Re: Decimal64 and Decimal128

From: Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Peter Geoghegan <pg(at)heroku(dot)com>, Feng Tian <ftian(at)vitessedata(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Decimal64 and Decimal128
Date: 2017-06-15 21:42:38
Message-ID: CAEepm=1KZOPBKBLOD7g9D4Hr0QSyqBOZDNUBB6a9A3MAUaiuzQ@mail.gmail.com
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On Fri, Sep 25, 2015 at 5:06 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> 2015-09-25 0:25 GMT+02:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>:
>>
>> On 9/24/15 3:35 PM, Peter Geoghegan wrote:
>>>
>>> I would worry about the implicit casts you've added. They might cause
>>> problems.
>>
>>
>> Given the cycle created between numeric->decimal and decimal->numeric, I
>> can pretty much guarantee they will. In any case, I don't think implicit
>> casting from numeric->decimal is a good idea since it can overflow. I'm not
>> sure that the other direction is safe either... I can't remember offhand if
>> casting correctly obeys typmod or not.
>>
>> BTW, have you talked to Pavel about making these changes to his code?
>> Seems a shame to needlessly fork it. :/
>
>
> yes, he talked with me, and I gave a agreement to continue/enhance/fork this
> project how will be necessary

Bumping this ancient thread to say that DECFLOAT appears to have
landed in the SQL standard. I haven't looked at SQL:2016 myself by I
just saw this on Markus Winand's Modern SQL blog:

"There is a new type decfloat[(<precision>)] (T076)."

http://modern-sql.com/blog/2017-06/whats-new-in-sql-2016

So far it's supported only by DB2 (inventor) and FirebirdSQL has just
announced support in the next release.

--
Thomas Munro
http://www.enterprisedb.com

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