Horton

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

Christoph Berg <myon@debian.org>

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From: Christoph Berg <myon@debian.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Feike Steenbergen <feikesteenbergen@gmail.com>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
Date: 2025-06-05T16:03:51Z
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

Re: Tom Lane
> > Extending the idea, perhaps the check could be moved to run-time and
> > recursively check that only immutable functions are called, including
> > user-defined immutable functions?
> 
> I don't think I'd trust that.  UDFs can claim to be immutable but
> be lying about it.

That's why I said "recursively". Then truly immutable user-defined
functions could still be used.

But practically, people will probably want to select from other tables
anyway (I've already had to tell a customer that virtual columns do
not allow that), so the use-case for user immutable functions is
probably very thin.

Christoph