Provided by: pgbouncer_1.23.1-1_amd64 
NAME
pgbouncer.ini - configuration file for pgbouncer
DESCRIPTION
The configuration file is in “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
logfile
Specifies the log file. For daemonization (-d), either this or syslog need 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
pidfile
Specifies the PID file. Without pidfile set, daemonization (-d) is not allowed.
Default: not set
listen_addr
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
listen_port
Which port to listen on. Applies to both TCP and Unix sockets.
Default: 6432
unix_socket_dir
Specifies the location for Unix sockets. Applies to both the listening socket and to
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)
unix_socket_mode
File system mode for Unix socket. Ignored for sockets in the abstract namespace. Not
supported on Windows.
Default: 0777
unix_socket_group
Group name to use for Unix socket. Ignored for sockets in the abstract namespace. Not
supported on Windows.
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 the given user. Not supported on Windows.
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. Transactions spanning
multiple statements are disallowed in this mode.
max_client_conn
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 user name 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
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 the
normal load suddenly comes back after a period of total inactivity. The value is
effectively capped at the pool size.
Only enforced for pools where at least one of the following is true:
• the entry in the [database] section for the pool has a value set for the user key (aka
forced user)
• there is at least one client connected to the pool
Default: 0 (disabled)
reserve_pool_size
How many additional connections to allow to a pool (see reserve_pool_timeout). 0
disables.
Default: 0 (disabled)
reserve_pool_timeout
If a client has not been serviced in this time, use additional connections from the
reserve pool. 0 disables. [seconds]
Default: 5.0
max_db_connections
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 PostgreSQL
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)
max_user_connections
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)
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 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
track_extra_parameters
By default, PgBouncer tracks client_encoding, datestyle, timezone,
standard_conforming_strings and application_name parameters per client. To allow other
parameters to be tracked, they can be specified here, so that PgBouncer knows that they
should be maintained in the client variable cache and restored in the server whenever the
client becomes active.
If you need to specify multiple values, use a comma-separated list (e.g.
default_transaction_read_only, IntervalStyle)
Note: Most parameters cannot be tracked this way. The only parameters that can be tracked
are ones that Postgres reports to the client. Postgres has an official list of parameters
that it reports to the client (https://www.postgresql.org/docs/15/protocol-
flow.html#PROTOCOL-ASYNC). Postgres extensions can change this list though, they can add
parameters themselves that they also report, and they can start reporting already existing
parameters that Postgres does not report. Notably Citus 12.0+ causes Postgres to also
report search_path.
The Postgres protocol allows specifying parameters settings, both directly as a parameter
in the startup packet, or inside the options startup packet
(https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-OPTIONS).
Parameters specified using both of these methods are supported by track_extra_parameters.
However, it’s not possible to include options itself in track_extra_parameters, only the
parameters contained in options.
Default: IntervalStyle
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 others
parameters will raise an error. To allow others 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)
The Postgres protocol allows specifying parameters settings, both directly as a parameter
in the startup packet, or inside the options startup packet
(https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNECT-OPTIONS).
Parameters specified using both of these methods are supported by
ignore_startup_parameters. It’s even possible to include options itself in
track_extra_parameters, which results in any unknown parameters contained inside options
to be ignored.
Default: empty
peer_id
The peer id used to identify this PgBouncer process in a group of PgBouncer processes that
are peered together. The peer_id value should be unique within a group of peered
PgBouncer processes. When set to 0 pgbouncer peering is disabled. See the docs for the
[peers] section for more information. The maximum value that can be used for the peer_id
is 16383.
Default: 0
disable_pqexec
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
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
at the start of a connection. If application_name is later changed with SET, PgBouncer
does not change it again.
Default: 0
conffile
Show location of current config file. Changing it will make PgBouncer use another config
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
max_prepared_statements
When this is set to a non-zero value PgBouncer tracks protocol-level named prepared
statements related commands sent by the client in transaction and statement pooling mode.
