pgbouncer
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pgbouncer

pgbouncer — a Postgres Pro connection pooler

Synopsis

On Linux systems:

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

pgbouncer -V | -h

On Windows systems:

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

Description

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: 

    [databases]
template1 = host=127.0.0.1 port=5432 dbname=template1

[pgbouncer]
listen_port = 6543
listen_addr = 127.0.0.1
auth_type = md5
auth_file = userlist.txt
logfile = pgbouncer.log
pidfile = pgbouncer.pid
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

    Note

    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 6543 -U someuser template1

  5. Manage pgbouncer by connecting to the special administration database pgbouncer and issuing SHOW HELP; to begin: 

    $ psql -p 6543 -U someuser pgbouncer
pgbouncer=# SHOW HELP;
NOTICE:  Console usage
DETAIL:
  SHOW [HELP|CONFIG|DATABASES|FDS|POOLS|CLIENTS|SERVERS|SOCKETS|LISTS|VERSION|...]
  SET key = arg
  RELOAD
  PAUSE
  SUSPEND
  RESUME
  SHUTDOWN
  [...]

  6. If you made changes to the pgbouncer.ini file, you can reload it with: 

    pgbouncer=# RELOAD;

Options

-d

Run in the background. Without it, the process will run in the foreground.

Note

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

-R

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.

Note

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

Switch to the given user on startup.

-v

Increase verbosity. Can be used multiple times.

-q

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

-V

Show version.

-h

Show short help.

--regservice

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

--unregservice

Win32: Unregister Windows service.

Admin Console

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

$ psql -p 6543 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.

Show Commands

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

SHOW STATS

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

database

Statistics are presented per database.

total_xact_count

Total number of SQL transactions pooled by pgbouncer.

total_query_count

Total number of SQL queries pooled by pgbouncer.

total_received

Total volume in bytes of network traffic received by pgbouncer.

total_sent

Total volume in bytes of network traffic sent by pgbouncer.

total_xact_time

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

total_query_time

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

total_wait_time

Time spent by clients waiting for a server, in microseconds.

avg_xact_count

Average transactions per second in last stat period.

avg_query_count

Average queries per second in last stat period.

avg_recv

Average received (from clients) bytes per second.

avg_sent

Average sent (to clients) bytes per second.

avg_xact_time

Average transaction duration, in microseconds.

avg_query_time

Average query duration, in microseconds.

avg_wait_time

Time spent by clients waiting for a server, in microseconds (average per second).

SHOW STATS_TOTALS

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

SHOW STATS_AVERAGES

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

SHOW TOTALS

Like SHOW STATS but aggregated across all databases.

SHOW SERVERS

type

S, for server.

user

User name pgbouncer uses to connect to server.

database

Database name.

state

State of the pgbouncer server connection, one of active, used or idle.

addr

IP address of Postgres Pro server.

port

Port of Postgres Pro server.

local_addr

Connection start address on local machine.

local_port

Connection start port on local machine.

connect_time

When the connection was made.

request_time

When last request was issued.

wait

Current waiting time in seconds.

wait_us

Microsecond part of the current waiting time.

close_needed

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.

ptr

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

link

Address of client connection the server is paired with.

remote_pid

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.

tls

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

SHOW CLIENTS

type

C, for client.

user

Client connected user.

database

Database name.

state

State of the client connection, one of active, used, waiting or idle.

addr

IP address of client.

port

Port client is connected to.

local_addr

Connection end address on local machine.

local_port

Connection end port on local machine.

connect_time

Timestamp of connect time.

request_time

Timestamp of latest client request.

wait

Current waiting time in seconds.

wait_us

Microsecond part of the current waiting time.

close_needed

Not used for clients.

ptr

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

link

Address of server connection the client is paired with.

remote_pid

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

tls

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

SHOW POOLS

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

database

Database name.

user

User name.

cl_active

Client connections that are linked to server connection and can process queries.

cl_waiting

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

sv_active

Server connections that linked to a client.

sv_idle

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

sv_used

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.

sv_tested

Server connections that are currently running either server_reset_query or server_check_query.

sv_login

Server connections currently in the process of logging in.

maxwait

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.

maxwait_us

Microsecond part of the maximum waiting time.

pool_mode

The pooling mode in use.

