pgbouncer — a Postgres Pro connection pooler


On Linux systems:

pgbouncer [ -d ] [ -R ] [ -v ] [ -u user ] pgbouncer.ini

pgbouncer -V | -h

On Windows:

pgbouncer [ -v ] [ -u user ] pgbouncer.ini

pgbouncer -V | -h

To use pgbouncer as a Windows service:

pgbouncer.exe --regservice pgbouncer.ini

pgbouncer.exe --unregservice pgbouncer.ini


pgbouncer is a Postgres Pro connection pooler. Any target application can be connected to pgbouncer as if it were a Postgres Pro server, and pgbouncer will create a connection to the actual server, or it will reuse one of its existing connections.

The aim of pgbouncer is to lower the performance impact of opening new connections to Postgres Pro.

In order not to compromise transaction semantics for connection pooling, pgbouncer supports several types of pooling when rotating connections:

Session pooling

Most polite method. When a client connects, a server connection will be assigned to it for the whole duration the client stays connected. When the client disconnects, the server connection will be put back into the pool. This is the default method.

Transaction pooling

A server connection is assigned to a client only during a transaction. When pgbouncer notices that transaction is over, the server connection will be put back into the pool.

Statement pooling

Most aggressive method. The server connection will be put back into the pool immediately after a query completes. Multi-statement transactions are disallowed in this mode as they would break.

The administration interface of pgbouncer consists of some new SHOW commands available when connected to a special virtual database pgbouncer.

Quick Start

Basic setup and usage is as follows.

  1. Create a pgbouncer.ini file. Details in the pgbouncer(5) man page. Simple example:

    template1 = host=localhost dbname=template1 auth_user=someuser
    listen_port = 6432
    listen_addr = localhost
    auth_type = md5
    auth_file = userlist.txt
    logfile = pgbouncer.log
    pidfile =
    admin_users = someuser
  2. Create a userlist.txt file that contains the users allowed in:

    "someuser" "same_password_as_in_server"
  3. Launch pgbouncer:

    $ pgbouncer -d pgbouncer.ini


    The above command does not work on Windows systems. Instead, pgbouncer must be launched as a service that first needs to be registered, as follows:

    pgbouncer --regservice

  4. Have your application (or the psql client) connect to pgbouncer instead of directly to the Postgres Pro server:

    $ psql -p 6432 -U someuser template1
  5. Manage pgbouncer by connecting to the special administration database pgbouncer and issuing SHOW HELP; to begin:

    $ psql -p 6432 -U someuser pgbouncer
    pgbouncer=# SHOW HELP;
    NOTICE:  Console usage
      SET key = arg
  6. If you made changes to the pgbouncer.ini file, you can reload it with:

    pgbouncer=# RELOAD;


-d, --daemon

Run in the background. Without it, the process will run in the foreground. In daemon mode, setting pidfile as well as logfile or syslog is required. No log messages will be written to stderr after going into the background.


Does not work on Windows, pgbouncer needs to run as service there.

-R, --reboot

Do an online restart. That means connecting to the running process, loading the open sockets from it, and then using them. If there is no active process, boot normally.


Works only if OS supports Unix sockets and the unix_socket_dir is not disabled in configuration. Does not work on Windows. Does not work with TLS connections, they are dropped.

-u user, --user user

Switch to the given user on startup.

-v, --verbose

Increase verbosity. Can be used multiple times.

-q, --quiet

Be quiet: do not log to stderr. This does not affect logging verbosity, only that stderr is not to be used. For use in init.d scripts.

-V, --version

Show version.

-h, --help

Show short help.


Win32: Register to run as Windows service. The service_name configuration parameter value is used as the name to register under.


Win32: Unregister Windows service.

Admin Console

The console is available by connecting as normal to the database pgbouncer:

$ psql -p 6432 pgbouncer

Only users listed in the configuration parameters admin_users or stats_users are allowed to log in to the console. (Except when auth_mode=any, then any user is allowed in as a stats_user.)

Additionally, the user name pgbouncer is allowed to log in without password, if the login comes via the Unix socket and the client has same Unix user uid as the running process.

The admin console currently only supports the simple query protocol. Some drivers use the extended query protocol for all commands; these drivers will not work for this.

Show Commands

The SHOW commands output information. Each command is described below.


Shows statistics. In this and related commands, the total figures are since process start, the averages are updated every stats_period.


Statistics are presented per database.


Total number of SQL transactions pooled by pgbouncer.


Total number of SQL queries pooled by pgbouncer.


Total volume in bytes of network traffic received by pgbouncer.


Total volume in bytes of network traffic sent by pgbouncer.


Total number of microseconds spent by pgbouncer when connected to Postgres Pro in a transaction, either idle in transaction or executing queries.


Total number of microseconds spent by pgbouncer when actively connected to Postgres Pro, executing queries.


Time spent by clients waiting for a server, in microseconds. Updated when a client connection is assigned a backend connection.


Average transactions per second in last stat period.


Average queries per second in last stat period.