PgBouncer makes sure that any statement prepared by a client is available on the backing
server connection. Even when the statement was originally prepared on another server
connection.
PgBouncer internally examines all the queries that are sent by clients as a prepared
statement, and gives each unique query string an internal name with the format
PGBOUNCER_{unique_id}. If the same query string is prepared multiple times (possibly by
different clients), then these queries share the same internal name. PgBouncer only
prepares the statement on the actual PostgreSQL server using the internal name (so not the
name provided by the client). PgBouncer keeps track of the name that the client gave to
each prepared statement. It then rewrites each command that uses a prepared statement to
by replacing the client side name with the the internal name (e.g. replacing
my_prepared_statement with PGBOUNCER_123) before forwarding that command to the server.
More importantly, if the prepared statement that the client wants to execute is not yet
prepared on the server (e.g. because a different server is now assigned to the client than
when the client prepared the statement), then PgBouncer transparently prepares the
statement before executing it.
Note: This tracking and rewriting of prepared statement commands does not work for SQL-
level prepared statement commands, so PREPARE, EXECUTE and DEALLOCATE are forwarded
straight to Postgres. The exception to this rule are the DEALLOCATE ALL and DISCARD ALL
commands, these do work as expected and will clear the prepared statements that PgBouncer
tracked for the client that sends this command.
The actual value of this setting controls the number of prepared statements kept active in
an LRU cache on a single server connection. When the setting is set to 0 prepared
statement support for transaction and statement pooling is disabled. To get the best
performance you should try to make sure that this setting is larger than the amount of
commonly used prepared statements in your application. Keep in mind that the higher this
value, the larger the memory footprint of each PgBouncer connection will be on your
PostgreSQL server, because it will keep more queries prepared on those connections. It
also increases the memory footprint of PgBouncer itself, because it now needs to keep
track of query strings.
The impact on PgBouncer memory usage is not that big though: - Each unique query is stored
once in a global query cache. - Each client connection keeps a buffer that it uses to
rewrite packets. This is, at most, 4 times the size of pkt_buf. This limit is often not
reached though, it only happens when the queries in your prepared statements are between 2
and 4 times the size of pkt_buf.
So if you consider the following as an example scenario: - There are 1000 active clients -
The clients prepare 200 unique queries - The average size of a query is 5kB - pkt_buf
parameter is set to the default of 4096 (4kB)
Then, PgBouncer needs at most the following amount of memory to handle these prepared
statements:
200 x 5kB + 1000 x 4 x 4kB = ~17MB of memory.
Tracking prepared statements does not only come with a memory cost, but also with
increased CPU usage, because PgBouncer needs to inspect and rewrite the queries. Multiple
PgBouncer instances can listen on the same port to use more than one core for processing,
see the documentation for the so_reuseport option for details.
But of course there are also performance benefits to prepared statements. Just as when
connecting to PostgreSQL directly, by preparing a query that is executed many times, it
reduces the total amount of parsing and planning that needs to be done. The way that
PgBouncer tracks prepared statements is especially beneficial to performance when multiple
clients prepare the same queries. Because client connections automatically reuse a
prepared statement on a server connection, even if it was prepared by another client. As
an example, if you have a pool_size of 20 and you have 100 clients that all prepare the
exact same query, then the query is prepared (and thus parsed) only 20 times on the
PostgreSQL server.
The reuse of prepared statements has one downside. If the return or argument types of a
prepared statement changes across executions then PostgreSQL currently throws an error
such as:
ERROR: cached plan must not change result type
You can avoid such errors by not having multiple clients that use the exact same query
string in a prepared statement, but expecting different argument or result types. One of
the most common ways of running into this issue is during a DDL migration where you add a
new column or change a column type on an existing table. In those cases you can run
RECONNECT on the PgBouncer admin console after doing the migration to force a re-prepare
of the query and make the error go away.
