Re: Virtual generated columns

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

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

To: Peter Eisentraut <peter@eisentraut.org>

Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, jian he <jian.universality@gmail.com>

Date: 2025-01-15T14:12:52Z

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

virt-gen-cols-with-returning-old-new.patch.no-cfbot (application/octet-stream)

On Tue, 14 Jan 2025 at 13:37, Peter Eisentraut <peter@eisentraut.org> wrote:
>
> Here is a new patch with that fixed and also a few
> tweaks suggested by Jian.
>

I'm hoping to push my RETURNING OLD/NEW patch [1] soon, so I thought
that I would check how it works together with this patch. The good
news is that AFAICS everything just works, and it's possible to return
old/new virtual generated columns in DML queries as expected.

It did require a minor update, because my patch adds a new
"result_relation" argument to ReplaceVarsFromTargetList() -- needed in
DML queries because, when propagating a Var's old/new
varreturningtype, replacement Vars need to be handled differently
depending on whether or not they refer to the result relation. So that
affects expand_generated_columns_internal(), when called from
fireRIRrules(). OTOH, from expand_generated_columns_in_expr() it's OK
to just pass 0 as the result relation index, because there won't be
any old/new Vars in an expression that's not part of a DML query.

Attached is the delta patch I used to handle this, along with a couple
of simple test cases. It doesn't really matter which feature makes it
in first, but the one that comes second will need to do something like
this.

Regards,
Dean

[1] https://commitfest.postgresql.org/51/4723/