Average received (from clients) bytes per second.


Average sent (to clients) bytes per second.


Average transaction duration, in microseconds.


Average query duration, in microseconds.


Average time spent by clients waiting for a server that were assigned a backend connection within the current stats_period, in microseconds (average per second within that period).


Subset of SHOW STATS showing the total values (total_).


Subset of SHOW STATS showing the average values (avg_).


Like SHOW STATS but aggregated across all databases.



S, for server.


User name pgbouncer uses to connect to server.


Database name.


State of the pgbouncer server connection, one of active, idle, used, tested, new, active_cancel, or being_canceled.


IP address of Postgres Pro server.


Port of Postgres Pro server.


Connection start address on local machine.


Connection start port on local machine.


When the connection was made.


When last request was issued.


Not used for server connections.


Not used for server connections.


1 if the connection will be closed as soon as possible, because a configuration file reload or DNS update changed the connection information or RECONNECT was issued.


Address of internal object for this connection. Used as unique ID.


Address of client connection the server is paired with.


PID of backend server process. In case connection is made over Unix socket and OS supports getting process ID info, its OS PID. Otherwise it's extracted from cancel packet the server sent, which should be the PID in case the server is Postgres Pro, but it's a random number in case the server is another pgbouncer.


A string with TLS connection information, or empty if not using TLS.


A string containing the application_name set on the linked client connection, or empty if this is not set, or if there is no linked connection.



C, for client.


Client connected user.


Database name.


State of the client connection, one of active, waiting, active_cancel_req, or waiting_cancel_req.


IP address of the client.


Source port of the client.


Connection end address on local machine.


Connection end port on local machine.


Timestamp of connect time.


Timestamp of latest client request.


Current waiting time in seconds.


Microsecond part of the current waiting time.


Not used for clients.


Address of internal object for this connection. Used as unique ID.


Address of server connection the client is paired with.


Process ID, in case client connects over Unix socket and OS supports getting it.


A string with TLS connection information, or empty if not using TLS.


A string containing the application_name set by the client for this connection, or empty if this is not set.


A new pool entry is made for each couple of (database, user).


Database name.


User name.


Client connections that are either linked to server connections or are idle with no queries waiting to be processed.


Client connections that have sent queries but have not yet got a server connection.


Client connections that have forwarded query cancellations to the server and are waiting for the server response.


Client connections that have not forwarded query cancellations to the server yet.


Server connections that are linked to a client.


Server connections that are currently forwarding a cancel request.


Servers that normally could become idle but are waiting to do so until all in-flight cancel requests have completed that were sent to cancel a query on this server.


Server connections that are unused and immediately usable for client queries.


Server connections that have been idle for more than server_check_delay, so they need server_check_query to run on them before they can be used again.


Server connections that are currently running either server_reset_query or server_check_query.


Server connections currently in the process of logging in.


How long the first (oldest) client in the queue has waited, in seconds. If this starts increasing, then the current pool of servers does not handle requests quickly enough. The reason may be either an overloaded server or just too small of a pool_size setting.


Microsecond part of the maximum waiting time.


The pooling mode in use.


Show following internal information, in columns (not rows):


Count of databases.


Count of users.


Count of pools.


Count of free clients.


Count of used clients.


Count of clients in login state.


Count of free servers.


Count of used servers.


Count of DNS names in the cache.


Count of DNS zones in the cache.


Count of in-flight DNS queries.


Not used.



The user name.


The user's override pool_mode, or NULL if the default will be used instead.



Name of configured database entry.


Host pgbouncer connects to.


Port pgbouncer connects to.


Actual database name pgbouncer connects to.


When the user is part of the connection string, the connection between pgbouncer and Postgres Pro is forced to the given user, whatever the client user.


Maximum number of server connections.


Minimum number of server connections.


Maximum number of additional connections for this database.


The database's override pool_mode, or NULL if the default will be used instead.


Maximum number of allowed connections for this database, as set by max_db_connections, either globally or per database.


Current number of connections for this database.


1 if this database is currently paused, else 0.


1 if this database is currently disabled, else 0.


Internal command — shows list of file descriptors (FDs) in use with internal state attached to them.

When the connected user has the user name pgbouncer, connects through the Unix socket and has the same UID as the running process, the actual FDs are passed over the connection. This mechanism is used to do an online restart.


This does not work on Windows.

This command also blocks the internal event loop, so it should not be used while pgbouncer is in use.


File descriptor numeric value.


One of pooler, client or server.


User of the connection using the FD.


Database of the connection using the FD.


IP address of the connection using the FD, unix if a Unix socket is used.


Port used by the connection using the FD.


Cancel key for this connection.


File descriptor for corresponding server/client. NULL if idle.


Shows low-level information about sockets or only active sockets. This includes the information shown under SHOW CLIENTS and SHOW SERVERS as well as other more low-level information.


Show the current configuration settings, one per row, with the following columns:


Configuration variable name.


Configuration value.


Configuration default value.