Default: 0
AUTHENTICATION SETTINGS
PgBouncer handles its own client authentication and has its own database of users. These
settings control this.
auth_type
How to authenticate users.
cert Client must connect over TLS connection with a valid client certificate. The user
name is then taken from the CommonName field from the certificate.
md5 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.
scram-sha-256
Use password check with SCRAM-SHA-256. auth_file has to contain SCRAM secrets or
plain-text passwords.
plain The clear-text password is sent over the wire. Deprecated.
trust No authentication is done. The user name must still exist in auth_file.
any 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.
hba 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 the peer auth method, connections over TCP must use TLS.
pam PAM 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.
auth_hba_file
HBA configuration file to use when auth_type is hba. See section HBA file format below
about details.
Default: not set
auth_ident_file
Identity map file to use when auth_type is hba and a user map will be defined. See
section Ident map file format below about details.
Default: not set
auth_file
The name of the file to load user names and passwords from. See section Authentication
file format below about details.
Most authentication types (see above) require that either auth_file or auth_user be set;
otherwise there would be no users defined.
Default: not set
auth_user
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 the 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
auth_query
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
auth_dbname
Database name in the [database] section to be used for authentication purposes. This
option can be either global or overridden in the connection string if this parameter is
specified.
LOG SETTINGS
syslog
Toggles syslog on/off. On Windows, the event log 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 the pooler sends to clients.
Default: 1
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 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
admin_users
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
stats_users
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
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 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.
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 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
server_check_delay
How long to keep released connections available for immediate re-use, without running
server_check_query on it. If 0 then the check 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 (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]
This can also be set per database in the [databases] section.
Default: 3600.0
server_idle_timeout
If a server connection has been idle more than this many seconds it will be closed. If 0
then this timeout is disabled. [seconds]
Default: 600.0
server_connect_timeout
If connection and login don’t finish in this amount of time, the connection will be
closed. [seconds]
Default: 15.0
server_login_retry
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
client_login_timeout
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
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 DNS lookups can be cached. The actual DNS TTL is ignored. [seconds]
Default: 15.0
dns_nxdomain_ttl
How long DNS errors and NXDOMAIN DNS lookups can be cached. [seconds]
Default: 15.0
dns_zone_check_period
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.
Works only with c-ares backend (configure option --with-cares).
Default: 0.0 (disabled)
resolv_conf
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.
Requires evdns (>= 2.0.3) or c-ares (>= 1.15.0) backend.
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
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 the key and certificate PgBouncer uses to accept client connections. The most common
certificate file format usable by PgBouncer is pem.
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 the client
presents a client certificate, it is not validated.
prefer Same as allow.
require
Client must use TLS. If not, the client connection is rejected. If the client
presents a 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: not set
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: secure
client_tls_ciphers
Allowed TLS ciphers, in OpenSSL syntax. Shortcuts:
• default/secure/fast/normal (these all use system wide OpenSSL defaults)
• all (enables all ciphers, not recommended)
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: default
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 PostgreSQL servers. The default mode is prefer.
disable
Plain TCP. TLS is not even requested from the server.
allow FIXME: if server rejects plain, try TLS?
prefer TLS connection is always requested first from PostgreSQL. If refused, the
connection will be established over plain TCP. Server certificate is not
validated. Default
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 information.
server_tls_ca_file
Root certificate file to validate PostgreSQL server certificates.
Default: not set
server_tls_key_file
Private key for PgBouncer to authenticate against PostgreSQL server.
Default: not set
server_tls_cert_file
Certificate for private key. PostgreSQL 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: secure
server_tls_ciphers
Allowed TLS ciphers, in OpenSSL syntax. Shortcuts:
• default/secure/fast/normal (these all use system wide OpenSSL defaults)
• all (enables all ciphers, not recommended)
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: default
DANGEROUS TIMEOUTS
Setting the following timeouts can cause unexpected errors.
query_timeout
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)
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. 0 disables. 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: 120.0
cancel_wait_timeout
Maximum time cancellation requests are allowed to spend waiting for execution. If the
cancel request is not assigned to a server during that time, the client is disconnected.
