Обсуждение: Composite type: Primary Key and validation

On Mon, 2023-06-05 at 11:49 +0200, Lorusso Domenico wrote:
> I've a couple of questions about composite type.
> Suppose this composite type:
> CREATE TYPE my_type AS (
>     user_ts_start My_start_timestamp,
>     user_ts_end My_end_timestamp,
>     db_ts_start My_start_timestamp,
>     db_ts_end My_end_timestamp,
>     audit_record jsonb
> );
> My_start_timestamp is a domain of timestamp with default as now().
> My_end_timestamp is a domain of timestamp with default as infinite
>
>    1. May I use user_ts_start and/or db_ts_start has part of Primary Key of a table that contains a field of my_type?
>    2. to add an overall check constraint on the entire composite type, could be a valid
>       approach to create a domain based on my_type and add a custom function to validate it? (check_my_type(VALUE)).
>       In this way I've a dominan of composite type that contain others domain... what do you think?

Avoid using composite types as data types for a table column.
It adds complexity for no clear gain.

Yours,
Laurenz Albe

On 6/5/23 09:02, Laurenz Albe wrote:
> On Mon, 2023-06-05 at 11:49 +0200, Lorusso Domenico wrote:
>> I've a couple of questions about composite type.
>> Suppose this composite type:
>> CREATE TYPE my_type AS (
>>      user_ts_start My_start_timestamp,
>>      user_ts_end My_end_timestamp,
>>      db_ts_start My_start_timestamp,
>>      db_ts_end My_end_timestamp,
>>      audit_record jsonb
>> );
>> My_start_timestamp is a domain of timestamp with default as now().
>> My_end_timestamp is a domain of timestamp with default as infinite
>>
>>     1. May I use user_ts_start and/or db_ts_start has part of Primary Key of a table that contains a field of
my_type?
>>     2. to add an overall check constraint on the entire composite type, could be a valid
>>        approach to create a domain based on my_type and add a custom function to validate it?
(check_my_type(VALUE)).
>>        In this way I've a dominan of composite type that contain others domain... what do you think?
> Avoid using composite types as data types for a table column.
> It adds complexity for no clear gain.

Isn't now() also a bad idea, since it's the "now" at the start of the 
transaction?

Better to use clock_timestamp().

-- 
Born in Arizona, moved to Babylonia.

On 6/5/23 08:06, Lorusso Domenico wrote:
> Thank's, you are right, I've the same doubts.
> A composite type is useful because I've to add all these information on 
> many tables and because it more easy to pass all these informations to 
> functions that have to ensure the right format and evaluation.

I do that with a Sqitch(https://sqitch.org/) template, the relevant part 
being:

...

CREATE TABLE [% IF schema %][% schema %][% ELSE %]schema_name[% END 
%].[% IF table %][% table %][% ELSE %]table_name[% END %](
     line_id         integer GENERATED ALWAYS AS IDENTITY PRIMARY KEY,

     ts_insert       timestamptz NOT NULL DEFAULT now(),
     ts_update       timestamptz,
     user_insert     varchar(20) NOT NULL DEFAULT "session_user"(),
     user_update     varchar(20)
);

...

I then add the table specific fields after Sqitch creates the deploy 
script from the template.

> 
> Talking about first point I could use the "table inheritance", but I've 
> to reset all constraints for each table :-(
> 

> -- 
> Domenico L.
> 
> per stupire mezz'ora basta un libro di storia,
> io cercai di imparare la Treccani a memoria... [F.d.A.]

-- 
Adrian Klaver
adrian.klaver@aklaver.com

On Mon, 2023-06-05 at 17:06 +0200, Lorusso Domenico wrote:
> A composite type is useful because I've to add all these information on many tables and because
> it more easy to pass all these informations to functions that have to ensure the right format and evaluation.
>
> Talking about first point I could use the "table inheritance", but I've to reset all constraints for each table :-(

Inheritance is actually a very good way to do this.
You don't inherit constraints, but at least the column definitions.

Yours,
Laurenz Albe

On 6/5/23 11:19 AM, Lorusso Domenico wrote:
> thank's Adrian, my problem is I've to use CloudSql, so I can't install 
> extensions not verified by google...

It is not actually an extension, it is PERL program. Though I'm guessing 
that will still be an issue.

-- 
Adrian Klaver
adrian.klaver@aklaver.com

Thank's, you are right, I've the same doubts.

A composite type is useful because I've to add all these information on many tables and because it more easy to pass all these informations to functions that have to ensure the right format and evaluation.

Talking about first point I could use the "table inheritance", but I've to reset all constraints for each table :-(

Il giorno lun 5 giu 2023 alle ore 16:02 Laurenz Albe <laurenz.albe@cybertec.at> ha scritto:

On Mon, 2023-06-05 at 11:49 +0200, Lorusso Domenico wrote:
> I've a couple of questions about composite type.
> Suppose this composite type:
> CREATE TYPE my_type AS (
>     user_ts_start My_start_timestamp,
>     user_ts_end My_end_timestamp,
>     db_ts_start My_start_timestamp,
>     db_ts_end My_end_timestamp,
>     audit_record jsonb
> );
> My_start_timestamp is a domain of timestamp with default as now().
> My_end_timestamp is a domain of timestamp with default as infinite
>
>    1. May I use user_ts_start and/or db_ts_start has part of Primary Key of a table that contains a field of my_type?
>    2. to add an overall check constraint on the entire composite type, could be a valid
>       approach to create a domain based on my_type and add a custom function to validate it? (check_my_type(VALUE)).
>       In this way I've a dominan of composite type that contain others domain... what do you think?

Avoid using composite types as data types for a table column.
It adds complexity for no clear gain.

Yours,
Laurenz Albe

--

Domenico L.

per stupire mezz'ora basta un libro di storia,
io cercai di imparare la Treccani a memoria... [F.d.A.]