PgBouncer config

PgBouncer config
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pgbouncer.ini
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_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_connections. 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
(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)
max_user_client_connections
Do not allow more than this many client connections per user (regardless 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 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
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
. 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
. 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 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: 200
scram_iterations
The number of computational iterations to be performed when encrypting a
password using SCRAM-SHA-256. A higher number of iterations provides additional
protection against brute-force attacks on stored passwords, but makes
authentication slower.
Default: 4096
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
authentication method, connections over TCP
must use TLS.
ldap
Users are authenticated against an LDAP server, like in PostgreSQL
(see
for
details). The LDAP connection options are configured using the
setting
auth_ldap_options
, or alternatively in the
auth_hba_file
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_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 function
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 connection string if this parameter is
specified.
auth_ldap_options
LDAP connection options to use if
auth_type
is
ldap
. (Not used if
authentication is configured via
auth_hba_file
.) Example:
auth_ldap_options = ldapurl="ldap://127.0.0.1:12345/dc=example,dc=net?uid?sub"
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
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 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.
If

then send empty query as sanity check.
Default:

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)
query_wait_notify
Time that a client will be queued for before
PgBouncer sends a notification message that they are being
queued. [seconds]
A value of 0 disables this notification message.
Default: 5
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
contents will be used for new connections after a RELOAD. Existing
connections won’t be closed though. If it’s necessary for security
reasons 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 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).
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_tls13_ciphers
Allowed TLS v1.3 ciphers. When empty it will use the value of
client_tls_ciphers
. Allowed values:
TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_GCM_SHA256
TLS_AES_128_CCM_8_SHA256
TLS_AES_128_CCM_SHA256
Only connections using TLS version 1.3 and higher are affected. For version 1.2
and lower see
client_tls_ciphers
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
server_tls13_ciphers
Allowed TLS v1.3 ciphers. When empty it will use the value of
server_tls_ciphers
. Allowed values:
TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_GCM_SHA256
TLS_AES_128_CCM_8_SHA256
TLS_AES_128_CCM_SHA256
Only connections using TLS version 1.3 and higher are affected. For version 1.2
and lower see
client_tls_ciphers
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)
transaction_timeout
If a client has been in “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_size
Set additional connections for this database. If not set, the global
reserve_pool_size
is used. For backwards compatibility reasons
reserve_pool
is an alias for this option.
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.
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 connections).
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_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.
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
reserve_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 transaction open.
If set this timeout overrides the server level idle_transaction_timeout
described above.
transaction_timeout
Set the maximum number of seconds that a user can have a transaction open.
If set this timeout overrides the server level transaction_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 dangerous timeout.
max_user_client_connections
Configure a maximum for the user of client connections. This is the user
equivalent of the max_client_conn setting.
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
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$:$:"
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$:$:
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
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_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 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
).
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
postgres=# \password
Enter new password for user "":
Enter it again:
********* QUERY **********
ALTER USER PASSWORD 'SCRAM-SHA-256$:$:'
**************************
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 password ''
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
).
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
).
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 $$
BEGIN
SELECT rolname, CASE WHEN rolvaliduntil < now() THEN NULL ELSE rolpassword END
FROM pg_authid
WHERE rolname=i_username AND rolcanlogin
INTO uname, phash;
RETURN;
END;
$$ 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