Thread: Confusion about the range types

Confusion about the range types

From
Dino Maric
Date:
Hey!

This is first time I'm writing, so I hope I've done this correctly :)

I'm confused about how range types are returned when queried

When I insert range like this:

INSERT INTO public.tests
VALUES (int4range(7,8,'[]'))

or this

INSERT INTO public.tests
VALUES ('[7,8]')

----------------

After when querying table my return value for this column is not [7,8] but it is [7,9).
I found this behaviour confusing, because I want to insert 7-8 ranges (including upper value) and then present that range to a user.

Maybe I'm missing something :)



My PG version is
: PostgreSQL 14.0 on aarch64-apple-darwin20.6.0, compiled by Apple clang version 12.0.5 (clang-1205.0.22.9), 64-bit





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Re: Confusion about the range types

From
Tom Lane
Date:
Dino Maric <dinom@hey.com> writes:
> When I insert range like this:
> INSERT INTO public.tests
> VALUES (int4range(7,8,'[]'))
> After when querying table my return value for this column is not [7,8]
> but it is [7,9).
> I found this behaviour confusing, because I want to insert 7-8 ranges
> (including upper value) and then present that range to a user.

This is the effect of canonicalization, as explained here:

https://www.postgresql.org/docs/current/rangetypes.html#RANGETYPES-DISCRETE

If you don't like it you can make a range type with a different
canonicalization function, or no such function, but that might
have odd effects on the behavior of range comparison operators.

            regards, tom lane



Re: Confusion about the range types

From
Dino Maric
Date:
Thanks Tom, I understand.

But still it does feel a bit strange that value I'm storing is different when presenting.
For example I want to use range in healthcare app and value user stores it must be the same when presenting.
So in that case it is [7-8] and [7-9) are not the same thing :)



On January 7, 2023, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Dino Maric <dinom@hey.com> writes:
> When I insert range like this:
> INSERT INTO public.tests
> VALUES (int4range(7,8,'[]'))
> After when querying table my return value for this column is not [7,8]
> but it is [7,9).
> I found this behaviour confusing, because I want to insert 7-8 ranges
> (including upper value) and then present that range to a user.

This is the effect of canonicalization, as explained here:

https://www.postgresql.org/docs/current/rangetypes.html#RANGETYPES-DISCRETE

If you don't like it you can make a range type with a different
canonicalization function, or no such function, but that might
have odd effects on the behavior of range comparison operators.

 regards, tom lane

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