn't check the ALTER TABLE case.
> 
> CREATE TYPE double_int as (a int, b int);
> CREATE TABLE y (a int);
> alter table y add column b double_int GENERATED ALWAYS AS ((a * 2, a *
> 3)) VIRTUAL;
> 
> in ATExecAddColumn, we can change it to:
>      CheckAttributeType(NameStr(attribute->attname),
> attribute->atttypid, attribute->attcollation,
>                         list_make1_oid(rel->rd_rel->reltype),
>                         (attribute->attgenerated ==
> ATTRIBUTE_GENERATED_VIRTUAL ? CHKATYPE_IS_VIRTUAL : 0));

Yes, this is an existing fault separate from this patch.  I have pushed 
a fix for this along these lines.