Configuration
The first step of the installation procedure is to configure the
source tree for your system and choose the options you would like.
This is done by running the configure
script. For a
default installation simply enter:
./configure
This script will run a number of tests to determine values for various system dependent variables and detect any quirks of your operating system, and finally will create several files in the build tree to record what it found.
You can also run configure
in a directory outside
the source tree, and then build there, if you want to keep the build
directory separate from the original source files. This procedure is
called a
VPATH
build. Here's how:
mkdir build_dir
cd build_dir
/path/to/source/tree/configure [options go here]
make
The default configuration will build the server and utilities, as
well as all client applications and interfaces that require only a
C compiler. All files will be installed under
/usr/local/pgsql
by default.
You can customize the build and installation process by supplying one
or more command line options to configure
.
Typically you would customize the install location, or the set of
optional features that are built. configure
has a large number of options, which are described in
Section 17.4.1.
Also, configure
responds to certain environment
variables, as described in Section 17.4.2.
These provide additional ways to customize the configuration.
Build
To start the build, type either of:
make
make all
(Remember to use GNU make.) The build will take a few minutes depending on your hardware.
If you want to build everything that can be built, including the
documentation (HTML and man pages), and the additional modules
(contrib
), type instead:
make world
If you want to build everything that can be built, including the
additional modules (contrib
), but without
the documentation, type instead:
make world-bin
If you want to invoke the build from another makefile rather than
manually, you must unset MAKELEVEL
or set it to zero,
for instance like this:
build-postgresql: $(MAKE) -C postgresql MAKELEVEL=0 all
Failure to do that can lead to strange error messages, typically about missing header files.
Regression Tests
If you want to test the newly built server before you install it, you can run the regression tests at this point. The regression tests are a test suite to verify that PostgreSQL runs on your machine in the way the developers expected it to. Type:
make check
(This won't work as root; do it as an unprivileged user.) See Chapter 33 for detailed information about interpreting the test results. You can repeat this test at any later time by issuing the same command.
Installing the Files
If you are upgrading an existing system be sure to read Section 19.6, which has instructions about upgrading a cluster.
To install PostgreSQL enter:
make install
This will install files into the directories that were specified in Step 1. Make sure that you have appropriate permissions to write into that area. Normally you need to do this step as root. Alternatively, you can create the target directories in advance and arrange for appropriate permissions to be granted.
To install the documentation (HTML and man pages), enter:
make install-docs
If you built the world above, type instead:
make install-world
This also installs the documentation.
If you built the world without the documentation above, type instead:
make install-world-bin
You can use make install-strip
instead of
make install
to strip the executable files and
libraries as they are installed. This will save some space. If
you built with debugging support, stripping will effectively
remove the debugging support, so it should only be done if
debugging is no longer needed. install-strip
tries to do a reasonable job saving space, but it does not have
perfect knowledge of how to strip every unneeded byte from an
executable file, so if you want to save all the disk space you
possibly can, you will have to do manual work.
The standard installation provides all the header files needed for client application development as well as for server-side program development, such as custom functions or data types written in C.
Client-only installation: If you want to install only the client applications and interface libraries, then you can use these commands:
make -C src/bin install
make -C src/include install
make -C src/interfaces install
make -C doc install
src/bin
has a few binaries for server-only use,
but they are small.
Uninstallation:
To undo the installation use the command make
uninstall
. However, this will not remove any created directories.
Cleaning:
After the installation you can free disk space by removing the built
files from the source tree with the command make
clean
. This will preserve the files made by the configure
program, so that you can rebuild everything with make
later on. To reset the source tree to the state in which it was
distributed, use make distclean
. If you are going to
build for several platforms within the same source tree you must do
this and re-configure for each platform. (Alternatively, use
a separate build tree for each platform, so that the source tree
remains unmodified.)
If you perform a build and then discover that your configure
options were wrong, or if you change anything that configure
investigates (for example, software upgrades), then it's a good
idea to do make distclean
before reconfiguring and
rebuilding. Without this, your changes in configuration choices
might not propagate everywhere they need to.
configure
Options
configure
's command line options are explained below.
This list is not exhaustive (use ./configure --help
to get one that is). The options not covered here are meant for
advanced use-cases such as cross-compilation, and are documented in
the standard Autoconf documentation.