Either yes or no, shows if the variable can be changed while running. If no, the variable can be changed only at boot-time. Use SET to change a variable at run time.


Shows low-level information about the current sizes of various internal memory allocations. The information presented is subject to change.


Show host names in DNS cache.


Host name.


How many seconds until next lookup.


Comma separated list of addresses.


Show DNS zones in cache.


Zone name.


Current serial.


Host names belonging to this zone.


Show the pgbouncer version string.

Process Controlling Commands

PAUSE [db]

pgbouncer tries to disconnect from all servers, first waiting for all queries to complete. The command will not return before all queries are finished. To be used at the time of database restart.

If database name is given, only that database will be paused.

New client connections to a paused database will wait until RESUME is called.


Reject all new client connections on the given database.


Allow new client connections after a previous DISABLE command.


Close each open server connection for the given database, or all databases, after it is released (according to the pooling mode), even if its lifetime is not up yet. New server connections can be made immediately and will connect as necessary according to the pool size settings.

This command is useful when the server connection setup has changed, for example to perform a gradual switchover to a new server. It is not necessary to run this command when the connection string in pgbouncer.ini has been changed and reloaded (see RELOAD) or when DNS resolution has changed, because then the equivalent of this command will be run automatically. This command is only necessary if something downstream of pgbouncer routes the connections.

After this command is run, there could be an extended period where some server connections go to an old destination and some server connections go to a new destination. This is likely only sensible when switching read-only traffic between read-only replicas, or when switching between nodes of a multimaster replication setup. If all connections need to be switched at the same time, PAUSE is recommended instead. To close server connections without waiting (for example, in emergency failover rather than gradual switchover scenarios), also consider KILL.


Immediately drop all client and server connections on given database.

New client connections to a killed database will wait until RESUME is called.


All socket buffers are flushed and pgbouncer stops listening for data on them. The command will not return before all buffers are empty. To be used at the time of pgbouncer online reboot.

New client connections to a suspended database will wait until RESUME is called.


Resume work from previous KILL, PAUSE, or SUSPEND command.


The pgbouncer process will exit.


The pgbouncer process will reload its configuration files and update changeable settings. This includes the main configuration file as well as the files specified by the settings auth_file and auth_hba_file.

pgbouncer notices when a configuration file reload changes the connection parameters of a database definition. An existing server connection to the old destination will be closed when the server connection is next released (according to the pooling mode), and new server connections will immediately use the updated connection parameters.


Wait until all server connections, either of the specified database or of all databases, have cleared the close_needed state (see the section called “SHOW SERVERS”). This can be called after a RECONNECT or RELOAD to wait until the respective configuration change has been fully activated, for example in switchover scripts.

Other Commands

SET key = arg

Changes a configuration setting (see also the section called “SHOW CONFIG”). For example:

SET log_connections = 1;
SET server_check_query = 'select 2';

(Note that this command is run on the pgbouncer admin console and sets pgbouncer settings. A SET command run on another database will be passed to the Postgres Pro backend like any other SQL command.)



Reload config. Same as issuing the command RELOAD on the console.


Safe shutdown. Same as issuing PAUSE and SHUTDOWN on the console.


Immediate shutdown. Same as issuing SHUTDOWN on the console.


Same as issuing PAUSE on the console.


Same as issuing RESUME on the console.

Libevent Settings

From the libevent documentation:

It is possible to disable support for epoll, kqueue, devpoll, poll, or select by setting the environment variable EVENT_NOEPOLL, EVENT_NOKQUEUE, EVENT_NODEVPOLL, EVENT_NOPOLL or EVENT_NOSELECT, respectively.

By setting the environment variable EVENT_SHOW_METHOD, libevent displays the kernel notification method that it uses.

pgbouncer.ini Configuration File

The configuration file is in the .ini format. Section names are between [ and ]. Lines starting with ; or # are taken as comments and ignored. The characters ; and # are not recognized as special when they appear later in the line.

Generic Settings


Specifies the log file. For daemonization (-d), either this or syslog has to be set. The log file is kept open, so after rotation, kill -HUP or on console RELOAD; should be done. On Windows, the service must be stopped and started.

Note that setting logfile does not by itself turn off logging to stderr. Use the command-line option -q or -d for that.

Default: not set


Specifies the PID file. Without pidfile set, daemonization (-d) is not allowed.

Default: not set


Specifies a list (comma-separated) of addresses where to listen for TCP connections. You may also use * meaning "listen on all addresses". When not set, only Unix socket connections are accepted.

Addresses can be specified numerically (IPv4/IPv6) or by name.

Default: not set


Which port to listen on. Applies to both TCP and Unix sockets.

Default: 6432


Specifies the location for Unix sockets. Applies to both the listening socket and server connections. If set to an empty string, Unix sockets are disabled. A value that starts with @ specifies that a Unix socket in the abstract namespace should be created (currently supported on Linux and Windows).

For online reboot (-R) to work, a Unix socket needs to be configured, and it needs to be in the file-system namespace.

