Re: Virtual generated columns

Peter Eisentraut <peter@eisentraut.org>

From: Peter Eisentraut <peter@eisentraut.org>
To: pgsql-hackers <pgsql-hackers@postgresql.org>
Cc: jian he <jian.universality@gmail.com>, Dean Rasheed <dean.a.rasheed@gmail.com>
Date: 2025-01-08T16:14:30Z
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. Expand virtual generated columns for ALTER COLUMN TYPE

  2. Eliminate code duplication in replace_rte_variables callbacks

  3. Expand virtual generated columns in the planner

  4. Virtual generated columns

  5. Additional tests for stored generated columns

  6. Improve generated_stored test

  7. Fix handling of CREATE DOMAIN with GENERATED constraint syntax

  8. Add pg_constraint rows for not-null constraints

  9. Put generated_stored test objects in a schema

  10. Rename regress test generated to generated_stored

  11. Small code simplification

  12. Remove useless code

  13. Remove useless initializations

  14. doc: Clarify that pg_attrdef also stores generation expressions

  15. Clean out column-level pg_init_privs entries when dropping tables.

  16. Re-implement the ereport() macro using __VA_ARGS__.

Attachments

Here is a new patch version where I have gathered various pieces of 
feedback and improvement suggestions that are scattered over this 
thread.  I hope I got them all.  I will respond to the respective 
messages directly to give my response to each item.

One thing I could use some review on is the access control handling and 
security in general.  You can create virtual generated columns that have 
their own access privileges but which can read columns that the user 
does not have access to.  Kind of like a view.  This all appears to work 
correctly, but maybe someone wants to poke a hole into it.

Here is an example:

create user foo;
create user bar;
grant create on schema public to foo;
\c - foo
create table t1 (id int, ccnum text, ccredacted text generated always as 
(repeat('*', 12) || substr(ccnum, 13, 4)) virtual);
grant select (id, ccredacted) on table t1 to bar;
insert into t1 values (1, '1234567890123456');
\c - bar
select * from t1;  -- permission denied
select id, ccredacted from t1;  -- ok