These options control where make install
will put
the files. The --prefix
option is sufficient for
most cases. If you have special needs, you can customize the
installation subdirectories with the other options described in this
section. Beware however that changing the relative locations of the
different subdirectories may render the installation non-relocatable,
meaning you won't be able to move it after installation.
(The man
and doc
locations are
not affected by this restriction.) For relocatable installs, you
might want to use the --disable-rpath
option
described later.
--prefix=PREFIX
Install all files under the directory PREFIX
instead of /usr/local/pgsql
. The actual
files will be installed into various subdirectories; no files
will ever be installed directly into the
PREFIX
directory.
--exec-prefix=EXEC-PREFIX
You can install architecture-dependent files under a
different prefix, EXEC-PREFIX
, than what
PREFIX
was set to. This can be useful to
share architecture-independent files between hosts. If you
omit this, then EXEC-PREFIX
is set equal to
PREFIX
and both architecture-dependent and
independent files will be installed under the same tree,
which is probably what you want.
--bindir=DIRECTORY
Specifies the directory for executable programs. The default
is
, which
normally means EXEC-PREFIX
/bin/usr/local/pgsql/bin
.
--sysconfdir=DIRECTORY
Sets the directory for various configuration files,
by default.
PREFIX
/etc
--libdir=DIRECTORY
Sets the location to install libraries and dynamically loadable
modules. The default is
.
EXEC-PREFIX
/lib
--includedir=DIRECTORY
Sets the directory for installing C and C++ header files. The
default is
.
PREFIX
/include
--datarootdir=DIRECTORY
Sets the root directory for various types of read-only data
files. This only sets the default for some of the following
options. The default is
.
PREFIX
/share
--datadir=DIRECTORY
Sets the directory for read-only data files used by the
installed programs. The default is
. Note that this has
nothing to do with where your database files will be placed.
DATAROOTDIR
--localedir=DIRECTORY
Sets the directory for installing locale data, in particular
message translation catalog files. The default is
.
DATAROOTDIR
/locale
--mandir=DIRECTORY
The man pages that come with PostgreSQL will be installed under
this directory, in their respective
man
subdirectories.
The default is x
.
DATAROOTDIR
/man
--docdir=DIRECTORY
Sets the root directory for installing documentation files,
except “man” pages. This only sets the default for
the following options. The default value for this option is
.
DATAROOTDIR
/doc/postgresql
--htmldir=DIRECTORY
The HTML-formatted documentation for
PostgreSQL will be installed under
this directory. The default is
.
DATAROOTDIR
Care has been taken to make it possible to install
PostgreSQL into shared installation locations
(such as /usr/local/include
) without
interfering with the namespace of the rest of the system. First,
the string “/postgresql
” is
automatically appended to datadir
,
sysconfdir
, and docdir
,
unless the fully expanded directory name already contains the
string “postgres
” or
“pgsql
”. For example, if you choose
/usr/local
as prefix, the documentation will
be installed in /usr/local/doc/postgresql
,
but if the prefix is /opt/postgres
, then it
will be in /opt/postgres/doc
. The public C
header files of the client interfaces are installed into
includedir
and are namespace-clean. The
internal header files and the server header files are installed
into private directories under includedir
. See
the documentation of each interface for information about how to
access its header files. Finally, a private subdirectory will
also be created, if appropriate, under libdir
for dynamically loadable modules.
The options described in this section enable building of various PostgreSQL features that are not built by default. Most of these are non-default only because they require additional software, as described in Section 17.2.
--enable-nls[=LANGUAGES
]
Enables Native Language Support (NLS),
that is, the ability to display a program's messages in a
language other than English.
LANGUAGES
is an optional space-separated
list of codes of the languages that you want supported, for
example --enable-nls='de fr'
. (The intersection
between your list and the set of actually provided
translations will be computed automatically.) If you do not
specify a list, then all available translations are
installed.
To use this option, you will need an implementation of the Gettext API.
--with-perl
Build the PL/Perl server-side language.
--with-python
Build the PL/Python server-side language.
--with-tcl
Build the PL/Tcl server-side language.
--with-tclconfig=DIRECTORY
Tcl installs the file tclConfig.sh
, which
contains configuration information needed to build modules
interfacing to Tcl. This file is normally found automatically
at a well-known location, but if you want to use a different
version of Tcl you can specify the directory in which to look
for tclConfig.sh
.
