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Clean up treatment of creating/dropping databases in User's Guide and

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Admin Guide.  Move discussion of template databases out of footnotes
in CREATE DATABASE ref page and into a section of the Admin Guide.
Clean up various obsolete claims, do some copy-editing.
This commit is contained in:
Tom Lane
2001-11-18 00:38:00 +00:00
parent c9a85cb276
commit 0729c4a61f
4 changed files with 188 additions and 335 deletions
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48
doc/src/sgml/ref/create_database.sgml
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@@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_database.sgml,v 1.20 2001/09/13 15:55:24 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_database.sgml,v 1.21 2001/11/18 00:38:00 tgl Exp $
Postgres documentation
-->
@@ -202,7 +202,8 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable>
by writing <literal>TEMPLATE = template0</>, you can create a virgin
database containing only the standard objects predefined by your
version of Postgres. This is useful if you wish to avoid copying
any installation-local objects that may have been added to template1.
any installation-local objects that may have been added to
<literal>template1</>.
</para>
<para>
@@ -259,44 +260,11 @@ comment from Olly; response from Thomas...
-->
<para>
Although it is possible to copy a database other than template1 by
specifying its name as the template, this is not (yet) intended as
a general-purpose COPY DATABASE facility. In particular, it is
essential that the source database be idle (no data-altering transactions
in progress)
for the duration of the copying operation. CREATE DATABASE will check
that no backend processes (other than itself) are connected to
the source database at the start of the operation, but this does not
guarantee that changes cannot be made while the copy proceeds. Therefore,
we recommend that databases used as templates be treated as read-only.
</para>
<para>
Two useful flags exist in <literal>pg_database</literal> for each
database: <literal>datistemplate</literal> and
<literal>datallowconn</literal>. <literal>datistemplate</literal>
may be set to indicate that a database is intended as a template for
CREATE DATABASE. If this flag is set, the database may be cloned by
any user with CREATEDB privileges; if it is not set, only superusers
and the owner of the database may clone it.
If <literal>datallowconn</literal> is false, then no new connections
to that database will be allowed (but existing sessions are not killed
simply by setting the flag false). The <literal>template0</literal>
database is normally marked this way to prevent modification of it.
</para>
<para>
After preparing a template database, or making any changes to one,
it is a good idea to perform
<command>VACUUM FREEZE</> or <command>VACUUM FULL FREEZE</> in that
database. If this is done when there are no other open transactions
in the same database, then it is guaranteed that all tuples in the
database are <quote>frozen</> and will not be subject to transaction
ID wraparound problems. This is particularly important for a database
that will have <literal>datallowconn</literal> set to false, since it
will be impossible to do routine maintenance <command>VACUUM</>s on
such a database.
See the Administrator's Guide for more information.
Although it is possible to copy a database other than <literal>template1</>
by specifying its name as the template, this is not (yet) intended as
a general-purpose COPY DATABASE facility.
We recommend that databases used as templates be treated as read-only.
See the <citetitle>Administrator's Guide</> for more information.
</para>
</refsect2>
</refsect1>