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Remove not-really-standard implementation of CREATE TABLE's UNDER clause,

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and revert documentation to describe the existing INHERITS clause
instead, per recent discussion in pghackers.  Also fix implementation
of SQL_inheritance SET variable: it is not cool to look at this var
during the initial parsing phase, only during parse_analyze().  See
recent bug report concerning misinterpretation of date constants just
after a SET TIMEZONE command.  gram.y really has to be an invariant
transformation of the query string to a raw parsetree; anything that
can vary with time must be done during parse analysis.
This commit is contained in:
Tom Lane
2001-01-05 06:34:23 +00:00
parent e62c38d0fc
commit 2fb6cc9045
19 changed files with 226 additions and 172 deletions
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29
doc/src/sgml/advanced.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/advanced.sgml,v 1.19 2000/12/30 19:11:45 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/advanced.sgml,v 1.20 2001/01/05 06:34:15 tgl Exp $
-->
<chapter id="advanced">
@ -33,9 +33,9 @@ CREATE TABLE cities (
altitude int -- (in ft)
);
CREATE TABLE capitals UNDER cities (
CREATE TABLE capitals (
state char(2)
);
) INHERITS (cities);
</programlisting>
In this case, an instance of capitals <firstterm>inherits</firstterm> all
@ -64,12 +64,12 @@ CREATE TABLE capitals UNDER cities (
<para>
For example, the following query finds the names of all cities,
including state capitals, that are located at an altitude
over 500ft, the query is:
over 500ft:
<programlisting>
SELECT c.name, c.altitude
FROM cities c
WHERE c.altitude > 500;
SELECT name, altitude
FROM cities
WHERE altitude &gt; 500;
</programlisting>
which returns:
@ -89,8 +89,8 @@ SELECT c.name, c.altitude
<para>
On the other hand, the following query finds
all the cities, but not capital cities
that are situated at an attitude of 500ft or higher:
all the cities that are not state capitals and
are situated at an altitude of 500ft or higher:
<programlisting>
SELECT name, altitude
@ -109,7 +109,7 @@ SELECT name, altitude
<para>
Here the <quote>ONLY</quote> before cities indicates that the query should
be run over only cities and not classes below cities in the
be run over only the cities table, and not classes below cities in the
inheritance hierarchy. Many of the commands that we
have already discussed -- <command>SELECT</command>,
<command>UPDATE</command> and <command>DELETE</command> --
@ -121,13 +121,18 @@ SELECT name, altitude
<para>
In previous versions of <productname>Postgres</productname>, the
default was not to get access to child tables. This was found to
be error prone and is also in violation of SQL. Under the old
be error prone and is also in violation of SQL99. Under the old
syntax, to get the sub-classes you append "*" to the table name.
For example
<programlisting>
SELECT * from cities*;
</programlisting>
To get the old behavior, the set configuration option
You can still explicitly specify scanning child tables by appending
"*", as well as explicitly specify not scanning child tables by
writing <quote>ONLY</quote>. But beginning in version 7.1, the default
behavior for an undecorated table name is to scan its child tables
too, whereas before the default was not to do so. To get the old
default behavior, set the configuration option
<literal>SQL_Inheritance</literal> to off, e.g.,
<programlisting>
SET SQL_Inheritance TO OFF;