Re: Chante domain type - Postgres 9.2

On 09/26/2016 07:38 AM, Rob Sargent wrote:
>
>
> On 09/26/2016 08:14 AM, Adrian Klaver wrote:
>> On 09/26/2016 06:54 AM, Thomas Kellerer wrote:
>>> Rakesh Kumar schrieb am 26.09.2016 um 15:08:
>>>>> You sound like you think that varchar(50) is somehow cheaper than
>>>>> text.
>>>>
>>>> The biggest impediment to text cols in other RDBMS is no index
>>>> allowed.
>>>> If PG has an elegant solution to that, then yes I see the point made
>>>> by the
>>>> original poster.
>>>
>>> Don't confuse Postgres' "text" data type with "text" in other DBMS.
>>
>> Just be aware that layers above the database often do not understand
>> that and will see text as a memo field. For instance in Django a text
>> field will get rendered as a Textarea widget whereas a varchar field
>> will be rendered as an TextInput widget. You can override that, but it
>> is extra work. Luckily Postgres has the notion of an unbounded varchar:
>>
>> https://www.postgresql.org/docs/9.5/static/datatype-character.html
>>
>> ".. If character varying is used without length specifier, the type
>> accepts strings of any size. The latter is a PostgreSQL extension."
>>
>> This allows you to have 'text' without it being called text, as stated
>> below.
>>
>>>
>>> There is no difference whatsoever between varchar and text in Postgres.

> Does that trick remove the overhead (length check) Tom mentioned upstream?

Should have said earlier, the other side of the story is it makes your
schema less portable. Since I gave up on that some time ago it is not
something that is my first concern.

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com