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Update porting list.

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Fix markup to get clean compile.
This commit is contained in:
Thomas G. Lockhart
2000-04-11 05:39:15 +00:00
parent d57046097a
commit bdf6c4f012
6 changed files with 18 additions and 113 deletions
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101
doc/src/sgml/advanced.sgml
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@@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/advanced.sgml,v 1.10 2000/04/07 13:30:58 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/advanced.sgml,v 1.11 2000/04/11 05:39:06 thomas Exp $
-->
<chapter id="advanced">
@@ -234,105 +234,6 @@ SELECT SAL_EMP.schedule[1:2][1:1]
</sect2>
</sect1>
<!--
We haven't had Time Travel for two or three years, so let's stop
mentioning it. - thomas 2000-04-02
<sect1>
<title>Time Travel</title>
<para>
As of <productname>Postgres</productname> v6.2, <emphasis>time
travel is no longer supported</emphasis>. There are
several reasons for this: performance impact, storage size, and a
pg_time file which grows
toward infinite size in a short period of time.
</para>
<para>
New features such as triggers allow one to mimic the behavior of
time travel when desired, without
incurring the overhead when it is not needed (for most users, this
is most of the time).
See examples in the <filename>contrib</filename> directory for
more information.
</para>
<note>
<title>Time travel is deprecated</title>
<para>
The remaining text in this section is retained only until it can
be rewritten in the context
of new techniques to accomplish the same purpose.
Volunteers? - thomas 1998-01-12
</para>
</note>
<para>
<productname>Postgres</productname> supports the notion of time
travel. This feature
allows a user to run historical queries. For
example, to find the current population of Mariposa
city, one would query:
<programlisting>
SELECT * FROM cities WHERE name = 'Mariposa';
+---------+------------+----------+
|name | population | altitude |
+---------+------------+----------+
|Mariposa | 1320 | 1953 |
+---------+------------+----------+
</programlisting>
<productname>Postgres</productname> will automatically find the
version of Mariposa's
record valid at the current time.
One can also give a time range. For example to see the
past and present populations of Mariposa, one would
query:
<programlisting>
SELECT name, population
FROM cities['epoch', 'now']
WHERE name = 'Mariposa';
</programlisting>
where "epoch" indicates the beginning of the system
clock.
<note>
<para>
On Unix systems, this is always midnight, January 1, 1970 GMT.
</para>
</note>
</para>
<para>
If you have executed all of the examples so
far, then the above query returns:
<programlisting>
+---------+------------+
|name | population |
+---------+------------+
|Mariposa | 1200 |
+---------+------------+
|Mariposa | 1320 |
+---------+------------+
</programlisting>
</para>
<para>
The default beginning of a time range is the earliest
time representable by the system and the default end is
the current time; thus, the above time range can be
abbreviated as ``[,].''
</para>
</sect1>
-->
<sect1>
<title>More Advanced Features</title>