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Diffstat (limited to 'doc/src/sgml/advanced.sgml')
| -rw-r--r-- | doc/src/sgml/advanced.sgml | 101 |
1 files changed, 1 insertions, 100 deletions
diff --git a/doc/src/sgml/advanced.sgml b/doc/src/sgml/advanced.sgml index af7030e392a..3444abfb42d 100644 --- a/doc/src/sgml/advanced.sgml +++ b/doc/src/sgml/advanced.sgml @@ -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> |