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PGBOUNCER.INI(5) Databases PGBOUNCER.INI(5)

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. De-
fault.

transaction
Server is released back to pool after transaction finishes.

statement
Server is released back to pool after query finishes. Transac-
tions 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 theoreti-
cal 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 delib-
erately 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 be-
havior 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 re-
serve_pool_timeout). 0 disables.

Default: 0 (disabled)

reserve_pool_timeout
If a client has not been serviced in this time, use additional connec-
tions from the reserve pool. 0 disables. [seconds]

Default: 5.0

max_db_connections
Do not allow more than this many server connections per database (re-
gardless 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_db_client_connections
Do not allow more than this many client connections to PgBouncer 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 should be set at a number greater than or equal to max_db_connec-
tions. The difference between the two numbers can be thought of as how
many connections to a given database can be in the queue while waiting
for active connections to finish.

This can also be set per database in the [databases] section.

Default: 0 (unlimited)

max_user_connections
Do not allow more than this many server connections per user (regard-
less of database). This considers the PgBouncer user that is associat-
ed with a pool, which is either the user specified for the server con-
nection or in absence of that the user the client has connected as.

This can also be set per user in the [users] section.

Default: 0 (unlimited)

max_user_client_connections
Do not allow more than this many client connections per user (regard-
less of database). This value should be set to a number higher than
max_user_connections. This difference between max_user_connections and
max_user_client_connections can be conceptualized as the number the max
size of the queue for the user.

This can also be set per user in the [users] section.

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 connec-
tions 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 vari-
able cache and restored in the server whenever the client becomes ac-
tive.

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 report-
ing 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 di-
rectly as a parameter in the startup packet, or inside the options
startup packet (https://www.postgresql.org/docs/current/libpq-con-
nect.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_con-
forming_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 di-
rectly as a parameter in the startup packet, or inside the options
startup packet (https://www.postgresql.org/docs/current/libpq-con-
nect.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 re-
sults 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 Pg-
Bouncer 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 al-
lows 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 trans-
action and statement pooling mode. PgBouncer makes sure that any
statement prepared by a client is available on the backing server con-
nection. 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_pre-
pared_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 state-
ments 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 common-
ly 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 av-
erage 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 documenta-
tion for the so_reuseport option for details.

But of course there are also performance benefits to prepared state-
ments. Just as when connecting to PostgreSQL directly, by preparing a
query that is executed many times, it reduces the total amount of pars-
ing and planning that needs to be done. The way that PgBouncer tracks
prepared statements is especially beneficial to performance when multi-
ple clients prepare the same queries. Because client connections auto-
matically 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 Post-
greSQL 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 differ-
ent 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: 200

AUTHENTICATION SETTINGS
PgBouncer handles its own client authentication and has its own data-
base of users. These settings control this.

auth_type
How to authenticate users.

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

md5 Use MD5-based password check. This is the default authentica-
tion 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. Re-
quires 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 ac-
cess 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 op-
tion. 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 sec-
tion 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_authid 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_authid 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_authid 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 func-
tion is used, it needs to be installed into each database.

Default: SELECT rolname, CASE WHEN rolvaliduntil < now() THEN NULL ELSE
rolpassword END FROM pg_authid WHERE rolname=$1 AND rolcanlogin

auth_dbname
Database name in the [database] section to be used for authentication
purposes. This option can be either global or overridden in the con-
nection 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, auth-
priv, 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. 3
is the highest currently-supported verbosity.

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 ex-
cept 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 applica-
tion 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 transac-
tion-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 al-
ways 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 en-
sures 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 con-
nection 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 fail-
ing server will get an error immediately without another connection at-
tempt. [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 erro-
neous, then it will take at least this long until the pooler will con-
sider 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 no-
tices 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, indepen-
dent 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 Pg-
Bouncer, so see the library's documentation for details on allowed syn-
tax and directives.

Default: empty (use operating system defaults)

TLS SETTINGS
If the contents of any of the cert or key files are changed without
changing the actual setting filename in the config, the new file con-
tents will be used for new connections after a RELOAD. Existing con-
nections won't be closed though. If it's necessary for security rea-
sons that all connections start using the new files ASAP, it's advised
to run RECONNECT after the RELOAD.

Changing any TLS settings will trigger a RECONNECT automatically for
security reasons.

client_tls_sslmode
TLS mode to use for connections from clients. TLS connections are dis-
abled by default. When enabled, client_tls_key_file and
client_tls_cert_file must be also configured to set up the key and cer-
tificate 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 validat-
ed.

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 validat-
ed.

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).

Default: secure

client_tls_ciphers
Allowed TLS ciphers, in OpenSSL syntax. Shortcuts:

• default/secure/fast/normal (these all use system wide OpenSSL de-
faults)

• 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 de-
faults)

• 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 on-
ly 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 connec-
tions for any reason.

Default: 120.0

cancel_wait_timeout
Maximum time cancellation requests are allowed to spend waiting for ex-
ecution. 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 can-
not 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 set-
tings, 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 Pg-
Bouncer for a long time. One loop processes one pkt_buf amount of da-
ta. 0 means no limit.