--with-icu
Build with support for the ICU library, enabling use of ICU collation features (see Section 24.2). This requires the ICU4C package to be installed. The minimum required version of ICU4C is currently 4.2.
By default,
pkg-config
will be used to find the required compilation options. This is
supported for ICU4C version 4.6 and later.
For older versions, or if pkg-config is
not available, the variables ICU_CFLAGS
and ICU_LIBS
can be specified
to configure
, like in this example:
./configure ... --with-icu ICU_CFLAGS='-I/some/where/include' ICU_LIBS='-L/some/where/lib -licui18n -licuuc -licudata'
(If ICU4C is in the default search path
for the compiler, then you still need to specify nonempty strings in
order to avoid use of pkg-config, for
example, ICU_CFLAGS=' '
.)
--with-llvm
Build with support for LLVM based JIT compilation (see Chapter 32). This requires the LLVM library to be installed. The minimum required version of LLVM is currently 3.9.
llvm-config
will be used to find the required compilation options.
llvm-config
, and then
llvm-config-$major-$minor
for all supported
versions, will be searched for in your PATH
. If
that would not yield the desired program,
use LLVM_CONFIG
to specify a path to the
correct llvm-config
. For example
./configure ... --with-llvm LLVM_CONFIG='/path/to/llvm/bin/llvm-config'
LLVM support requires a compatible
clang
compiler (specified, if necessary, using the
CLANG
environment variable), and a working C++
compiler (specified, if necessary, using the CXX
environment variable).
--with-lz4
Build with LZ4 compression support. This allows the use of LZ4 for compression of table data.
--with-ssl=LIBRARY
Build with support for SSL (encrypted)
connections. The only LIBRARY
supported is openssl
. This requires the
OpenSSL package to be installed.
configure
will check for the required
header files and libraries to make sure that your
OpenSSL installation is sufficient
before proceeding.
--with-openssl
Obsolete equivalent of --with-ssl=openssl
.
--with-gssapi
Build with support for GSSAPI authentication. On many systems, the
GSSAPI system (usually a part of the Kerberos installation) is not
installed in a location
that is searched by default (e.g., /usr/include
,
/usr/lib
), so you must use the options
--with-includes
and --with-libraries
in
addition to this option. configure
will check
for the required header files and libraries to make sure that
your GSSAPI installation is sufficient before proceeding.
--with-ldap
Build with LDAP
support for authentication and connection parameter lookup (see
Section 34.18 and
Section 21.10 for more information). On Unix,
this requires the OpenLDAP package to be
installed. On Windows, the default WinLDAP
library is used. configure
will check for the required
header files and libraries to make sure that your
OpenLDAP installation is sufficient before
proceeding.
--with-pam
--with-bsd-auth
Build with BSD Authentication support. (The BSD Authentication framework is currently only available on OpenBSD.)
--with-systemd
Build with support for systemd service notifications. This improves integration if the server is started under systemd but has no impact otherwise; see Section 19.3 for more information. libsystemd and the associated header files need to be installed to use this option.
--with-bonjour
Build with support for Bonjour automatic service discovery. This requires Bonjour support in your operating system. Recommended on macOS.
--with-uuid=LIBRARY
Build the uuid-ossp module
(which provides functions to generate UUIDs), using the specified
UUID library.
LIBRARY
must be one of:
bsd
to use the UUID functions found in FreeBSD, NetBSD,
and some other BSD-derived systems
e2fs
to use the UUID library created by
the e2fsprogs
project; this library is present in most
Linux systems and in macOS, and can be obtained for other
platforms as well
ossp
to use the OSSP UUID library
--with-ossp-uuid
Obsolete equivalent of --with-uuid=ossp
.
--with-libxml
Build with libxml2, enabling SQL/XML support. Libxml2 version 2.6.23 or later is required for this feature.
To detect the required compiler and linker options, PostgreSQL will
query pkg-config
, if that is installed and knows
about libxml2. Otherwise the program xml2-config
,
which is installed by libxml2, will be used if it is found. Use
of pkg-config
is preferred, because it can deal
with multi-architecture installations better.