0 disables. If this is disabled, cancel requests will be queued indefinitely. [seconds]
This setting is used to prevent a client locking up when a cancel cannot be forwarded due
to the server being down.
Default: 10.0
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 a client has been in “idle in transaction” state longer, it will be disconnected.
[seconds]
Default: 0.0 (disabled)
suspend_timeout
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
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 PostgreSQL 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
listen_backlog
Backlog argument for listen(2). Determines how many new unanswered connection attempts
are kept in the queue. When the 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
so_reuseport
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.)
The behavior in detail depends on the operating system kernel. As of this writing, this
setting has the desired effect on (sufficiently recent versions of) Linux, DragonFlyBSD,
and FreeBSD. (On FreeBSD, it applies the socket option SO_REUSEPORT_LB instead.) Some
other operating systems support the socket option but it won’t have the desired effect: It
will allow multiple processes to bind to the same port but only one of them will get the
connections. See your operating system’s setsockopt() documentation for details.
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.
To make sure query cancellations keep working, you should set up PgBouncer peering between
the different PgBouncer processes. For details look at docs for the peer_id configuration
option and the peers configuration section. There’s also an example that uses peering and
so_reuseport in the example section of these docs.
Default: 0
tcp_defer_accept
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
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
tcp_user_timeout
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).
Example:
foodb = host=host1.example.com port=5432
bardb = host=localhost dbname=bazdb
The database name can contain characters _0-9A-Za-z without quoting. Names that contain
other characters need to be quoted with standard SQL identifier quoting: double quotes,
with “” for a single instance of a double quote.
The database name “pgbouncer” is reserved for the admin console and cannot be used as a
key here.
“*” acts as a 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 an entry (and no
other overriding entries)
* = host=foo
then a connection to PgBouncer specifying a database “bar” will effectively behave as if
an entry
bar = host=foo dbname=bar
exists (taking advantage of the default for dbname being the client-side database name;
see below).
Such automatically created database entries are cleaned up if they stay idle longer than
the time specified by the 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 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.
Examples:
host=localhost
host=127.0.0.1
host=2001:0db8:85a3:0000:0000:8a2e:0370:7334
host=/var/run/postgresql
host=192.168.0.1,192.168.0.2,192.168.0.3
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 logs into the destination database with the client user name, meaning
that there will be one pool per user.
password
If no password is specified here, the password from the auth_file will be used for the
user specified above. Dynamic forms of password discovery such as auth_query are not
currently supported.
auth_user
Override of the global auth_user setting, if specified.
auth_query
Override of the global auth_query setting, if specified. The entire SQL statement needs
to be enclosed in single quotes.
auth_dbname
Override of the global auth_dbname setting, if specified.
pool_size
Set the maximum size of pools for this database. If not set, the default_pool_size is
used.
min_pool_size
Set the minimum pool size for this database. If not set, the global min_pool_size is
used.
Only enforced if at least one of the following is true:
• this entry in the [database] section has a value set for the user key (aka forced user)
• there is at least one client connected to the pool
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).
server_lifetime
Configure the server_lifetime per database. If not set the database will fall back to the
instance wide configured value for server_lifetime
client_encoding
Ask specific client_encoding from server.
datestyle
Ask specific datestyle from server.
timezone
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 key=value pairs of
configuration settings specific for this user. Example:
user1 = pool_mode=session
Only a few settings are available here.
Note that when auth_file is configured, if a user is defined in this section but not
listed in auth_file, pgBouncer will attempt to use auth_query to find a password for that
user if auth_user is set. If auth_user is not set, pgBouncer will pretend the user exists
and fail to return “no such user” messages to the client, but neither will it accept any
provided password.
pool_size
Set the maximum size of pools for all connections from this user. If not set, the
database or default_pool_size is used.
