Subject: Re: Large Objects
References: <8d8248b8-8535-787b-5cb7-f081be778b70@purtz.de>
 <CAFj8pRCRGeVoa0ihxqSSWJHeHuMM8zaNBT0_StO9isSf2KBePQ@mail.gmail.com>
 <c93ecc97-a550-940f-0d26-e500db84aa7b@aklaver.com>
To: postgres list <pgsql-sql@postgresql.org>
From: =?UTF-8?Q?J=c3=bcrgen_Purtz?= <juergen@purtz.de>
Message-ID: <95bef507-ed75-2ca9-7914-2a243d326ab3@purtz.de>
Date: Fri, 7 Oct 2016 21:31:29 +0200
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My first concern is compatibility with the SQL standard - not the 
performance issues. Summarising the actual thread and mail 
https://www.postgresql.org/message-id/CAJNY3ivGORG1JSjZmop6k_OCJiLop5UCrWkm6NtwEVZhZpFRUw%40mail.gmail.com 
(ff.) I want to state:

- There are 3 (main) character data types: a) character with fixed 
length b) character with variable size and a fix upper length limit and 
c) character with variable size and undeclared (but implementation 
dependent) upper length limit.

- Types a) and b) are named identical in the standard and in Postgres 
(CHAR/VARCHAR). Data type c) is named CLOB in the standard and TEXT in 
Postgres. Why this different wording, if there is no real difference 
between the terms?

- Our documentation says that Postgres does not support feature T041 of 
the standard. But functions like LENGTH, LOWER, TRIM, UPPER, 
CONCATENATION, ... works well on TEXT.

Do we have some people in the standardisation committees (ANSI, BSI, 
DIN, JISC, ...), who represents the Postgres interests at this level?

Kind regards, Jürgen


On 07.10.2016 15:19, Adrian Klaver wrote:
> On 10/07/2016 12:25 AM, Pavel Stehule wrote:
>> Hi
>>
>> 2016-10-07 9:10 GMT+02:00 Jürgen Purtz <juergen@purtz.de
>> <mailto:juergen@purtz.de>>:
>>
>>     a) What is the distinction between our data type TEXT and the
>>     SQL:2011 data type CLOB which we do not support (T041)?
>>
>>
>> TEXT type is classic type - you can do any available operation directly
>> there. You don't need special conversions.
>>
>>
>>
>>     b) Is there a distinction between the two Postgres data types TEXT
>>     and "CHARACTER VARYING without specifying a length" - or are they
>>     only synonym terms without different functionalities and 
>> capabilities?
>>
>>
>> TEXT and varchar are pretty same types - you cannot to set limit over
>> TEXT type - only this is visible difference
>
> See also:
>
> https://www.postgresql.org/message-id/998.1474901921%40sss.pgh.pa.us
>
>>
>> Regards
>>
>> Pavel
>>
>>
>>
>>     Kind regards, Jürgen
>>
>>
>>
>>
>>     --
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>
>


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