Default: 5

so_reuseport
Specifies whether to set the socket option SO_REUSEPORT on TCP listen-
ing 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 op-
tion 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 re-
cent versions of) Linux, DragonFlyBSD, and FreeBSD. (On FreeBSD, it
applies the socket option SO_REUSEPORT_LB instead.) Some other operat-
ing systems support the socket option but it won't have the desired ef-
fect: It will allow multiple processes to bind to the same port but on-
ly 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 Pg-
Bouncer peering between the different PgBouncer processes. For details
look at docs for the peer_id configuration option and the peers config-
uration 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 unac-
knowledged 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 con-
nection 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 effec-
tively 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 parame-
ter.

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 con-
nection time, the result is cached per dns_max_ttl parameter. When a
host name's resolution changes, existing server connections are auto-
matically 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 name-
space 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 ad-
dresses, the round-robin systems operate independently. This is an im-
plementation 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 connec-
tions 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 dis-
covery 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 de-
fault_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_size
Set additional connections for this database. If not set, the global
reserve_pool_size is used. For backwards compatibilty reasons re-
serve_pool is an alias for this option.

connect_query
Query to be executed after a connection is established, but before al-
lowing 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.

load_balance_hosts
When a comma-separated list is specified in host, load_balance_hosts
controls which entry is chosen for a new connection.

Note: This setting currently only controls the load balancing behaviour
when providing multiple hosts in the connection string, but not when a
single host its DNS record references multiple IP addresses. This is a
missing feature, so in a future release this setting might start to to
control both methods of load balancing.

round-robin
A new connection attempt chooses the next host entry in the
list.

disable
A new connection continues using the same host entry until a
connection fails, after which the next host entry is chosen.

It is recommended to set server_login_retry lower than the default to
ensure fast retries when multiple hosts are available.

Default: round-robin

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

max_db_client_connections
Configure a database-wide client connection maximum. Should be used in
conjunction with max_client_conn to limit the number of connections
that PgBouncer is allowed to accept.

server_lifetime
Configure the server_lifetime per database. If not set the database
will fall back to the instance wide configured value for server_life-
time

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. Ex-
ample:

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.

reserve_pool_size
Set the number of additional connections to allow to a pool for this
user. If not set, the database configuration or the global re-
serve_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 of server connections (i.e. all pools
with the user will not have more than this many server connections).

query_timeout
Set the maximum number of seconds that a user query can run for. If
set this timeout overrides the server level query_timeout described
above.

idle_transaction_timeout
Set the maximum number of seconds that a user can have an idle transac-
tion open. If set this timeout overides the server level idle_transac-
tion_timeout described above.

client_idle_timeout
Set the maximum amount of time in seconds that a client is allowed to
idly connect to the pgbouncer instance. If set this timeout overrides
the server level client_idle_timeout described above.

Please note that this is a potentially dangeous timeout.

max_user_client_connections
Configure a maximum for the user of client connections. This is the
user equivalent ofthe max_client_conn setting.

SECTION [PEERS]
The section [peers] defines the peers that PgBouncer can forward can-
cellation 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 re-
quest 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=X-
nCHcZ6vQU).

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, de-
scribed 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] sec-
tion 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 Pg-
Bouncer that the config is for. Such an entry will be ignored, but it
is allowed to config management easy. Because it allows using the ex-
act 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 break-
ing 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 con-
nection 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 multi-
ple 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 name-
space 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 con-
figured. Second, they are used as the passwords for outgoing connec-
tions 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 pass-
word-based authentication used in the backend server; plain text, MD5
or SCRAM (see <https://www.postgresql.org/docs/current/auth-pass-
word.html> for details).

MD5-hashed passwords can be used if backend server uses MD5 authentica-
tion (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 Pg-
Bouncer 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_authid 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 authentica-
tion PgBouncer cannot successfully authenticate if it does not know ei-
ther a) user password in plain text or b) corresponding SCRAM secret.

Some cloud providers (i.e. AWS RDS) prohibit access to PostgreSQL sen-
sitive system tables for fetching passwords. Even for the most privi-
leged 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-prac-
tices-for-migrating-postgresql-databases-to-amazon-rds-and-amazon-auro-
ra/)).

Therefore, fetching an existing SCRAM secret once it has been stored in
a managed server is impossible which makes it hard to configure Pg-
Bouncer 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 capa-
ble 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 data-
base-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 $$
BEGIN
SELECT rolname, CASE WHEN rolvaliduntil < now() THEN NULL ELSE rolpassword END
FROM pg_authid
WHERE rolname=i_username AND rolcanlogin
INTO uname, phash;
RETURN;
END;
$$ LANGUAGE plpgsql
SECURITY DEFINER
-- Set a secure search_path: trusted schema(s), then 'pg_temp'.
SET search_path = pg_catalog, pg_temp;
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/>

1.24.1 PGBOUNCER.INI(5)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=pgbouncer&sektion=5&manpath=FreeBSD+Ports+15.0>

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