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).
SECTION [PEERS]
The section [peers] defines the peers that PgBouncer can forward cancellation requests to
and where those cancellation requests will be routed.
PgBouncer processes can be peered together in a group by defining a peer_id value and a
[peers] section in the configs of all the PgBouncer processes. These PgBouncer processes
can then forward cancellations requests to the process that it originated from. This is
needed to make cancellations work when multiple PgBouncer processes (possibly on different
servers) are behind the same TCP load balancer. Cancellation requests are sent over
different TCP connections than the query they are cancelling, so a TCP load balancer might
send the cancellation request connection to a different process than the one that it was
meant for. By peering them these cancellation requests eventually end up at the right
process. A more in-depth explanation is provided in this recording of a conference talk
(https://www.youtube.com/watch?v=M585FfbboNA).
The section contains key=value lines like
peer_id = connection string
Where the key will be taken as a peer_id 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). Example:
1 = host=host1.example.com
2 = host=/tmp/pgbouncer-2 port=5555
Note 1: For peering to work, the peer_id of each PgBouncer process in the group must be
unique within the peered group. And the [peers] section should contain entries for each
of those peer ids. An example can be found in the examples section of these docs. It is
allowed, but not necessary, for the [peers] section to contain the peer_id of the
PgBouncer that the config is for. Such an entry will be ignored, but it is allowed to
config management easy. Because it allows using the exact same [peers] section for
multiple configs.
Note 2: Cross-version peering is supported as long as all peers are on the same side of
the v1.21.0 version boundary. In v1.21.0 some breaking changes were made in how we encode
the cancellation tokens that made them incompatible with the ones created by earlier
versions.
host
Host name or IP address to connect to. Host names are resolved at connection time, the
result is cached per dns_max_ttl parameter. If DNS returns several results, they are used
in a round-robin manner. But in general it’s not recommended to use a hostname that
resolves to multiple IPs, because then the cancel request might still be forwarded to the
wrong node and it would need to be forwarded again (which is only allowed up to three
times).
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.
Examples:
host=localhost
host=127.0.0.1
host=2001:0db8:85a3:0000:0000:8a2e:0370:7334
host=/var/run/pgbouncer-1
port
Default: 6432
pool_size
Set the maximum number of cancel requests that can be in flight to the peer at the same
time. It’s quite normal for cancel requests to arrive in bursts, e.g. when the backing
Postgres server slow or down. So it’s important for pool_size to not be so low that it
cannot handle these bursts.
If not set, the default_pool_size is used.
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 file name 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>$<storedkey>:<serverkey>"
There should be at least 2 fields, surrounded by double quotes. The first field is the
user name and the second is either a plain-text, a MD5-hashed password, or a SCRAM secret.
PgBouncer ignores the rest of the line. Double quotes in a field value can be escaped by
writing two double quotes.
PostgreSQL MD5-hashed password format:
"md5" + md5(password + username)
So user admin with password 1234 will have MD5-hashed password
md545f2603610af569b6155c45067268c6b.
PostgreSQL SCRAM secret format:
SCRAM-SHA-256$<iterations>:<salt>$<storedkey>:<serverkey>
See the PostgreSQL documentation and RFC 5803 for details on this.
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).
Limitations
If the password is stored in plain text, it can be used for any password-based
authentication used in the backend server; plain text, MD5 or SCRAM (see
<https://www.postgresql.org/docs/current/auth-password.html> for details).
MD5-hashed passwords can be used if backend server uses MD5 authentication (or specific
users have MD5-hashed passwords).
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 PostgreSQL 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/mkauth.py 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.
Note on managed servers
If the backend server is configured to use SCRAM password authentication PgBouncer cannot
successfully authenticate if it does not know either a) user password in plain text or b)
corresponding SCRAM secret.