Default: /tmp (empty on Windows)


File system mode for Unix socket. Ignored for sockets in the abstract namespace. Not supported on Windows.

Default: 0777


Group name to use for Unix socket. Ignored for sockets in the abstract namespace. Not supported on Windows.

Default: not set


If set, specifies the Unix user to change to after startup. Works only if pgbouncer is started as root or if it's already running as the given user.

Not supported on Windows.

Default: not set


Specifies when a server connection can be reused by other clients.


Server is released back to pool after client disconnects. Default.


Server is released back to pool after transaction finishes.


Server is released back to pool after query finishes. Transactions spanning multiple statements are disallowed in this mode.


Maximum number of client connections allowed.

When this setting is increased, then the file descriptor limits in the operating system might also have to be increased. Note that the number of file descriptors potentially used is more than max_client_conn. If each user connects under its own username to the server, the theoretical maximum used is:

max_client_conn + (max pool_size * total databases * total users)

If a database user is specified in the connection string (all users connect under the same user name), the theoretical maximum is:

max_client_conn + (max pool_size * total databases)

The theoretical maximum should never be reached, unless somebody deliberately crafts a special load for it. Still, it means you should set the number of file descriptors to a safely high number.

Search for ulimit in your favorite shell man page. Note: ulimit does not apply in a Windows environment.

Default: 100


How many server connections to allow per user/database pair. Can be overridden in the per-database configuration.

Default: 20


Add more server connections to pool if below this number. Improves the behavior when the normal load suddenly comes back after a period of total inactivity. The value is effectively capped at the pool size.

Default: 0 (disabled)


How many additional connections to allow to a pool (see reserve_pool_timeout). The 0 value disables this parameter.

Default: 0 (disabled)


If a client has not been serviced in this time, pgbouncer enables use of additional connections from the reserve pool. The 0 value disables this parameter. [seconds]

Default: 5.0


Do not allow more than this many server connections per database (regardless of user). This considers the pgbouncer database that the client has connected to, not the Postgres Pro database of the outgoing connection. This can also be set per database in the [databases] section.

Note that when you hit the limit, closing a client connection to one pool will not immediately allow a server connection to be established for another pool, because the server connection for the first pool is still open. Once the server connection closes (due to idle timeout), a new server connection will immediately be opened for the waiting pool.

Default: 0 (unlimited)


Do not allow more than this many server connections per user (regardless of database). This considers the pgbouncer user that is associated with a pool, which is either the user specified for the server connection or in absence of that the user the client has connected as. This can also be set per user in the [users] section.

Note that when you hit the limit, closing a client connection to one pool will not immediately allow a server connection to be established for another pool, because the server connection for the first pool is still open. Once the server connection closes (due to idle timeout), a new server connection will immediately be opened for the waiting pool.

Default: 0 (unlimited)


By default, pgbouncer reuses server connections in LIFO (last-in, first-out) manner, so that few connections get the most load. This gives best performance if you have a single server serving a database. But if there is a round-robin system behind a database address (TCP, DNS, or host list), then it is better if pgbouncer also uses connections in that manner, thus achieving uniform load.

Default: 0


By default, pgbouncer allows only parameters it can keep track of in startup packets: client_encoding, datestyle, timezone and standard_conforming_strings.

All other parameters will raise an error. To allow other parameters, they can be specified here, so that pgbouncer knows that they are handled by the admin and it can ignore them.

If you need to specify multiple values, use a comma-separated list (e.g. options,extra_float_digits).

Default: empty


Disable the Simple Query protocol (PQexec). Unlike the Extended Query protocol, Simple Query allows multiple queries in one packet, which allows some classes of SQL-injection attacks. Disabling it can improve security. Obviously, this means only clients that exclusively use the Extended Query protocol will stay working.

Default: 0


Add the client host address and port to the application name setting set on connection start. This helps in identifying the source of bad queries, etc. This logic applies only at the start of a connection. If application_name is later changed with SET, pgbouncer does not change it again.

Default: 0


Show location of current configuration file. Changing it will make pgbouncer use another configuration file for next RELOAD / SIGHUP.

Default: file from command line


Used on win32 service registration.

Default: pgbouncer


Alias for service_name.


Sets how often the averages shown in various SHOW commands are updated and how often aggregated statistics are written to the log (but see log_stats). [seconds]

Default: 60

Authentication Settings

pgbouncer handles its own client authentication and has its own database of users. These settings control this.


How to authenticate users.


The client must connect over TLS connection with a valid client certificate. The user name is then taken from the CommonName field from the certificate.


Use MD5-based password check. This is the default authentication method. auth_file may contain both MD5-encrypted and plain-text passwords. If md5 is configured and a user has a SCRAM secret, then SCRAM authentication is used automatically instead.


Use password check with SCRAM-SHA-256. auth_file has to contain SCRAM secrets or plain-text passwords. Note that SCRAM secrets can only be used for verifying the password of a client but not for logging into a server. To be able to use SCRAM on server connections, use plain-text passwords.