SHOW LISTS

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

databases

Count of databases.

users

Count of users.

pools

Count of pools.

free_clients

Count of free clients.

used_clients

Count of used clients.

login_clients

Count of clients in login state.

free_servers

Count of free servers.

used_servers

Count of used servers.

dns_names

Count of DNS names in the cache.

dns_zones

Count of DNS zones in the cache.

dns_queries

Count of in-flight DNS queries.

dns_pending

Not used.

SHOW USERS

name

The user name.

pool_mode

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

SHOW DATABASES

name

Name of configured database entry.

host

Host pgbouncer connects to.

port

Port pgbouncer connects to.

database

Actual database name pgbouncer connects to.

force_user

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.

pool_size

Maximum number of server connections.

reserve_pool

Maximum number of additional connections for this database.

pool_mode

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

max_connections

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

current_connections

Current number of connections for this database.

paused

1 if this database is currently paused, else 0.

disabled

1 if this database is currently disabled, else 0.

SHOW FDS

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.

Note

This does not work on Windows systems.

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

fd

File descriptor numeric value.

task

One of pooler, client or server.

user

User of the connection using the FD.

database

Database of the connection using the FD.

addr

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

port

Port used by the connection using the FD.

cancel

Cancel key for this connection.

link

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

SHOW SOCKETS, SHOW ACTIVE_SOCKETS

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 CONFIG

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

key

Configuration variable name.

value

Configuration value.

changeable

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.

SHOW MEM

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

SHOW DNS_HOSTS

Show host names in DNS cache.

hostname

Host name.

ttl

How many seconds until next lookup.

addrs

Comma separated list of addresses.

SHOW DNS_ZONES

Show DNS zones in cache.

zonename

Zone name.

serial

Current serial.

count

Host names belonging to this zone.

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.

DISABLE db

Reject all new client connections on the given database.

ENABLE db

Allow new client connections after a previous DISABLE command.

RECONNECT db

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.

KILL db

Immediately drop all client and server connections on given database.

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

SUSPEND

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 [db]

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

SHUTDOWN

The pgbouncer process will exit.

RELOAD

The pgbouncer process will reload its configuration file and update changeable settings.

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_CLOSE [db]

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.)

Signals

SIGHUP

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

SIGINT

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

SIGTERM

Immediate shutdown. Same as issuing SHUTDOWN on the console.

SIGUSR1

Same as issuing PAUSE on the console.

SIGUSR2

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 when they appear later in the line.

Generic Settings

logfile

Specifies log file. Log file is kept open so after rotation kill -HUP or on console RELOAD; should be done. Note: On Windows systems, the service must be stopped and started.

Default: not set

pidfile

Specifies the PID file. Without a pidfile, daemonization is not allowed.

Default: not set

listen_addr

Specifies list 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 allowed.

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

Default: not set

listen_port

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

Default: 6432

unix_socket_dir

Specifies location for Unix sockets. Applies to both listening socket and server connections. If set to an empty string, Unix sockets are disabled. Required for online reboot (-R) to work. Note: Not supported on Windows systems.

Default: /tmp

unix_socket_mode

File system mode for Unix socket.

Default: 0777

unix_socket_group

Group name to use for Unix socket.

Default: not set

user

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 given user.

Note: Not supported on Windows systems.

Default: not set

auth_file

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

Default: not set

auth_hba_file

HBA configuration file to use when auth_type is hba. Supported from version 1.7 onwards.

Default: not set

auth_type

How to authenticate users.

pam

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

hba

Actual authentication type is loaded from auth_hba_file. This allows different authentication methods different access paths. Example: connection over Unix socket uses peer authentication method, connection over TCP must use TLS. Supported from version 1.7 onwards.

cert

Client must connect over TLS connection with valid client certificate. Username is then taken from CommonName field from certificate.

md5

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

scram-sha-256

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.

plain

Clear-text password is sent over wire. Deprecated.

trust

No authentication is done. Username must still exist in auth_file.

any

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

auth_query

Query to load user's password from database.

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

Note that the query is run inside 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

auth_user

If auth_user is set, any user not specified in auth_file will be queried through the auth_query query from pg_shadow in the database using auth_user. auth_user's password will be taken from auth_file.

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

Default: not set

pool_mode

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

session

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

transaction

Server is released back to pool after transaction finishes.

statement

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

max_client_conn

Maximum number of client connections allowed. When increased, the file descriptor limits should also be increased. Note that actual number of file descriptors used is more than max_client_conn. If each user connects under its own username to server, theoretical maximum used is: 

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

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

max_client_conn + (max pool_size * total databases)

The theoretical maximum should be never reached, unless somebody deliberately crafts 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

default_pool_size

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

Default: 20

min_pool_size

Add more server connections to pool if below this number. Improves behavior when usual load suddenly comes back after a period of total inactivity.

