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Re: Trying to understand pg_get_expr()
4+ messages / 2 participants
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* Re: Trying to understand pg_get_expr()
@ 2026-03-17 20:19  Adrian Klaver <[email protected]>
  0 siblings, 1 reply; 4+ messages in thread

From: Adrian Klaver @ 2026-03-17 20:19 UTC (permalink / raw)
  To: Marcos Pegoraro <[email protected]>; +Cc: pgsql-general

On 3/17/26 1:08 PM, Marcos Pegoraro wrote:
> Em ter., 17 de mar. de 2026 às 16:31, Adrian Klaver 
> <[email protected] <mailto:[email protected]>> escreveu:
> 
>     Why does the = 'test' not return anything?
> 
> 
> for me pg_get_expr(adbin, adrelid) returns 'test'::character varying
> so it differs from 'test'

I should have indicated I tried casting:

SELECT
     adrelid::regclass,
     pg_typeof(pg_get_expr(adbin, adrelid)),
     pg_get_expr(adbin, adrelid)
FROM
     pg_attrdef
WHERE
     adrelid = 'default_test'::regclass
     AND pg_get_expr(adbin, 0) = 'test'::character varying;

  adrelid | pg_typeof | pg_get_expr
---------+-----------+-------------

I also tried other combinations of casting both sides of "=" and it 
still did not work.




> 
> regards
> Marcos


-- 
Adrian Klaver
[email protected]






^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Trying to understand pg_get_expr()
@ 2026-03-17 20:26  Marcos Pegoraro <[email protected]>
  parent: Adrian Klaver <[email protected]>
  0 siblings, 1 reply; 4+ messages in thread

From: Marcos Pegoraro @ 2026-03-17 20:26 UTC (permalink / raw)
  To: Adrian Klaver <[email protected]>; +Cc: pgsql-general

Em ter., 17 de mar. de 2026 às 17:19, Adrian Klaver <
[email protected]> escreveu:

> I also tried other combinations of casting both sides of "=" and it
> still did not work.
>

"'test'::character varying" is the result of that function, not type of test
This should work
AND pg_get_expr(adbin, adrelid) = $$'test'::character varying$$;

regards
Marcos


^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Trying to understand pg_get_expr()
@ 2026-03-17 20:36  Adrian Klaver <[email protected]>
  parent: Marcos Pegoraro <[email protected]>
  0 siblings, 1 reply; 4+ messages in thread

From: Adrian Klaver @ 2026-03-17 20:36 UTC (permalink / raw)
  To: Marcos Pegoraro <[email protected]>; +Cc: pgsql-general

On 3/17/26 1:26 PM, Marcos Pegoraro wrote:
> Em ter., 17 de mar. de 2026 às 17:19, Adrian Klaver 
> <[email protected] <mailto:[email protected]>> escreveu:
> 
>     I also tried other combinations of casting both sides of "=" and it
>     still did not work.
> 
> 
> "'test'::character varying" is the result of that function, not type of test
> This should work
> AND pg_get_expr(adbin, adrelid) = $$'test'::character varying$$;

Yeah that worked.

It begs the question then, in:

SELECT
     adrelid::regclass,
     pg_typeof(pg_get_expr(adbin, adrelid)),
     pg_get_expr(adbin, adrelid)
FROM
     pg_attrdef
WHERE
     adrelid = 'default_test'::regclass;

  adrelid    | pg_typeof |        pg_get_expr
--------------+-----------+---------------------------
  default_test | text      | 'test'::character varying
  default_test | text      | 0

Why is the second case not?:

'0'::integer

> 
> regards
> Marcos
> 


-- 
Adrian Klaver
[email protected]






^ permalink  raw  reply  [nested|flat] 4+ messages in thread

* Re: Trying to understand pg_get_expr()
@ 2026-03-17 20:54  Marcos Pegoraro <[email protected]>
  parent: Adrian Klaver <[email protected]>
  0 siblings, 0 replies; 4+ messages in thread

From: Marcos Pegoraro @ 2026-03-17 20:54 UTC (permalink / raw)
  To: Adrian Klaver <[email protected]>; +Cc: pgsql-general

Em ter., 17 de mar. de 2026 às 17:36, Adrian Klaver <
[email protected]> escreveu:

> Why is the second case not?:
>
I don't know, but you can see that it's not only for integers

CREATE TABLE default_test (
     id integer,
     fld_1 varchar DEFAULT 'test',
     fld_2 integer DEFAULT 0,
     fld_3 date DEFAULT Current_Date,
     fld_4 timestamp DEFAULT Current_Timestamp,
     fld_5 text DEFAULT 'x',
     fld_6 boolean DEFAULT 'on',
     fld_7 int4range DEFAULT '[1,2)',
     fld_8 char DEFAULT '1'
);

SELECT
     atttypid::regtype,
     pg_get_expr(adbin, adrelid)
FROM pg_class c inner join
     pg_attribute a on c.oid = attrelid
  inner join pg_attrdef d on c.oid = d.adrelid and adnum = attnum
WHERE
     relname = 'default_test' and attnum > 0;

regards
Marcs


^ permalink  raw  reply  [nested|flat] 4+ messages in thread

end of thread, other threads:[~2026-03-17 20:54 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2026-03-17 20:19 Re: Trying to understand pg_get_expr() Adrian Klaver <[email protected]>
2026-03-17 20:26 ` Marcos Pegoraro <[email protected]>
2026-03-17 20:36   ` Adrian Klaver <[email protected]>
2026-03-17 20:54     ` Marcos Pegoraro <[email protected]>

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