Re: Virtual generated columns

Dean Rasheed <dean.a.rasheed@gmail.com>

From: Dean Rasheed <dean.a.rasheed@gmail.com>

To: Richard Guo <guofenglinux@gmail.com>

Cc: Peter Eisentraut <peter@eisentraut.org>, jian he <jian.universality@gmail.com>, Zhang Mingli <zmlpostgres@gmail.com>, Alexander Lakhin <exclusion@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2025-02-19T15:25:05Z

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 →

Expand virtual generated columns for ALTER COLUMN TYPE
- 5069fef1cfae 18.0 landed
Eliminate code duplication in replace_rte_variables callbacks
- 363a6e8c6fcf 18.0 landed
Expand virtual generated columns in the planner
- 1e4351af329f 18.0 landed
Virtual generated columns
- 83ea6c54025b 18.0 landed
Additional tests for stored generated columns
- 41084409f635 18.0 landed
Improve generated_stored test
- 44b61efb7928 18.0 landed
- 86749ea3b766 18.0 landed
Fix handling of CREATE DOMAIN with GENERATED constraint syntax
- 84a67725cd11 18.0 landed
Add pg_constraint rows for not-null constraints
- 14e87ffa5c54 18.0 cited
Put generated_stored test objects in a schema
- 894be11adfa6 18.0 landed
Rename regress test generated to generated_stored
- b9ed4969250d 18.0 landed
Small code simplification
- 7ff9afbbd1df 18.0 landed
Remove useless code
- e26d313bad92 18.0 landed
Remove useless initializations
- da2aeba8f533 18.0 landed
doc: Clarify that pg_attrdef also stores generation expressions
- da486d360103 18.0 landed
Clean out column-level pg_init_privs entries when dropping tables.
- 76618097a6c0 17.0 cited
Re-implement the ereport() macro using __VA_ARGS__.
- e3a87b4991cc 13.0 cited

Attachments

v4-0001-Expand-virtual-generated-columns-in-the-planner.patch (text/x-patch) patch v4-0001

On Wed, 19 Feb 2025 at 01:42, Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>
> One thing I don't like about this is that it's introducing more code
> duplication between pullup_replace_vars() and
> ReplaceVarsFromTargetList(). Those already had a lot of code in common
> before RETURNING OLD/NEW was added, and this is duplicating even more
> code. I think it'd be better to refactor so that they share common
> code, since it has become quite complex, and it would be better to
> have just one place to maintain. Attached is an updated patch doing
> that.
>

I've been doing some more testing of this, and attached is another
update, improving a few comments and adding regression tests based on
the cases discussed so far here.

One of the new regression tests fails, which actually appears to be a
pre-existing grouping sets bug, due to the fact that only non-Vars are
wrapped in PHVs. This bug can be triggered without virtual generated
columns:

CREATE TABLE t (a int, b int);
INSERT INTO t VALUES (1, 1);

SELECT * FROM (SELECT a, a AS b FROM t) AS vt
GROUP BY GROUPING SETS (a, b)
HAVING b = 1;

 a | b
---+---
 1 |
(1 row)

whereas the result should be

 a | b
---+---
   |  1
(1 row)

For reference, this code dates back to 90947674fc.

Regards,
Dean