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Update description of timestamp types for 7.3 implementation.

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This commit is contained in:
Tom Lane 2002-10-31 22:18:42 +00:00
parent 1ce069b067
commit 676a7c02d6
1 changed files with 18 additions and 12 deletions
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doc/src/sgml/datatype.sgml
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@ -1,5 +1,5 @@
<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.105 2002/10/21 02:12:08 tgl Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.106 2002/10/31 22:18:42 tgl Exp $
--> -->
<chapter id="datatype"> <chapter id="datatype">
@ -1276,7 +1276,7 @@ SELECT b, char_length(b) FROM test2;
</thead> </thead>
<tbody> <tbody>
<row> <row>
<entry><type>timestamp [ (<replaceable>p</replaceable>) ] without time zone</type></entry> <entry><type>timestamp [ (<replaceable>p</replaceable>) ] [ without time zone ]</type></entry>
<entry>both date and time</entry> <entry>both date and time</entry>
<entry>8 bytes</entry> <entry>8 bytes</entry>
<entry>4713 BC</entry> <entry>4713 BC</entry>
@ -1284,7 +1284,7 @@ SELECT b, char_length(b) FROM test2;
<entry>1 microsecond / 14 digits</entry> <entry>1 microsecond / 14 digits</entry>
</row> </row>
<row> <row>
<entry><type>timestamp [ (<replaceable>p</replaceable>) ] [ with time zone ]</type></entry> <entry><type>timestamp [ (<replaceable>p</replaceable>) ] with time zone</type></entry>
<entry>both date and time</entry> <entry>both date and time</entry>
<entry>8 bytes</entry> <entry>8 bytes</entry>
<entry>4713 BC</entry> <entry>4713 BC</entry>
@ -1293,7 +1293,7 @@ SELECT b, char_length(b) FROM test2;
</row> </row>
<row> <row>
<entry><type>interval [ (<replaceable>p</replaceable>) ]</type></entry> <entry><type>interval [ (<replaceable>p</replaceable>) ]</type></entry>
<entry>for time intervals</entry> <entry>time intervals</entry>
<entry>12 bytes</entry> <entry>12 bytes</entry>
<entry>-178000000 years</entry> <entry>-178000000 years</entry>
<entry>178000000 years</entry> <entry>178000000 years</entry>
@ -1334,16 +1334,22 @@ SELECT b, char_length(b) FROM test2;
optional precision value <replaceable>p</replaceable> which optional precision value <replaceable>p</replaceable> which
specifies the number of fractional digits retained in the seconds specifies the number of fractional digits retained in the seconds
field. By default, there is no explicit bound on precision. The field. By default, there is no explicit bound on precision. The
effective limit of precision is determined by the underlying double allowed range of <replaceable>p</replaceable> is from 0 to 6.
precision floating-point number used to store values (in seconds
for <type>interval</type> and
in seconds since 2000-01-01 for <type>timestamp</type>). The
useful range of <replaceable>p</replaceable> is from 0 to about
6 for <type>timestamp</type>, but may be more for <type>interval</type>.
The system will accept <replaceable>p</replaceable> ranging from
0 to 13.
</para> </para>
<note>
<para>
When timestamps are stored as double precision floating-point
numbers (currently the default), the effective limit of precision
may be less than 6, since timestamp values are stored as seconds
since 2000-01-01. Microsecond precision is achieved for dates within
a few years of 2000-01-01, but the precision degrades for dates further
away. When timestamps are stored as eight-byte integers (a compile-time
option), microsecond precision is available over the full range of
values.
</para>
</note>
<para> <para>
Time zones, and time-zone conventions, are influenced by Time zones, and time-zone conventions, are influenced by
political decisions, not just earth geometry. Time zones around the political decisions, not just earth geometry. Time zones around the