To use a libxml2 installation that is in an unusual location, you
can set pkg-config
-related environment
variables (see its documentation), or set the environment variable
XML2_CONFIG
to point to
the xml2-config
program belonging to the libxml2
installation, or set the variables XML2_CFLAGS
and XML2_LIBS
. (If pkg-config
is
installed, then to override its idea of where libxml2 is you must
either set XML2_CONFIG
or set
both XML2_CFLAGS
and XML2_LIBS
to
nonempty strings.)
--with-libxslt
Build with libxslt, enabling the
xml2
module to perform XSL transformations of XML.
--with-libxml
must be specified as well.
The options described in this section allow disabling certain PostgreSQL features that are built by default, but which might need to be turned off if the required software or system features are not available. Using these options is not recommended unless really necessary.
--without-readline
Prevents use of the Readline library (and libedit as well). This option disables command-line editing and history in psql.
--with-libedit-preferred
Favors the use of the BSD-licensed libedit library rather than GPL-licensed Readline. This option is significant only if you have both libraries installed; the default in that case is to use Readline.
--without-zlib
Prevents use of the Zlib library. This disables support for compressed archives in pg_dump and pg_restore.
--disable-spinlocks
Allow the build to succeed even if PostgreSQL has no CPU spinlock support for the platform. The lack of spinlock support will result in very poor performance; therefore, this option should only be used if the build aborts and informs you that the platform lacks spinlock support. If this option is required to build PostgreSQL on your platform, please report the problem to the PostgreSQL developers.
--disable-atomics
Disable use of CPU atomic operations. This option does nothing on platforms that lack such operations. On platforms that do have them, this will result in poor performance. This option is only useful for debugging or making performance comparisons.
--disable-thread-safety
Disable the thread-safety of client libraries. This prevents concurrent threads in libpq and ECPG programs from safely controlling their private connection handles. Use this only on platforms with deficient threading support.
--with-includes=DIRECTORIES
DIRECTORIES
is a colon-separated list of
directories that will be added to the list the compiler
searches for header files. If you have optional packages
(such as GNU Readline) installed in a non-standard
location,
you have to use this option and probably also the corresponding
--with-libraries
option.
Example: --with-includes=/opt/gnu/include:/usr/sup/include
.
--with-libraries=DIRECTORIES
DIRECTORIES
is a colon-separated list of
directories to search for libraries. You will probably have
to use this option (and the corresponding
--with-includes
option) if you have packages
installed in non-standard locations.
Example: --with-libraries=/opt/gnu/lib:/usr/sup/lib
.
--with-system-tzdata=DIRECTORY
PostgreSQL includes its own time zone database,
which it requires for date and time operations. This time zone
database is in fact compatible with the IANA time zone
database provided by many operating systems such as FreeBSD,
Linux, and Solaris, so it would be redundant to install it again.
When this option is used, the system-supplied time zone database
in DIRECTORY
is used instead of the one
included in the PostgreSQL source distribution.
DIRECTORY
must be specified as an
absolute path. /usr/share/zoneinfo
is a
likely directory on some operating systems. Note that the
installation routine will not detect mismatching or erroneous time
zone data. If you use this option, you are advised to run the
regression tests to verify that the time zone data you have
pointed to works correctly with PostgreSQL.
This option is mainly aimed at binary package distributors who know their target operating system well. The main advantage of using this option is that the PostgreSQL package won't need to be upgraded whenever any of the many local daylight-saving time rules change. Another advantage is that PostgreSQL can be cross-compiled more straightforwardly if the time zone database files do not need to be built during the installation.
--with-extra-version=STRING
Append STRING
to the PostgreSQL version number. You
can use this, for example, to mark binaries built from unreleased Git
snapshots or containing custom patches with an extra version string,
such as a git describe
identifier or a
distribution package release number.
--disable-rpath
Do not mark PostgreSQL's executables
to indicate that they should search for shared libraries in the
installation's library directory (see --libdir
).
On most platforms, this marking uses an absolute path to the
library directory, so that it will be unhelpful if you relocate
the installation later. However, you will then need to provide
some other way for the executables to find the shared libraries.
Typically this requires configuring the operating system's
dynamic linker to search the library directory; see
Section 17.5.1 for more detail.
It's fairly common, particularly for test builds, to adjust the
default port number with --with-pgport
.
The other options in this section are recommended only for advanced
users.
