| Server IP : 103.119.228.120 / Your IP : 3.129.69.134 Web Server : Apache System : Linux v8.techscape8.com 3.10.0-1160.119.1.el7.tuxcare.els2.x86_64 #1 SMP Mon Jul 15 12:09:18 UTC 2024 x86_64 User : nobody ( 99) PHP Version : 5.6.40 Disable Function : shell_exec,symlink,system,exec,proc_get_status,proc_nice,proc_terminate,define_syslog_variables,syslog,openlog,closelog,escapeshellcmd,passthru,ocinum cols,ini_alter,leak,listen,chgrp,apache_note,apache_setenv,debugger_on,debugger_off,ftp_exec,dl,dll,myshellexec,proc_open,socket_bind,proc_close,escapeshellarg,parse_ini_filepopen,fpassthru,exec,passthru,escapeshellarg,escapeshellcmd,proc_close,proc_open,ini_alter,popen,show_source,proc_nice,proc_terminate,proc_get_status,proc_close,pfsockopen,leak,apache_child_terminate,posix_kill,posix_mkfifo,posix_setpgid,posix_setsid,posix_setuid,dl,symlink,shell_exec,system,dl,passthru,escapeshellarg,escapeshellcmd,myshellexec,c99_buff_prepare,c99_sess_put,fpassthru,getdisfunc,fx29exec,fx29exec2,is_windows,disp_freespace,fx29sh_getupdate,fx29_buff_prepare,fx29_sess_put,fx29shexit,fx29fsearch,fx29ftpbrutecheck,fx29sh_tools,fx29sh_about,milw0rm,imagez,sh_name,myshellexec,checkproxyhost,dosyayicek,c99_buff_prepare,c99_sess_put,c99getsource,c99sh_getupdate,c99fsearch,c99shexit,view_perms,posix_getpwuid,posix_getgrgid,posix_kill,parse_perms,parsesort,view_perms_color,set_encoder_input,ls_setcheckboxall,ls_reverse_all,rsg_read,rsg_glob,selfURL,dispsecinfo,unix2DosTime,addFile,system,get_users,view_size,DirFiles,DirFilesWide,DirPrintHTMLHeaders,GetFilesTotal,GetTitles,GetTimeTotal,GetMatchesCount,GetFileMatchesCount,GetResultFiles,fs_copy_dir,fs_copy_obj,fs_move_dir,fs_move_obj,fs_rmdir,SearchText,getmicrotime MySQL : ON | cURL : ON | WGET : ON | Perl : ON | Python : ON | Sudo : ON | Pkexec : ON Directory : /usr/local/ssl/share/doc/postgresql-9.2.24/html/ |
Upload File : |
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<HTML
><HEAD
><TITLE
>Template Databases</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
REV="MADE"
HREF="mailto:pgsql-docs@postgresql.org"><LINK
REL="HOME"
TITLE="PostgreSQL 9.2.24 Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Managing Databases"
HREF="managing-databases.html"><LINK
REL="PREVIOUS"
TITLE="Creating a Database"
HREF="manage-ag-createdb.html"><LINK
REL="NEXT"
TITLE="Database Configuration"
HREF="manage-ag-config.html"><LINK
REL="STYLESHEET"
TYPE="text/css"
HREF="stylesheet.css"><META
HTTP-EQUIV="Content-Type"
CONTENT="text/html; charset=ISO-8859-1"><META
NAME="creation"
CONTENT="2017-11-06T22:43:11"></HEAD
><BODY
CLASS="SECT1"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="5"
ALIGN="center"
VALIGN="bottom"
><A
HREF="index.html"
>PostgreSQL 9.2.24 Documentation</A
></TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
TITLE="Creating a Database"
HREF="manage-ag-createdb.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="managing-databases.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 21. Managing Databases</TD
><TD
WIDTH="20%"
ALIGN="right"
VALIGN="top"
><A
TITLE="Database Configuration"
HREF="manage-ag-config.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="MANAGE-AG-TEMPLATEDBS"
>21.3. Template Databases</A
></H1
><P
> <TT
CLASS="COMMAND"
>CREATE DATABASE</TT
> actually works by copying an existing
database. By default, it copies the standard system database named
<TT
CLASS="LITERAL"
>template1</TT
>. Thus that
database is the <SPAN
CLASS="QUOTE"
>"template"</SPAN
> from which new databases are
made. If you add objects to <TT
CLASS="LITERAL"
>template1</TT
>, these objects
will be copied into subsequently created user databases. This
behavior allows site-local modifications to the standard set of
objects in databases. For example, if you install the procedural
language <SPAN
CLASS="APPLICATION"
>PL/Perl</SPAN
> in <TT
CLASS="LITERAL"
>template1</TT
>, it will
automatically be available in user databases without any extra
action being taken when those databases are created.
