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Another try at correctly explaining the difference between Postgres and 

SQL92 temp tables.  Possibly I got it right this time.
This commit is contained in:
Tom Lane 2003-04-14 18:08:58 +00:00
parent 0851e12244
commit 3f4f235f79
1 changed files with 16 additions and 9 deletions
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25
doc/src/sgml/ref/create_table.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table.sgml,v 1.65 2003/04/14 15:40:02 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table.sgml,v 1.66 2003/04/14 18:08:58 tgl Exp $
PostgreSQL documentation
-->
@ -828,14 +828,14 @@ CREATE TABLE distributors (
<para>
Although the syntax of <literal>CREATE TEMPORARY TABLE</literal>
resembles that of SQL92, the effect is not the same. In the standard,
temporary tables are associated with modules; a temporary table is created
just once and automatically exists (starting with empty contents) in every
session that uses the module.
<productname>PostgreSQL</productname> does not have modules, and
temporary tables are defined just once and automatically exist (starting
with empty contents) in every session that needs them.
<productname>PostgreSQL</productname> instead
requires each session to issue its own <literal>CREATE TEMPORARY
TABLE</literal> command for each temporary table to be used.
The notion of <literal>GLOBAL</literal> temporary tables found in SQL92
is not in <productname>PostgreSQL</productname> at all.
TABLE</literal> command for each temporary table to be used. This allows
different sessions to use the same temporary table name for different
purposes, whereas the spec's approach constrains all instances of a
given temporary table name to have the same table structure.
</para>
<note>
@ -846,6 +846,13 @@ CREATE TABLE distributors (
</para>
</note>
<para>
SQL92's distinction between global and local temporary tables
is not in <productname>PostgreSQL</productname>, since that distinction
depends on the concept of modules, which
<productname>PostgreSQL</productname> does not have.
</para>
<para>
The <literal>ON COMMIT</literal> clause for temporary tables
also resembles SQL92, but has some differences.
@ -853,7 +860,7 @@ CREATE TABLE distributors (
default behavior is <literal>ON COMMIT DELETE ROWS</>. However, the
default behavior in <productname>PostgreSQL</productname> is
<literal>ON COMMIT PRESERVE ROWS</literal>. The <literal>ON COMMIT
DROP</literal> option does not exist in SQL92 at all.
DROP</literal> option does not exist in SQL92.
</para>
</refsect2>