Some cloud providers (i.e. AWS RDS) prohibit access to PostgreSQL sensitive system tables
for fetching passwords. Even for the most privileged user (i.e. member of rds_superuser)
the select * from pg_authid; returns the ERROR: permission denied for table pg_authid.
That is a known behaviour (blog (https://aws.amazon.com/blogs/database/best-practices-for-
migrating-postgresql-databases-to-amazon-rds-and-amazon-aurora/)).
Therefore, fetching an existing SCRAM secret once it has been stored in a managed server
is impossible which makes it hard to configure PgBouncer to use the same SCRAM secret.
Nevertheless, SCRAM secret can still be configured and used on both sides using the
following trick:
Generate SCRAM secret for arbitrary password with a tool that is capable of printing out
the secret. For example psql --echo-hidden and the command \password prints out the SCRAM
secret to the console before sending it over to the server.
$ psql --echo-hidden <connection_string>
postgres=# \password <role_name>
Enter new password for user "<role_name>":
Enter it again:
********* QUERY **********
ALTER USER <role_name> PASSWORD 'SCRAM-SHA-256$<iterations>:<salt>$<storedkey>:<serverkey>'
**************************
Note down the SCRAM secret from the QUERY and set it in PgBouncer’s userlist.txt.
If you used a tool other than psql --echo-hidden then you need to set the SCRAM secret
also in the server (you can use alter role <role_name> password '<scram_secret>' for
that).
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 PostgreSQL pg_hba.conf file (see
<https://www.postgresql.org/docs/current/auth-pg-hba-conf.html>).
• Supported record types: local, host, hostssl, hostnossl.
• Database field: Supports all, replication, sameuser, @file, multiple names. Not
supported: samerole, samegroup.
• User name field: Supports all, @file, multiple names. Not supported: +groupname.
• Address field: Supports all, IPv4, IPv6. Not supported: samehost, samenet, 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 supported when auth_type is cert or peer.
IDENT MAP FILE FORMAT
The location of the ident map file is specified by the setting auth_ident_file. It is
only loaded if auth_type is set to hba.
The file format is a simplified variation of the PostgreSQL ident map file (see
<https://www.postgresql.org/docs/current/auth-username-maps.html>).
• Supported lines are only of the form map-name system-username database-username.
• There is no support for including file/directory.
• System-username field: Not supported: regular expressions.
• Database-username field: Supports all or a single postgres user name. Not supported:
+groupname, regular expressions.
EXAMPLES
Small example configuration:
[databases]
template1 = host=localhost dbname=template1 auth_user=someuser
[pgbouncer]
pool_mode = session
listen_port = 6432
listen_addr = localhost
auth_type = md5
auth_file = users.txt
logfile = pgbouncer.log
pidfile = pgbouncer.pid
admin_users = someuser
stats_users = stat_collector
Database examples:
[databases]
; 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 $$
BEGIN
SELECT usename, passwd FROM pg_catalog.pg_shadow
WHERE usename = i_username INTO uname, phash;
RETURN;
END;
$$ 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;
Example configs for 2 peered PgBouncer processes to create a multi-core PgBouncer setup
using so_reuseport. The config for the first process:
[databases]
postgres = host=localhost dbname=postgres
[peers]
1 = host=/tmp/pgbouncer1
2 = host=/tmp/pgbouncer2
[pgbouncer]
listen_addr=127.0.0.1
auth_file=auth_file.conf
so_reuseport=1
unix_socket_dir=/tmp/pgbouncer1
peer_id=1
The config for the second process:
[databases]
postgres = host=localhost dbname=postgres
[peers]
1 = host=/tmp/pgbouncer1
2 = host=/tmp/pgbouncer2
[pgbouncer]
listen_addr=127.0.0.1
auth_file=auth_file.conf
so_reuseport=1
; only unix_socket_dir and peer_id are different
unix_socket_dir=/tmp/pgbouncer2
peer_id=2
SEE ALSO
pgbouncer(1) - man page for general usage, console commands
<https://www.pgbouncer.org/>