The clear-text password is sent over the wire. Deprecated.


No authentication is done. The user name must still exist in auth_file.


Like the trust method, but the user name given is ignored. Requires that all databases are configured to log in as a specific user. Additionally, the console database allows any user to log in as admin.


The actual authentication type is loaded from auth_hba_file. This allows different authentication methods for different access paths, for example: connections over Unix socket use peer authentication method, connections over TCP must use TLS.


Pluggable Authentication Modules (PAM) method is used to authenticate users, auth_file is ignored. This method is not compatible with databases using the auth_user option. The service name reported to PAM is pgbouncer. pam is not supported in the HBA configuration file.


HBA configuration file to use when auth_type is hba.

Default: not set


The name of the file to load user names and passwords from. See the section called “Authentication File Format” for details.

Most authentication types (see auth_type) require that either auth_file or auth_user be set; otherwise there would be no users defined.

Default: not set


If auth_user is set, then any user not specified in auth_file will be queried through the auth_query query from pg_shadow in the database, using auth_user. The password of auth_user will be taken from auth_file. (If auth_user does not require a password, then it does not need to be defined in auth_file.)

Direct access to pg_shadow requires admin rights. It's preferable to use a non-superuser that calls a SECURITY DEFINER function instead.

Default: not set


Query to load user's password from database.

Direct access to pg_shadow requires admin rights. It's preferable to use a non-superuser that calls a SECURITY DEFINER function instead.

Note that the query is run inside the target database. So if a function is used, it needs to be installed into each database.

Default: SELECT usename, passwd FROM pg_shadow WHERE usename=$1

Log Settings


Toggles syslog on/off. On Windows, the event log is used instead.

Default: 0


Under what name to send logs to syslog.

Default: pgbouncer (program name)


Under what facility to send logs to syslog. Possibilities: auth, authpriv, daemon, user, local0-7.

Default: daemon


Log successful logins.

Default: 1


Log disconnections with reasons.

Default: 1


Log error messages the pooler sends to clients.

Default: 1


Write aggregated statistics into the log, every stats_period. This can be disabled if external monitoring tools are used to grab the same data from SHOW commands.

Default: 1


Increase verbosity. Mirrors the -v switch on the command line. For example, using -v -v on the command line is the same as verbose=2.

Default: 0

Console Access Control


Comma-separated list of database users that are allowed to connect and run all commands on the console. Ignored when auth_type is any, in which case any user name is allowed in as admin.

Default: empty


Comma-separated list of database users that are allowed to connect and run read-only queries on the console. That means all SHOW commands except SHOW FDS.

Default: empty

Connection Sanity Checks, Timeouts


Query sent to server on connection release, before making it available to other clients. At that moment no transaction is in progress, so the value should not include ABORT or ROLLBACK.

The query is supposed to clean any changes made to the database session so that the next client gets the connection in a well-defined state. The default is DISCARD ALL, which cleans everything, but that leaves the next client no pre-cached state. It can be made lighter, e.g. DEALLOCATE ALL to just drop prepared statements, if the application does not break when some state is kept around.

When transaction pooling is used, the server_reset_query is not used, because in that mode, clients must not use any session-based features, since each transaction ends up in a different connection and thus gets a different session state.



Whether server_reset_query should be run in all pooling modes. When this setting is off (default), the server_reset_query will be run only in pools that are in sessions-pooling mode. Connections in transaction-pooling mode should not have any need for a reset query.

This setting is for working around broken setups that run applications that use session features over a transaction-pooled pgbouncer. It changes non-deterministic breakage to deterministic breakage: clients always lose their state after each transaction.

Default: 0


How long to keep released connections available for immediate re-use, without running server_check_query on it. If 0 then the query is always run.

Default: 30.0


Simple do-nothing query to check if the server connection is alive.

If an empty string, then sanity checking is disabled.

Default: select 1


Disconnect a server in session pooling mode immediately or after the end of the current transaction if it is in close_needed mode (set by RECONNECT, RELOAD that changes connection settings, or DNS change), rather than waiting for the session end. In statement or transaction pooling mode, this has no effect since that is the default behavior there.

If because of this setting a server connection is closed before the end of the client session, the client connection is also closed. This ensures that the client notices that the session has been interrupted.

This setting makes connection configuration changes take effect sooner if session pooling and long-running sessions are used. The downside is that client sessions are liable to be interrupted by a configuration change, so client applications will need logic to reconnect and reestablish session state. But note that no transactions will be lost, because running transactions are not interrupted, only idle sessions.

