Re: Is there a reason why Postgres doesn't have Byte or tinyint?

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От Mike Christensen
Тема Re: Is there a reason why Postgres doesn't have Byte or tinyint?
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Msg-id CABs1bs1H7sbniufZwYFVZw0Obxxz4q7nBG4mmQRbzhNANzCcXw@mail.gmail.com
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Ответ на Re: Is there a reason why Postgres doesn't have Byte or tinyint?  (Scott Marlowe <scott.marlowe@gmail.com>)
Ответы Re: Is there a reason why Postgres doesn't have Byte or tinyint?  ("Francisco Figueiredo Jr." <francisco@npgsql.org>)
Список pgsql-general
>>>>> According to the manuals, Postgres has smallint (2 byte), integer (4
>>>>> bytes) and bigint (8 bytes)..  I use a lot of structures with "bytes"
>>>>> in my code and it's kinda annoying to cast DB output from Int16 to
>>>>> Byte every time, especially since there's no explicit cast in .NET and
>>>>> you have to use System.Convert().
>>>>>
>>>>> Is there a work-around, or do people just cast or use Int16 in their
>>>>> data structures?  Just wondering..  I know on modern computers it
>>>>> probably doesn't make any difference anyway..
>>>>
>>>>
>>>> Is this just about programmer convenience or is it about space efficiency
>>>> in
>>>> the database?  BYTEA might help you.  Or try declaring a DOMAIN over
>>>> SMALLINT that limits allowed values to the range of a byte. -- Darren
>>>> Duncan
>>>
>>>
>>> This is purely programmer convenience.
>>>
>>> Basically, I want Npgsql to marshal the value as a .NET Byte type, if
>>> I can find a way to do that I'm happy.  Perhaps it's more of a Npgsql
>>> question, though I'm curious as to why Postgres doesn't have an
>>> intrinsic tinyint or byte type.
>>
>>
>> Maybe Postgres doesn't need a Byte type predefined because it gives you the
>> means to define the type yourself, such as using DOMAIN.
>>
>> Generally speaking, I believe it is more important for a type system to
>> provide the means for arbitrary user-defined types which can be used in all
>> the places as built-in-defined types, than to have large numbers of
>> built-in-defined types.
>
> Precisely.  postgresql's extensable nature allows you to build your
> own types as well.  If it's popular enough it'll make it into contrib,
> then maybe core.  My guess is that there's some non-trivial cost to
> maintaining each core type, and since a byte type isn't required by
> the SQL spec, it would take some effort to get a standard one included
> in the core.

That makes sense.

I guess my question is more of a NpgSql question then.  Is there a way
to create a custom PG type, and have npgsql serialize that type in a
dataset to a .NET Byte type?

I'd probably be better off posting on the npgsql mailing list, but
perhaps someone here knows as well..

Mike

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