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Re: AW: Cast INTEGER to BIT confusion

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> On 15/08/2023 14:02 CEST [Quipsy] Markus Karg <karg@xxxxxxxxx> wrote:
>
> I just tried out your proposal on PostgreSQL 15.3 and this is the result:
>
> ERROR:  column "c" is of type bit but expression is of type integer
> LINE 5:   INSERT INTO t VALUES (1);
>                                 ^
> HINT:  You will need to rewrite or cast the expression.
>
> Apparently the search path is ignored?!
>
> -----Ursprüngliche Nachricht-----
> Von: Erik Wienhold <ewie@xxxxxxxxx> 
> Gesendet: Dienstag, 15. August 2023 13:48
> An: [Quipsy] Markus Karg <karg@xxxxxxxxx>; pgsql-general@xxxxxxxxxxxxxxxxxxxx
> Betreff: Re: Cast INTEGER to BIT confusion
>
> You could create a custom domain if you're only interested in values 0 and 1
> and don't use bit string functions.  The search path must be changed so that
> domain bit overrides pg_catalog.bit:
> 
> 	=# CREATE SCHEMA xxx;
> 	=# CREATE DOMAIN xxx.bit AS int;
> 	=# SET search_path = xxx, pg_catalog;
> 	=# CREATE TABLE t (c bit);
> 	=# INSERT INTO t VALUES (1);
> 	INSERT 0 1
>
> But I would do that only if the third-party code cannot be tweaked because
> the custom domain could be confusing.  It's also prone to errors as it relies
> on a specific search path order.  Also make sure that regular users cannot
> create objects in schema xxx that would override objects in pg_catalog.

Hmm, I thought that Postgres resolves all types through the search path, but
apparently that is not the case for built-in types.  I never used this to
override built-in types so this is a surprise to me.  (And obviously I haven't
tested the search path feature before posting.)

Neither [1] or [2] mention that special (?) case or if there's a distinction
between built-in types and user-defined types.  The USAGE privilege is required
according to [2] but I was testing as superuser anyway.

[1] https://www.postgresql.org/docs/15/ddl-schemas.html
[2] https://www.postgresql.org/docs/15/runtime-config-client.html#GUC-SEARCH-PATH

--
Erik






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