Default: 0


The pooler will close an unused (not currently linked to any client connection) server connection that has been connected longer than this. Setting it to 0 means the connection is to be used only once, then closed. [seconds]

Default: 3600.0


If a server connection has been idle more than this many seconds it will be closed. If 0 then timeout is disabled. [seconds]

Default: 600.0


If connection and login don't finish in this amount of time, the connection will be closed. [seconds]

Default: 15.0


If login to the server failed, because of failure to connect or from authentication, the pooler waits this much before retrying to connect. During the waiting interval, new clients trying to connect to the failing server will get an error immediately without another connection attempt. [seconds]

The purpose of this behavior is that clients don't unnecessarily queue up waiting for a server connection to become available if the server is not working. However, it also means that if a server is momentarily failing, for example during a restart or if the configuration was erroneous, then it will take at least this long until the pooler will consider connecting to it again. Planned events such as restarts should normally be managed using the PAUSE command to avoid this.

Default: 15.0


If a client connects but does not manage to log in in this amount of time, it will be disconnected. Mainly needed to avoid dead connections stalling SUSPEND and thus online restart. [seconds]

Default: 60.0


If the automatically created (via "*") database pools have been unused this many seconds, they are freed. The negative aspect of that is that their statistics are also forgotten. [seconds]

Default: 3600.0


How long DNS lookups can be cached. The actual DNS TTL is ignored. [seconds]

Default: 15.0


How long DNS errors and NXDOMAIN DNS lookups can be cached. [seconds]

Default: 15.0


Period to check if a zone serial has changed.

pgbouncer can collect DNS zones from host names (everything after first dot) and then periodically check if the zone serial changes. If it notices changes, all host names under that zone are looked up again. If any host IP changes, its connections are invalidated.

Default: 0.0 (disabled)


The location of a custom resolv.conf file. This is to allow specifying custom DNS servers and perhaps other name resolution options, independent of the global operating system configuration.

The parsing of the file is done by the DNS backend library, not pgbouncer, so see the library's documentation for details on allowed syntax and directives.

Default: empty (use operating system defaults)

TLS Settings


TLS mode to use for connections from clients. TLS connections are disabled by default. When enabled, client_tls_key_file and client_tls_cert_file must be also configured to set up the key and certificate pgbouncer uses to accept client connections.


Plain TCP. If client requests TLS, it's ignored. Default.


If client requests TLS, it is used. If not, plain TCP is used. If the client presents a client certificate, it is not validated.


Same as allow.


The client must use TLS. If not, the client connection is rejected. If the client presents a client certificate, it is not validated.


Client must use TLS with valid client certificate.


Same as verify-ca.


Private key for pgbouncer to accept client connections.

Default: not set


Certificate for private key. Clients can validate it.

Default: not set


Root certificate file to validate client certificates.

Default: not set


Which TLS protocol versions are allowed. Allowed values: tlsv1.0, tlsv1.1, tlsv1.2, tlsv1.3. Shortcuts: all (tlsv1.0,tlsv1.1,tlsv1.2,tlsv1.3), secure (tlsv1.2,tlsv1.3), legacy (all).

Default: secure


Allowed TLS ciphers, in OpenSSL syntax. Shortcuts: default/secure, compat/legacy, insecure/all, normal, fast.

Only connections using TLS version 1.2 and lower are affected. There is currently no setting that controls the cipher choices used by TLS version 1.3 connections.

Default: fast


Elliptic Curve name to use for ECDH key exchanges.

Allowed values: none (DH is disabled), auto (256-bit ECDH), curve name.

Default: auto


DHE key exchange type.

Allowed values: none (DH is disabled), auto (2048-bit DH), legacy (1024-bit DH).

Default: auto


TLS mode to use for connections to Postgres Pro servers. TLS connections are disabled by default.


Plain TCP. TLS is not even requested from the server. Default.


TLS connection is always requested first from Postgres Pro. If refused, the connection will be established over plain TCP. Server certificate is not validated.


Connection must go over TLS. If server rejects it, plain TCP is not attempted. Server certificate is not validated.


Connection must go over TLS and server certificate must be valid according to server_tls_ca_file. Server host name is not checked against certificate.


Connection must go over TLS and server certificate must be valid according to server_tls_ca_file. Server host name must match certificate information.


Root certificate file to validate Postgres Pro server certificates.

Default: not set


Private key for pgbouncer to authenticate against Postgres Pro server.

Default: not set


Certificate for private key. Postgres Pro server can validate it.

Default: not set


Which TLS protocol versions are allowed. Allowed values: tlsv1.0, tlsv1.1, tlsv1.2, tlsv1.3. Shortcuts: all (tlsv1.0,tlsv1.1,tlsv1.2,tlsv1.3), secure (tlsv1.2,tlsv1.3), legacy (all).

Default: secure


Allowed TLS ciphers, in OpenSSL syntax. Shortcuts: default/secure, compat/legacy, insecure/all, normal, fast.

Only connections using TLS version 1.2 and lower are affected. There is currently no setting that controls the cipher choices used by TLS version 1.3 connections.

Default: fast

Dangerous Timeouts

Setting the following timeouts can cause unexpected errors.


Queries running longer than that are canceled. This should be used only with a slightly smaller server-side statement_timeout, to apply only for network problems. [seconds]

Default: 0.0 (disabled)


Maximum time queries are allowed to spend waiting for execution. If the query is not assigned to a server during that time, the client is disconnected. The 0 value disables this parameter. If this is disabled, clients will be queued indefinitely. [seconds]

This setting is used to prevent unresponsive servers from grabbing up connections. It also helps when the server is down or rejects connections for any reason.