Default: 0 (disabled)

reserve_pool_size

How many additional connections to allow to a pool. The 0 value disables this parameter.

Default: 0 (disabled)

reserve_pool_timeout

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

Default: 5.0

max_db_connections

Do not allow more than this many connections per-database (regardless of pool — i.e. user). It should be noted 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: unlimited

max_user_connections

Do not allow more than this many connections per-user (regardless of pool — i.e. user). It should be noted 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.

server_round_robin

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 TCP round-robin behind a database IP, then it is better if pgbouncer also uses connections in that manner, thus achieving uniform load.

Default: 0

ignore_startup_parameters

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 admin and it can ignore them.

Default: empty

disable_pqexec

Disable Simple Query protocol (PQexec). Unlike 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 Extended Query protocol will stay working.

Default: 0

application_name_add_host

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 on start of connection, if application_name is later changed with SET, pgbouncer does not change it again.

Default: 0

conffile

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

Default: file from command line.

service_name

Used on win32 service registration.

Default: pgbouncer

job_name

Alias for service_name.

stats_period

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

Log Settings

syslog

Toggles syslog on/off. On Windows systems, eventlog is used instead.

Default: 0

syslog_ident

Under what name to send logs to syslog.

Default: pgbouncer (program name)

syslog_facility

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

Default: daemon

log_connections

Log successful logins.

Default: 1

log_disconnections

Log disconnections with reasons.

Default: 1

log_pooler_errors

Log error messages pooler sends to clients.

Default: 1

stats_period

Period for writing aggregated stats into log.

Default: 60

log_stats

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

verbose

Increase verbosity. Mirrors "-v" switch on command line. Using "-v -v" on command line is same as verbose=2 in configuration file.

Default: 0

Console Access Control

admin_users

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

Default: empty

stats_users

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

Default: empty.

Connection Sanity Checks, Timeouts

server_reset_query

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

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

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

Default: DISCARD ALL

server_reset_query_always

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 reset query.

It is workaround for broken setups that run apps that use session features over transaction-pooled pgbouncer. It changes non-deterministic breakage to deterministic breakage — client always lose their state after each transaction.

Default: 0

server_check_delay

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

Default: 30.0

server_check_query

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

If an empty string, then sanity checking is disabled.

Default: SELECT 1;

server_fast_close

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

server_lifetime

The pooler will close an unused 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

server_idle_timeout

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

Default: 600.0

server_connect_timeout

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

Default: 15.0

server_login_retry

If login failed, because of failure from connect() or authentication that pooler waits this much before retrying to connect. [seconds]

Default: 15.0

client_login_timeout

If a client connects but does not manage to login 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

autodb_idle_timeout

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

dns_max_ttl

How long the DNS lookups can be cached. If a DNS lookup returns several answers, pgbouncer will robin-between them in the meantime. Actual DNS TTL is ignored. [seconds]

Default: 15.0

dns_nxdomain_ttl

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

Default: 15.0

dns_zone_check_period

Period to check if zone serial has changed.

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

Works only with UDNS and c-ares backends (--with-udns or --with-cares to configure).

Default: 0.0 (disabled)

TLS Settings

client_tls_sslmode

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 key and cert pgbouncer uses to accept client connections.

disable

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

allow

If client requests TLS, it is used. If not, plain TCP is used. If client uses client-certificate, it is not validated.

prefer

Same as allow.

require

Client must use TLS. If not, client connection is rejected. If client uses client-certificate, it is not validated.

verify-ca

Client must use TLS with valid client certificate.

verify-full

Same as verify-ca.

client_tls_key_file

Private key for pgbouncer to accept client connections.

Default: not set.

client_tls_cert_file

Certificate for private key. Clients can validate it.

Default: not set.

client_tls_ca_file

Root certificate file to validate client certificates.

Default: unset.

client_tls_protocols

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: all

client_tls_ciphers

Default: fast

client_tls_ecdhcurve

Elliptic Curve name to use for ECDH key exchanges.

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

Default: auto

client_tls_dheparams

DHE key exchange type.

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

Default: auto

server_tls_sslmode

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

disable

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

prefer

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

require

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

verify-ca

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.

verify-full

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

server_tls_ca_file

Root certificate file to validate Postgres Pro server certificates.

