Re: Virtual generated columns

Vik Fearing <vik@postgresfriends.org>

From: Vik Fearing <vik@postgresfriends.org>

To: Marcos Pegoraro <marcos@f10.com.br>, Peter Eisentraut <peter@eisentraut.org>

Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, jian he <jian.universality@gmail.com>, Dean Rasheed <dean.a.rasheed@gmail.com>

Date: 2025-01-08T19:23:35Z

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

On 08/01/2025 20:19, Marcos Pegoraro wrote:
> Em qua., 8 de jan. de 2025 às 13:14, Peter Eisentraut 
> <peter@eisentraut.org> escreveu:
>
>     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.
>
>
> This new version you are not accepting subqueries, like previous ones. 
> But we can create an immutable SQL function which will do the same. 
> Wouldn't it be better to explain that on DOCs ?
>
> create table Orders(Order_ID integer not null primary key, Customer_ID 
> integer references Customer);
> create function lkCustomer(integer) returns text language sql 
> immutable as $function$select Name from Customer where Customer_ID = 
> $1;$function$;
> alter table Orders add lkCustomer text generated always as 
> (lkCustomer(Customer_ID)) stored;


This is lying to the planner, and you get to enjoy whatever breaks 
because of it.  A function that accesses external data is not immutable; 
it is stable at best.

-- 

Vik Fearing