On Fri, Apr 01, 2011 at 03:52:22AM -0400, Noah Misch wrote:
> NumericLong has a 14-bit count of decimal digits for the dscale, giving that
> fractional digit limit. It stores the weight as a 16-bit signed count of
> base-10000 "digits" after the first. For example, 10^4-1 has weight 0, 10^4
> through 10^8 - 1 have weight 1, 10^8 has weight 2, etc. For purposes of
> hitting
> the positive limit, we have 15 bits of weight. Therefore, it can represent up
> to 2^15 * 4 = 2^17 digits.
OK; thanks also for the explaination.
>
> > --- a/doc/src/sgml/datatype.sgml
> > +++ b/doc/src/sgml/datatype.sgml
>
> There's a table further up on this page that lists of the range of each type,
> with "no limit" listed for numeric. It could use an update noting with the
> supported extremes and fractional digit limit.
OK.
Please find attached v2 of the numeric-doc patch, which takes into
account your remarks. In particular, numeric limits are now correct
and documented only in that table.
Best regards,
Dr. Gianni Ciolli - 2ndQuadrant Italia
PostgreSQL Training, Services and Support
gianni.cio...@2ndquadrant.it | www.2ndquadrant.it
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml
index 0bb6594..c426020 100644
--- a/doc/src/sgml/datatype.sgml
+++ b/doc/src/sgml/datatype.sgml
@@ -346,13 +346,13 @@
<entry><type>decimal</></entry>
<entry>variable</entry>
<entry>user-specified precision, exact</entry>
- <entry>no limit</entry>
+ <entry>up to 131072 digits before the decimal point; up to 16383 digits after the decimal point</entry>
</row>
<row>
<entry><type>numeric</></entry>
<entry>variable</entry>
<entry>user-specified precision, exact</entry>
- <entry>no limit</entry>
+ <entry>up to 131072 digits before the decimal point; up to 16383 digits after the decimal point</entry>
</row>
<row>
@@ -476,8 +476,8 @@
</indexterm>
<para>
- The type <type>numeric</type> can store numbers with up to 1000
- digits of precision and perform calculations exactly. It is
+ The type <type>numeric</type> can store numbers with a
+ large number of digits and perform calculations exactly. It is
especially recommended for storing monetary amounts and other
quantities where exactness is required. However, arithmetic on
<type>numeric</type> values is very slow compared to the integer
@@ -525,6 +525,15 @@ NUMERIC
explicitly.)
</para>
+ <note>
+ <para>
+ The maximum allowed precision when explicitely specified in the
+ type declaration is 1000; otherwise the current implementation
+ of the <type>NUMERIC</type> is subject to the limits described
+ in <xref linkend="datatype-numeric-table">.
+ </para>
+ </note>
+
<para>
If the scale of a value to be stored is greater than the declared
scale of the column, the system will round the value to the specified
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