# PgBouncer

Lightweight connection pooler for PostgreSQL.

Homepage: https://pgbouncer.github.io/

Sources, bugtracking: https://github.com/pgbouncer/pgbouncer/

## Building

GNU Make 3.81+ is required for building.

PgBouncer uses libevent for low-level socket handling. Libevent needs to be at least version 1.3b. Preferably 2.x as Libevent 2.x has proper async DNS implementation.

When this is installed just run:

    $ ./configure --prefix=/usr/local --with-libevent=libevent-prefix
    $ make
    $ make install

If the OS does not have libevent available as package, it can be downloaded from http://monkey.org/~provos/libevent/

If you are building from git, or are building for Windows, please see separate build instructions below.

## DNS lookup support

Starting from PgBouncer 1.4, it does hostname lookups at connect time instead just once at config load time. This requires proper async DNS implementation. Following list shows supported backends and their probing order:

Table 1. DNS backends
backend | parallel | EDNS0 (1) | /etc/hosts | SOA lookup (2) | note
--- | --- | --- | --- | --- | ---
c-ares | yes | yes | yes | yes | ipv6+CNAME buggy in ⇐1.10
udns | yes | yes | no | yes | ipv4-only
evdns, libevent 2.x | yes | no | yes | no | does not check /etc/hosts updates
getaddrinfo_a, glibc 2.9+ | yes | yes (3) | yes | no | N/A on non-linux
getaddrinfo, libc | no | yes (3) | yes | no | N/A on win32, requires pthreads
evdns, libevent 1.x | yes | no | no | no | buggy

1. EDNS0 is required to have more than 8 addresses behind one hostname.

2. SOA lookup is needed to re-check hostnames on zone serial change

3. To enable EDNS0, add `options edns0` to /etc/resolv.conf

`./configure` also has flags `--enable-evdns` and `--disable-evdns` which turn off automatic probing and force use of either `evdns` or `getaddrinfo_a()`.

## Building from GIT

Building PgBouncer from GIT requires that you fetch libusual submodule and generate the header and config files before you can run configure:

    $ git clone git://git.postgresql.org/git/pgbouncer.git
    $ cd pgbouncer
    $ git submodule init
    $ git submodule update
    $ ./autogen.sh
    $ ./configure ...
    $ make
    $ make install

Additional packages required: autoconf, automake, libtool, autoconf-archive, asciidoc 8.x, xmlto, and pkg-config.

## Building for WIN32

At the moment only build env tested is MINGW32 / MSYS. Cygwin and Visual $ANYTHING are untested. Libevent 2.x is required for DNS hostname lookup.

Then do the usual:

    $ ./configure ...
    $ make

If cross-compiling from Unix:

    $ ./configure --host=i586-mingw32msvc ...

## Running on WIN32

Running from command-line goes as usual, except -d (daemonize), -R (reboot) and -u (switch user) switches will not work.

To run pgbouncer as a Windows service, you need to configure `service_name` parameter to set name for service. Then:

    $ pgbouncer -regservice config.ini

To uninstall service:

    $ pgbouncer -unregservice config.ini

To use Windows Event Log, set "syslog = 1" in config file. But before you need to register pgbevent.dll:

    $ regsvr32 pgbevent.dll

To unregister it, do `regsvr32 /u pgbevent.dll`.