| Server IP : 103.119.228.120 / Your IP : 18.116.15.22 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/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
>Python 2 vs. Python 3</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="PL/Python - Python Procedural Language"
HREF="plpython.html"><LINK
REL="PREVIOUS"
TITLE="PL/Python - Python Procedural Language"
HREF="plpython.html"><LINK
REL="NEXT"
TITLE="PL/Python Functions"
HREF="plpython-funcs.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="PL/Python - Python Procedural Language"
HREF="plpython.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="top"
><A
HREF="plpython.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="60%"
ALIGN="center"
VALIGN="bottom"
>Chapter 42. PL/Python - Python Procedural Language</TD
><TD
WIDTH="20%"
ALIGN="right"
VALIGN="top"
><A
TITLE="PL/Python Functions"
HREF="plpython-funcs.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="PLPYTHON-PYTHON23"
>42.1. Python 2 vs. Python 3</A
></H1
><P
> PL/Python supports both the Python 2 and Python 3 language
variants. (The PostgreSQL installation instructions might contain
more precise information about the exact supported minor versions
of Python.) Because the Python 2 and Python 3 language variants
are incompatible in some important aspects, the following naming
and transitioning scheme is used by PL/Python to avoid mixing them:
<P
></P
></P><UL
><LI
><P
> The PostgreSQL language named <TT
CLASS="LITERAL"
>plpython2u</TT
>
implements PL/Python based on the Python 2 language variant.
</P
></LI
><LI
><P
> The PostgreSQL language named <TT
CLASS="LITERAL"
>plpython3u</TT
>
implements PL/Python based on the Python 3 language variant.
</P
></LI
><LI
><P
> The language named <TT
CLASS="LITERAL"
>plpythonu</TT
> implements
PL/Python based on the default Python language variant, which is
currently Python 2. (This default is independent of what any
local Python installations might consider to be
their <SPAN
CLASS="QUOTE"
>"default"</SPAN
>, for example,
what <TT
CLASS="FILENAME"
>/usr/bin/python</TT
> might be.) The
default will probably be changed to Python 3 in a distant future
release of PostgreSQL, depending on the progress of the
migration to Python 3 in the Python community.
</P
></LI
></UL
><P>
This scheme is analogous to the recommendations in <A
HREF="http://www.python.org/dev/peps/pep-0394/"
TARGET="_top"
>PEP 394</A
> regarding the
naming and transitioning of the <TT
CLASS="COMMAND"
>python</TT
> command.
</P
><P
> It depends on the build configuration or the installed packages
whether PL/Python for Python 2 or Python 3 or both are available.
</P
><DIV
CLASS="TIP"
><BLOCKQUOTE
CLASS="TIP"
><P
><B
>Tip: </B
> The built variant depends on which Python version was found during
the installation or which version was explicitly set using
the <TT
CLASS="ENVAR"
>PYTHON</TT
> environment variable;
see <A
HREF="install-procedure.html"
>Section 15.4</A
>. To make both variants of
PL/Python available in one installation, the source tree has to be
configured and built twice.
</P
></BLOCKQUOTE
></DIV
><P
> This results in the following usage and migration strategy:
<P
></P
></P><UL
><LI
><P
> Existing users and users who are currently not interested in
Python 3 use the language name <TT
CLASS="LITERAL"
>plpythonu</TT
> and
don't have to change anything for the foreseeable future. It is
recommended to gradually <SPAN
CLASS="QUOTE"
>"future-proof"</SPAN
> the code
via migration to Python 2.6/2.7 to simplify the eventual
migration to Python 3.
</P
><P
> In practice, many PL/Python functions will migrate to Python 3
with few or no changes.
</P
></LI
><LI
><P
> Users who know that they have heavily Python 2 dependent code
and don't plan to ever change it can make use of
the <TT
CLASS="LITERAL"
>plpython2u</TT
> language name. This will
continue to work into the very distant future, until Python 2
support might be completely dropped by PostgreSQL.
</P
></LI
><LI
><P
> Users who want to dive into Python 3 can use
the <TT
CLASS="LITERAL"
>plpython3u</TT
> language name, which will keep
working forever by today's standards. In the distant future,
when Python 3 might become the default, they might like to
remove the <SPAN
CLASS="QUOTE"
>"3"</SPAN
> for aesthetic reasons.
</P
></LI
><LI
><P
> Daredevils, who want to build a Python-3-only operating system
environment, can change the contents of
<A
HREF="catalog-pg-pltemplate.html"
><TT
CLASS="STRUCTNAME"
>pg_pltemplate</TT
></A
>
to make <TT
CLASS="LITERAL"
>plpythonu</TT
> be equivalent
to <TT
CLASS="LITERAL"
>plpython3u</TT
>, keeping in mind that this
would make their installation incompatible with most of the rest
of the world.
</P
></LI
></UL
><P>
</P
><P
> See also the
document <A
HREF="http://docs.python.org/py3k/whatsnew/3.0.html"
TARGET="_top"
>What's
New In Python 3.0</A
> for more information about porting to
Python 3.
</P
><P
> It is not allowed to use PL/Python based on Python 2 and PL/Python
based on Python 3 in the same session, because the symbols in the
dynamic modules would clash, which could result in crashes of the
PostgreSQL server process. There is a check that prevents mixing
Python major versions in a session, which will abort the session if
a mismatch is detected. It is possible, however, to use both
PL/Python variants in the same database, from separate sessions.
</P
></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="plpython.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="plpython-funcs.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>PL/Python - Python Procedural Language</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="plpython.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>PL/Python Functions</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>