Default: 120


Client connections idling longer than this many seconds are closed. This should be larger than the client-side connection lifetime settings, and only used for network problems. [seconds]

Default: 0.0 (disabled)


If a client has been in the idle in transaction state longer, it will be disconnected. [seconds]

Default: 0.0 (disabled)


How long to wait for buffer flush during SUSPEND or reboot (-R). A connection is dropped if the flush does not succeed. [seconds]

Default: 10

Low-Level Network Settings


Internal buffer size for packets. Affects size of TCP packets sent and general memory usage. Actual libpq packets can be larger than this, so no need to set it large.

Default: 4096


Maximum size for Postgres Pro packets that pgbouncer allows through. One packet is either one query or one result set row. The full result set can be larger.

Default: 2147483647


The value of the backlog argument for listen(). Determines how many new unanswered connection attempts are kept in the queue. When the queue is full, further new connections are dropped.

Default: 128


How many times to process data on one connection, before proceeding. Without this limit, one connection with a big result set can stall pgbouncer for a long time. One loop processes one pkt_buf amount of data. 0 means no limit.

Default: 5


Specifies whether to set the socket option SO_REUSEPORT on TCP listening sockets. On some operating systems, this allows running multiple pgbouncer instances on the same host listening on the same port and having the kernel distribute the connections automatically. This option is a way to get pgbouncer to use more CPU cores. (pgbouncer is single-threaded and uses one CPU core per instance.)

This setting has the desired effect on Linux. On systems that don't support the socket option at all, turning this setting on will result in an error.

Each pgbouncer instance on the same host needs different settings for at least unix_socket_dir and pidfile, as well as logfile if that is used. Also note that if you make use of this option, you can no longer connect to a specific pgbouncer instance via TCP/IP, which might have implications for monitoring and metrics collection.

Default: 0


Sets the TCP_DEFER_ACCEPT socket option; see man 7 tcp for details. (This is a Boolean option: 1 means enabled. The actual value set if enabled is currently hardcoded to 45 seconds.)

This is currently only supported on Linux.

Default: 1 on Linux, otherwise 0


Default: not set


Turns on basic keepalive with OS defaults.

On Linux, the system defaults are tcp_keepidle=7200, tcp_keepintvl=75, tcp_keepcnt=9. They are probably similar on other operating systems.

Default: 1


Default: not set


Default: not set


Default: not set


Sets the TCP_USER_TIMEOUT socket option. This specifies the maximum amount of time in milliseconds that transmitted data may remain unacknowledged before the TCP connection is forcibly closed. If set to 0, then operating system's default is used.

This is currently only supported on Linux.

Default: 0

Section [databases]

The section [databases] defines the names of the databases that clients of pgbouncer can connect to and specifies where those connections will be routed. The section contains key=value lines like

dbname = connection string

where the key will be taken as a database name and the value as a connection string, consisting of key=value pairs of connection parameters, described below (similar to libpq, but the actual libpq is not used and the set of available features is different).


foodb = port=5432
bardb = host=localhost dbname=bazdb

The database name can contain characters _0-9A-Za-z without quoting. Names that contain other chars need to be quoted with standard SQL ident quoting: double quotes where "" is taken as single quote.

The database name pgbouncer is reserved for the admin console and cannot be used as a key here.

* acts as fallback database: if the exact name does not exist, its value is taken as connection string for the requested database. For example, if there is the following entry (and no other overriding entries):

* = host=foo

In this case, a connection to pgbouncer specifying a database bar will effectively behave as if the following entry exists (taking advantage of the default for dbname being the client-side database name):

bar = host=foo dbname=bar

Such automatically created database entries are cleaned up if they stay idle longer than the time specified by the autodb_idle_timeout parameter.


Destination database name.

Default: same as client-side database name


Host name or IP address to connect to. Host names are resolved at connection time, the result is cached per dns_max_ttl parameter. When a host name's resolution changes, existing server connections are automatically closed when they are released (according to the pooling mode), and new server connections immediately use the new resolution. If DNS returns several results, they are used in a round-robin manner.

If the value begins with /, then a Unix socket in the file-system namespace is used. If the value begins with @, then a Unix socket in the abstract namespace is used.

A comma-separated list of host names or addresses can be specified. In that case, connections are made in a round-robin manner. (If a host list contains host names that in turn resolve via DNS to multiple addresses, the round-robin systems operate independently. This is an implementation dependency that is subject to change.) Note that in a list, all hosts must be available at all times: there are no mechanisms to skip unreachable hosts or to select only available hosts from a list or similar. (This is different from what a host list in libpq means.) Also note that this only affects how the destinations of new connections are chosen. See also the setting server_round_robin for how clients are assigned to already established server connections.



