From: | Greg Stark <stark(at)mit(dot)edu> |
---|---|
To: | Thomas Kellerer <spam_eater(at)gmx(dot)net> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: GSoC 2017 |
Date: | 2017-01-28 01:46:52 |
Message-ID: | CAM-w4HOmw9ZSzZorsvykPaCK7j2qtTJa9k5ithYFhzsqmrVn9Q@mail.gmail.com |
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Lists: | pgsql-hackers |
On 27 January 2017 at 14:52, Thomas Kellerer <spam_eater(at)gmx(dot)net> wrote:
>
> I don't have the exact syntax at hand, but it's something like this:
>
> create distinct type customer_id_type as integer;
> create distinct type order_id_type as integer;
>
> create table customers (id customer_id_type primary key);
> create table orders (id order_id_type primary key, customer_id
> customer_id_type not null);
That seems like a useful thing but it's not exactly the same use case.
Measurements with units and currency amounts both have the property
that you are likely to want to have a single column that uses
different units for different rows. You can aggregate across them
without converting as long as you have an appropriate where clause or
group by clause -- GROUP BY units_of(debit_amount) for example.
--
greg
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