Horton

Re: Virtual generated columns

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: jian he <jian.universality@gmail.com>, Richard Guo <guofenglinux@gmail.com>
Cc: Zhang Mingli <zmlpostgres@gmail.com>, Dean Rasheed <dean.a.rasheed@gmail.com>, Alexander Lakhin <exclusion@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2025-02-14T10:59:48Z
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__.

On 13.02.25 14:06, jian he wrote:
> I didn't solve the out join semantic issue.
> i am wondering, can we do the virtual generated column expansion in
> the rewrite stage as is,
> and wrap the expressions in PHVs if the virtual generated
> columns come from the nullable side of an outer join.

PlaceHolderVar looks like a fitting mechanism for this.  But it's so far 
a planner node, so it might take some additional consideration if we 
want to expand where it's used.

Maybe a short-term fix would be to error out if we find ourselves about 
to expand a Var with varnullingrels != NULL.  That would mean you 
couldn't use a virtual generated column on the nullable output side of 
an outer join, which is annoying but not fatal, and we could fix it 
incrementally later.