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Extend CREATE DATABASE to allow selection of a template database to be

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cloned, rather than always cloning template1.  Modify initdb to generate
two identical databases rather than one, template0 and template1.
Connections to template0 are disallowed, so that it will always remain
in its virgin as-initdb'd state.  pg_dumpall now dumps databases with
restore commands that say CREATE DATABASE foo WITH TEMPLATE = template0.
This allows proper behavior when there is user-added data in template1.
initdb forced!
This commit is contained in:
Tom Lane
2000-11-14 18:37:49 +00:00
parent 8a9315ca92
commit 2cf48ca04b
23 changed files with 515 additions and 311 deletions
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110
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 1.15 2000/10/05 19:48:17 momjian Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_database.sgml,v 1.16 2000/11/14 18:37:40 tgl Exp $
Postgres documentation
-->
@ -23,7 +23,10 @@ Postgres documentation
<date>1999-12-11</date>
</refsynopsisdivinfo>
<synopsis>
CREATE DATABASE <replaceable class="PARAMETER">name</replaceable> [ WITH LOCATION = '<replaceable class="parameter">dbpath</replaceable>' ]
CREATE DATABASE <replaceable class="PARAMETER">name</replaceable>
[ WITH [ LOCATION = '<replaceable class="parameter">dbpath</replaceable>' ]
[ TEMPLATE = <replaceable class="parameter">template</replaceable> ]
[ ENCODING = <replaceable class="parameter">encoding</replaceable> ] ]
</synopsis>
<refsect2 id="R2-SQL-CREATEDATABASE-1">
@ -48,8 +51,30 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable> [ WITH LOCATIO
<term><replaceable class="parameter">dbpath</replaceable></term>
<listitem>
<para>
An alternate location where to store the new database in the filesystem.
See below for caveats.
An alternate filesystem location in which to store the new database,
specified as a string literal;
or <literal>DEFAULT</literal> to use the default location.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">template</replaceable></term>
<listitem>
<para>
Name of template from which to create the new database,
or <literal>DEFAULT</literal> to use the default template
(<literal>template1</literal>).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">encoding</replaceable></term>
<listitem>
<para>
Multibyte encoding method to use in the new database. Specify
a string literal name (e.g., <literal>'SQL_ASCII'</literal>),
or an integer encoding number, or <literal>DEFAULT</literal>
to use the default encoding.
</para>
</listitem>
</varlistentry>
@ -98,11 +123,10 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable> [ WITH LOCATIO
</varlistentry>
<varlistentry>
<term><computeroutput>ERROR: Single quotes are not allowed in database names.</computeroutput></term>
<term><computeroutput>ERROR: Single quotes are not allowed in database paths.</computeroutput></term>
<term><computeroutput>ERROR: database path may not contain single quotes</computeroutput></term>
<listitem>
<para>
The database <replaceable class="parameter">name</replaceable> and
The database location
<replaceable class="parameter">dbpath</replaceable> cannot contain
single quotes. This is required so that the shell commands that
create the database directory can execute safely.
@ -111,18 +135,7 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable> [ WITH LOCATIO
</varlistentry>
<varlistentry>
<term><computeroutput>ERROR: The path 'xxx' is invalid.</computeroutput></term>
<listitem>
<para>
The expansion of the specified <replaceable class="parameter">dbpath</replaceable>
(see below) failed. Check the path you entered or make sure that the
environment variable you are referencing does exist.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><computeroutput>ERROR: createdb: May not be called in a transaction block.</computeroutput></term>
<term><computeroutput>ERROR: CREATE DATABASE: may not be called in a transaction block</computeroutput></term>
<listitem>
<para>
If you have an explicit transaction block in progress you cannot call
@ -133,6 +146,9 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable> [ WITH LOCATIO
<varlistentry>
<term><computeroutput>ERROR: Unable to create database directory '<replaceable>path</replaceable>'.</computeroutput></term>
</varlistentry>
<varlistentry>
<term><computeroutput>ERROR: Could not initialize database directory.</computeroutput></term>
<listitem>
<para>
@ -169,10 +185,10 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable> [ WITH LOCATIO
command.
</para>
<para>
If the path contains a slash, the leading part is interpreted
as an environment variable, which must be known to the
If the path name does not contain a slash, it is interpreted
as an environment variable name, which must be known to the
server process. This way the database administrator can
exercise control over at which locations databases can be created.
exercise control over locations in which databases can be created.
(A customary choice is, e.g., '<envar>PGDATA2</envar>'.)
If the server is compiled with <literal>ALLOW_ABSOLUTE_DBPATHS</literal>
(not so by default), absolute path names, as identified by
@ -181,6 +197,29 @@ CREATE DATABASE <replaceable class="PARAMETER">name</replaceable> [ WITH LOCATIO
are allowed as well.
</para>
<para>
By default, the new database will be created by cloning the standard
system database <literal>template1</>. A different template can be
specified by writing <literal>TEMPLATE =</>
<replaceable class="parameter">name</replaceable>. In particular,
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.
</para>
<para>
The optional encoding parameter allows selection of the database encoding,
if your server was compiled with multibyte encoding support. When not
specified, it defaults to the encoding used by the selected template
database.
</para>
<para>
Optional parameters can be written in any order, not only the order
illustrated above.
</para>
<refsect2 id="R2-SQL-CREATEDATABASE-3">
<refsect2info>
<date>1999-12-11</date>
@ -221,6 +260,33 @@ comment from Olly; response from Thomas...
Not sure if the dump/reload would guarantee that
the alternate data area gets refreshed though...
-->
<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>
</refsect2>
</refsect1>