Default: not set, meaning to use a Unix socket


Default: 5432


If user= is set, all connections to the destination database will be done with the specified user, meaning that there will be only one pool for this database.

Otherwise pgbouncer logs into the destination database with the client user name, meaning that there will be one pool per user.


If no password is specified here, the password from the auth_file or auth_query will be used.


Override of the global auth_user setting, if specified.


Set the maximum size of pools for this database. If not set, the default_pool_size is used.


Set the minimum pool size for this database. If not set, the global min_pool_size is used.


Set additional connections for this database. If not set, reserve_pool_size is used.


Query to be executed after a connection is established, but before allowing the connection to be used by any clients. If the query raises errors, they are logged but ignored otherwise.


Set the pool mode specific to this database. If not set, the default pool_mode is used.


Configure a database-wide maximum (i.e. all pools within the database will not have more than this many server connections).


Ask specific client_encoding from server.


Ask specific datestyle from server.


Ask specific timezone from server.

Section [users]

This section contains key=value lines like

user1 = settings

where the key will be taken as a user name and the value as a list of configuration settings specific for this user.


user1 = pool_mode=session

Only a few settings are available here.


Set the pool mode to be used for all connections from this user. If not set, the database or default pool_mode is used.


Configure a maximum for the user (i.e. all pools with the user will not have more than this many server connections).

Include Directive

The pgbouncer configuration file can contain include directives, which specify another configuration file to read and process. This allows splitting the configuration file into physically separate parts. The include directives look like this:

%include filename

If the filename is not an absolute path, it is taken as relative to the current working directory.

Authentication File Format

This section describes the format of the file specified by the auth_file setting. It is a text file in the following format:

"username1" "password" ...
"username2" "md5abcdef012342345" ...
"username2" "SCRAM-SHA-256$iterations:salt$storedkey:serverkey"

There should be at least two fields, surrounded by double quotes. The first field is the user name and the second is either a plain-text, a MD5-hashed password, or a SCRAM secret. pgbouncer ignores the rest of the line. Double quotes in a field value can be escaped by writing two double quotes.

Postgres Pro MD5-hashed password format:

"md5" + md5(password + username)

So user admin with password 1234 will have MD5-hashed password md545f2603610af569b6155c45067268c6b.

Postgres Pro SCRAM secret format:


The passwords or secrets stored in the authentication file serve two purposes. First, they are used to verify the passwords of incoming client connections, if a password-based authentication method is configured. Second, they are used as the passwords for outgoing connections to the backend server, if the backend server requires password-based authentication (unless the password is specified directly in the database's connection string). The latter works if the password is stored in plain text or MD5-hashed. SCRAM secrets can only be used for logging into a server if the client authentication also uses SCRAM, the pgbouncer database definition does not specify a user name, and the SCRAM secrets are identical in pgbouncer and the Postgres Pro server (same salt and iterations, not merely the same password). This is due to an inherent security property of SCRAM: the stored SCRAM secret cannot by itself be used for deriving login credentials.

The authentication file can be written by hand, but it's also useful to generate it from some other list of users and passwords. See ./etc/ for a sample script to generate the authentication file from the pg_shadow system table.

Alternatively, use auth_query instead of auth_file to avoid having to maintain a separate authentication file.

HBA File Format

The location of the HBA file is specified by the setting auth_hba_file. It is only used if auth_type is set to hba.

The file follows the format of the Postgres Pro pg_hba.conf file described in Section 19.1.

  • Supported record types: local, host, hostssl, hostnossl.

  • Database field: Supports all, sameuser, @file, multiple names. Not supported: replication, samerole, samegroup.

  • User name field: Supports all, @file, multiple names. Not supported: +groupname.

  • Address field: Supports IPv4, IPv6. Not supported: DNS names, domain prefixes.

  • Auth-method field: Only methods supported by pgbouncer's auth_type are supported, plus peer and reject, but except any and pam, which only work globally. User name map (map=) parameter is not supported.


Small example configuration:

template1 = host=localhost dbname=template1 auth_user=someuser

pool_mode = session
listen_port = 6432
listen_addr = localhost
auth_type = md5
auth_file = users.txt
logfile = pgbouncer.log
pidfile =
admin_users = someuser
stats_users = stat_collector

Database examples:


; foodb over Unix socket
foodb =

; redirect bardb to bazdb on localhost
bardb = host=localhost dbname=bazdb

; access to destination database will go with single user
forcedb = host=localhost port=300 user=baz password=foo client_encoding=UNICODE datestyle=ISO

Example of a secure function for auth_query:

CREATE OR REPLACE FUNCTION pgbouncer.user_lookup(in i_username text, out uname text, out phash text)
RETURNS record AS $$
    SELECT usename, passwd FROM pg_catalog.pg_shadow
    WHERE usename = i_username INTO uname, phash;
REVOKE ALL ON FUNCTION pgbouncer.user_lookup(text) FROM public, pgbouncer;
GRANT EXECUTE ON FUNCTION pgbouncer.user_lookup(text) TO pgbouncer;