Default: unset.

server_tls_key_file

Private key for pgbouncer to authenticate against Postgres Pro server.

Default: not set.

server_tls_cert_file

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

Default: not set.

server_tls_protocols

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: all

server_tls_ciphers

Default: fast

Dangerous Timeouts

Setting the following timeouts causes unexpected errors.

query_timeout

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

Default: 0.0 (disabled)

query_wait_timeout

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. This is used to prevent unresponsive servers from grabbing up connections. [seconds]

It also helps when server is down or database rejects connections for any reason. If this is disabled, clients will be queued infinitely.

Default: 120

client_idle_timeout

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)

idle_transaction_timeout

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

Default: 0.0 (disabled)

Low-Level Network Settings

pkt_buf

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

max_packet_size

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

Default: 2147483647

listen_backlog

Backlog argument for listen(2). Determines how many new unanswered connection attempts are kept in queue. When queue is full, further new connections are dropped.

Default: 128

sbuf_loopcnt

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

suspend_timeout

How many seconds to wait for buffer flush during SUSPEND or reboot (-R). Connection is dropped if flush does not succeed.

Default: 10

tcp_defer_accept

For details on this and other TCP options, please see man 7 tcp.

Default: 45 on Linux, otherwise 0

tcp_socket_buffer

Default: not set

tcp_keepalive

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

tcp_keepcnt

Default: not set

tcp_keepidle

Default: not set

tcp_keepintvl

Default: not set

Section [databases]

This contains key=value pairs where key will be taken as a database name and value as a libpq connect-string style list of key=value pairs. As actual libpq is not used, not all features from libpq can be used (service=, .pgpass).

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.

"*" acts as fallback database: if the exact name does not exist, its value is taken as connect string for requested database. Such automatically created database entries are cleaned up if they stay idle longer than the time specified in autodb_idle_timeout parameter.

dbname

Destination database name.

Default: same as client-side database name.

host

Host name or IP address to connect to. Host names are resolved at connect 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 round-robin manner.

Default: not set, meaning to use a Unix socket.

port

Default: 5432

user

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 tries to log into the destination database with client username, meaning that there will be one pool per user.

password

The length for password is limited to 160 characters maximum.

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

auth_user

Override of the global auth_user setting, if specified.

pool_size

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

reserve_pool

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

connect_query

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.

pool_mode

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

max_db_connections

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

client_encoding

Ask specific client_encoding from server.

datestyle

Ask specific datestyle from server.

timezone

Ask specific timezone from server.

Section [users]

This contains key=value pairs where the key will be taken as a user name and the value as a libpq connect-string style list of key=value pairs of configuration settings specific for this user. Only a few settings are available here.

pool_mode

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

max_user_connections

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

%include filename

If the file name is not absolute path it is taken as relative to current working directory.

Authentication File Format

pgbouncer needs its own user database. The users are loaded from a text file in 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 username and the second is either a plain-text, a MD5-hidden password, or a SCRAM secret. pgbouncer ignores the rest of the line.

Postgres Pro MD5-hidden password format: 

"md5" + md5(password + username)

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

Postgres Pro SCRAM secret format: 

SCRAM-SHA-256$iterations:salt$storedkey:serverkey

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/mkauth.py for a sample script to generate the authentication file from the pg_shadow system table.

HBA File Format

It follows the format of 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.

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

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

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

Example

Minimal config: 

[databases]
template1 = host=127.0.0.1 dbname=template1 auth_user=someuser

[pgbouncer]
pool_mode = session
listen_port = 6543
listen_addr = 127.0.0.1
auth_type = md5
auth_file = users.txt
logfile = pgbouncer.log
pidfile = pgbouncer.pid
admin_users = someuser
stats_users = stat_collector

Database defaults: 

[databases]

; foodb over Unix socket
foodb =

; redirect bardb to bazdb on localhost
bardb = host=127.0.0.1 dbname=bazdb

; access to destination database will go with single user
forcedb = host=127.0.0.1 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 $$
BEGIN
    SELECT usename, passwd FROM pg_catalog.pg_shadow
    WHERE usename = i_username INTO uname, phash;
    RETURN;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;
REVOKE ALL ON FUNCTION pgbouncer.user_lookup(text) FROM public, pgbouncer;
GRANT EXECUTE ON FUNCTION pgbouncer.user_lookup(text) TO pgbouncer;
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