</P
><P
> There is a second standard system database named
<TT
CLASS="LITERAL"
>template0</TT
>. This
database contains the same data as the initial contents of
<TT
CLASS="LITERAL"
>template1</TT
>, that is, only the standard objects
predefined by your version of
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>. <TT
CLASS="LITERAL"
>template0</TT
>
should never be changed after the database cluster has been
initialized. By instructing
<TT
CLASS="COMMAND"
>CREATE DATABASE</TT
> to copy <TT
CLASS="LITERAL"
>template0</TT
> instead
of <TT
CLASS="LITERAL"
>template1</TT
>, you can create a <SPAN
CLASS="QUOTE"
>"virgin"</SPAN
> user
database that contains none of the site-local additions in
<TT
CLASS="LITERAL"
>template1</TT
>. This is particularly handy when restoring a
<TT
CLASS="LITERAL"
>pg_dump</TT
> dump: the dump script should be restored in a
virgin database to ensure that one recreates the correct contents
of the dumped database, without conflicting with objects that
might have been added to <TT
CLASS="LITERAL"
>template1</TT
> later on.
</P
><P
> Another common reason for copying <TT
CLASS="LITERAL"
>template0</TT
> instead
of <TT
CLASS="LITERAL"
>template1</TT
> is that new encoding and locale settings
can be specified when copying <TT
CLASS="LITERAL"
>template0</TT
>, whereas a copy
of <TT
CLASS="LITERAL"
>template1</TT
> must use the same settings it does.
This is because <TT
CLASS="LITERAL"
>template1</TT
> might contain encoding-specific
or locale-specific data, while <TT
CLASS="LITERAL"
>template0</TT
> is known not to.
</P
><P
> To create a database by copying <TT
CLASS="LITERAL"
>template0</TT
>, use:
</P><PRE
CLASS="PROGRAMLISTING"
>CREATE DATABASE <TT
CLASS="REPLACEABLE"
><I
>dbname</I
></TT
> TEMPLATE template0;</PRE
><P>
from the SQL environment, or:
</P><PRE
CLASS="PROGRAMLISTING"
>createdb -T template0 <TT
CLASS="REPLACEABLE"
><I
>dbname</I
></TT
></PRE
><P>
from the shell.
</P
><P
> It is possible to create additional template databases, and indeed
one can copy any database in a cluster by specifying its name
as the template for <TT
CLASS="COMMAND"
>CREATE DATABASE</TT
>. It is important to
understand, however, that this is not (yet) intended as
a general-purpose <SPAN
CLASS="QUOTE"
>"<TT
CLASS="COMMAND"
>COPY DATABASE</TT
>"</SPAN
> facility.
The principal limitation is that no other sessions can be connected to
the source database while it is being copied. <TT
CLASS="COMMAND"
>CREATE
DATABASE</TT
> will fail if any other connection exists when it starts;
during the copy operation, new connections to the source database
are prevented.
</P
><P
> Two useful flags exist in <TT
CLASS="LITERAL"
>pg_database</TT
> for each
database: the columns <TT
CLASS="LITERAL"
>datistemplate</TT
> and
<TT
CLASS="LITERAL"
>datallowconn</TT
>. <TT
CLASS="LITERAL"
>datistemplate</TT
>
can be set to indicate that a database is intended as a template for
<TT
CLASS="COMMAND"
>CREATE DATABASE</TT
>. If this flag is set, the database can be
cloned by any user with <TT
CLASS="LITERAL"
>CREATEDB</TT
> privileges; if it is not set,
only superusers and the owner of the database can clone it.
If <TT
CLASS="LITERAL"
>datallowconn</TT
> is false, then no new connections
to that database will be allowed (but existing sessions are not terminated
simply by setting the flag false). The <TT
CLASS="LITERAL"
>template0</TT
>
database is normally marked <TT
CLASS="LITERAL"
>datallowconn = false</TT
> to prevent its modification.
Both <TT
CLASS="LITERAL"
>template0</TT
> and <TT
CLASS="LITERAL"
>template1</TT
>
should always be marked with <TT
CLASS="LITERAL"
>datistemplate = true</TT
>.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> <TT
CLASS="LITERAL"
>template1</TT
> and <TT
CLASS="LITERAL"
>template0</TT
> do not have any special
status beyond the fact that the name <TT
CLASS="LITERAL"
>template1</TT
> is the default
source database name for <TT
CLASS="COMMAND"
>CREATE DATABASE</TT
>.
For example, one could drop <TT
CLASS="LITERAL"
>template1</TT
> and recreate it from
<TT
CLASS="LITERAL"
>template0</TT
> without any ill effects. This course of action
might be advisable if one has carelessly added a bunch of junk in
<TT
CLASS="LITERAL"
>template1</TT
>. (To delete <TT
CLASS="LITERAL"
>template1</TT
>,
it must have <TT
CLASS="LITERAL"
>pg_database.datistemplate = false</TT
>.)
</P
><P
> The <TT
CLASS="LITERAL"
>postgres</TT
> database is also created when a database
cluster is initialized. This database is meant as a default database for
users and applications to connect to. It is simply a copy of
<TT
CLASS="LITERAL"
>template1</TT
> and can be dropped and recreated if necessary.
</P
></BLOCKQUOTE
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="manage-ag-createdb.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="manage-ag-config.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Creating a Database</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="managing-databases.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Database Configuration</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>