Re: The question about the type numeric

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: "sure(dot)postgres" <sure(dot)postgres(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: The question about the type numeric
Date: 2014-04-16 15:08:57
Message-ID: CA+TgmobfzprBsXJh9DkT7d3QkVm=-hNCV8oOzRW3Ya_robEDEQ@mail.gmail.com
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On Tue, Apr 15, 2014 at 5:37 AM, sure.postgres <sure(dot)postgres(at)gmail(dot)com> wrote:
> Hi hackers,
>
> I am learning about numeric .
> The comment of NumericShort format is:
> * In the NumericShort format, the remaining 14 bits of the header word
> * (n_short.n_header) are allocated as follows: 1 for sign (positive or
> * negative), 6 for dynamic scale, and 7 for weight. In practice, most
> * commonly-encountered values can be represented this way.
>
> So the Max of the NumericShort format should be up to 508 digits before the
> decimal point.
> So the sign of the number 12345678901234567890123456789012345678901234567890
> 12345678901234567890123456789012345678901234567890123456789012345678901234567890
> 12345678901234567890123456789012345678901234567890123456789012345678901234567890
> 12345678901234567890123456789012345678901234567
> should be 0x807F.
> The number is 257 digits before the decimal point.
> But the sign is 0.
> So is there anything wrong?

I'm not sure I understand the question, but if it helps, the sign bit
will be set (1) for negative values and clear (0) for positive values.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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