--with-pgport=NUMBER
Set NUMBER
as the default port number for
server and clients. The default is 5432. The port can always
be changed later on, but if you specify it here then both
server and clients will have the same default compiled in,
which can be very convenient. Usually the only good reason
to select a non-default value is if you intend to run multiple
PostgreSQL servers on the same machine.
--with-krb-srvnam=NAME
The default name of the Kerberos service principal used
by GSSAPI.
postgres
is the default. There's usually no
reason to change this unless you are building for a Windows
environment, in which case it must be set to upper case
POSTGRES
.
--with-segsize=SEGSIZE
Set the segment size, in gigabytes. Large tables are
divided into multiple operating-system files, each of size equal
to the segment size. This avoids problems with file size limits
that exist on many platforms. The default segment size, 1 gigabyte,
is safe on all supported platforms. If your operating system has
“largefile” support (which most do, nowadays), you can use
a larger segment size. This can be helpful to reduce the number of
file descriptors consumed when working with very large tables.
But be careful not to select a value larger than is supported
by your platform and the file systems you intend to use. Other
tools you might wish to use, such as tar, could
also set limits on the usable file size.
It is recommended, though not absolutely required, that this value
be a power of 2.
Note that changing this value breaks on-disk database compatibility,
meaning you cannot use pg_upgrade
to upgrade to
a build with a different segment size.
--with-blocksize=BLOCKSIZE
Set the block size, in kilobytes. This is the unit
of storage and I/O within tables. The default, 8 kilobytes,
is suitable for most situations; but other values may be useful
in special cases.
The value must be a power of 2 between 1 and 32 (kilobytes).
Note that changing this value breaks on-disk database compatibility,
meaning you cannot use pg_upgrade
to upgrade to
a build with a different block size.
--with-wal-blocksize=BLOCKSIZE
Set the WAL block size, in kilobytes. This is the unit
of storage and I/O within the WAL log. The default, 8 kilobytes,
is suitable for most situations; but other values may be useful
in special cases.
The value must be a power of 2 between 1 and 64 (kilobytes).
Note that changing this value breaks on-disk database compatibility,
meaning you cannot use pg_upgrade
to upgrade to
a build with a different WAL block size.
Most of the options in this section are only of interest for
developing or debugging PostgreSQL.
They are not recommended for production builds, except
for --enable-debug
, which can be useful to enable
detailed bug reports in the unlucky event that you encounter a bug.
On platforms supporting DTrace, --enable-dtrace
may also be reasonable to use in production.
When building an installation that will be used to develop code inside
the server, it is recommended to use at least the
options --enable-debug
and --enable-cassert
.
--enable-debug
Compiles all programs and libraries with debugging symbols. This means that you can run the programs in a debugger to analyze problems. This enlarges the size of the installed executables considerably, and on non-GCC compilers it usually also disables compiler optimization, causing slowdowns. However, having the symbols available is extremely helpful for dealing with any problems that might arise. Currently, this option is recommended for production installations only if you use GCC. But you should always have it on if you are doing development work or running a beta version.
--enable-cassert
Enables assertion checks in the server, which test for many “cannot happen” conditions. This is invaluable for code development purposes, but the tests can slow down the server significantly. Also, having the tests turned on won't necessarily enhance the stability of your server! The assertion checks are not categorized for severity, and so what might be a relatively harmless bug will still lead to server restarts if it triggers an assertion failure. This option is not recommended for production use, but you should have it on for development work or when running a beta version.
--enable-tap-tests
Enable tests using the Perl TAP tools. This requires a Perl
installation and the Perl module IPC::Run
.
See Section 33.4 for more information.
--enable-depend
Enables automatic dependency tracking. With this option, the makefiles are set up so that all affected object files will be rebuilt when any header file is changed. This is useful if you are doing development work, but is just wasted overhead if you intend only to compile once and install. At present, this option only works with GCC.
--enable-coverage
If using GCC, all programs and libraries are compiled with code coverage testing instrumentation. When run, they generate files in the build directory with code coverage metrics. See Section 33.5 for more information. This option is for use only with GCC and when doing development work.
--enable-profiling
If using GCC, all programs and libraries are compiled so they
can be profiled. On backend exit, a subdirectory will be created
that contains the gmon.out
file containing
profile data.
This option is for use only with GCC and when doing development work.
--enable-dtrace
Compiles PostgreSQL with support for the dynamic tracing tool DTrace. See Section 28.5 for more information.
To point to the dtrace
program, the
environment variable DTRACE
can be set. This
will often be necessary because dtrace
is
typically installed under /usr/sbin
,
which might not be in your PATH
.
Extra command-line options for the dtrace
program
can be specified in the environment variable
DTRACEFLAGS
. On Solaris,
to include DTrace support in a 64-bit binary, you must specify
DTRACEFLAGS="-64"
. For example,
using the GCC compiler:
./configure CC='gcc -m64' --enable-dtrace DTRACEFLAGS='-64' ...
Using Sun's compiler:
./configure CC='/opt/SUNWspro/bin/cc -xtarget=native64' --enable-dtrace DTRACEFLAGS='-64' ...
configure
Environment Variables
In addition to the ordinary command-line options described above,
configure
responds to a number of environment
variables.
You can specify environment variables on the
configure
command line, for example:
./configure CC=/opt/bin/gcc CFLAGS='-O2 -pipe'
In this usage an environment variable is little different from a command-line option. You can also set such variables beforehand:
export CC=/opt/bin/gcc
export CFLAGS='-O2 -pipe'
./configure
This usage can be convenient because many programs' configuration scripts respond to these variables in similar ways.
The most commonly used of these environment variables are
CC
and CFLAGS
.
If you prefer a C compiler different from the one
configure
picks, you can set the
variable CC
to the program of your choice.
By default, configure
will pick
gcc
if available, else the platform's
default (usually cc
). Similarly, you can override the
default compiler flags if needed with the CFLAGS
variable.
Here is a list of the significant variables that can be set in this manner:
BISON
Bison program
CC
C compiler
CFLAGS
options to pass to the C compiler
CLANG
path to clang
program used to process source code
for inlining when compiling with --with-llvm
CPP
C preprocessor
CPPFLAGS
options to pass to the C preprocessor
CXX
C++ compiler
CXXFLAGS
options to pass to the C++ compiler
DTRACE
location of the dtrace
program
DTRACEFLAGS
options to pass to the dtrace
program
FLEX
Flex program
LDFLAGS
options to use when linking either executables or shared libraries
LDFLAGS_EX
additional options for linking executables only
LDFLAGS_SL
additional options for linking shared libraries only
LLVM_CONFIG
llvm-config
program used to locate the
LLVM installation
MSGFMT
msgfmt
program for native language support
PERL
Perl interpreter program. This will be used to determine the
dependencies for building PL/Perl. The default is
perl
.
PYTHON
Python interpreter program. This will be used to
determine the dependencies for building PL/Python. Also,
whether Python 2 or 3 is specified here (or otherwise
implicitly chosen) determines which variant of the PL/Python
language becomes available. See
Section 46.1
for more information. If this is not set, the following are probed
in this order: python python3 python2
.
TCLSH
Tcl interpreter program. This will be used to
determine the dependencies for building PL/Tcl.
If this is not set, the following are probed in this
order: tclsh tcl tclsh8.6 tclsh86 tclsh8.5 tclsh85
tclsh8.4 tclsh84
.
XML2_CONFIG
xml2-config
program used to locate the
libxml2 installation
Sometimes it is useful to add compiler flags after-the-fact to the set
that were chosen by configure
. An important example is
that gcc's -Werror
option cannot be included
in the CFLAGS
passed to configure
, because
it will break many of configure
's built-in tests. To add
such flags, include them in the COPT
environment variable
while running make
. The contents of COPT
are added to both the CFLAGS
and LDFLAGS
options set up by configure
. For example, you could do
make COPT='-Werror'
or
export COPT='-Werror'
make
If using GCC, it is best to build with an optimization level of
at least -O1
, because using no optimization
(-O0
) disables some important compiler warnings (such
as the use of uninitialized variables). However, non-zero
optimization levels can complicate debugging because stepping
through compiled code will usually not match up one-to-one with
source code lines. If you get confused while trying to debug
optimized code, recompile the specific files of interest with
-O0
. An easy way to do this is by passing an option
to make: make PROFILE=-O0 file.o
.
The COPT
and PROFILE
environment variables are
actually handled identically by the PostgreSQL
makefiles. Which to use is a matter of preference, but a common habit
among developers is to use PROFILE
for one-time flag
adjustments, while COPT
might be kept set all the time.