Ubuntu Manpage: pgbouncer - Lightweight connection pooler for PostgreSQL.

NAME

       pgbouncer - Lightweight connection pooler for PostgreSQL.

SYNOPSIS

       [databases]
       db = ...

       [pgbouncer]
       ...

DESCRIPTION

       Config 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 when they appear later in the
       line.

SECTION [PGBOUNCER]

Generic settings
logfile

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

Default: not set.

pidfile

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

Default: not set.

listen_addr

Specifies list of addresses, where to listen for TCP connections. You may also use * meaning "listen
on all addresses". When not set, only Unix socket connections are allowed.

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

Default: not set

listen_port

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

Default: 6432

unix_socket_dir

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

Default: /tmp

unix_socket_mode

Filesystem mode for unix socket.

Default: 0777

unix_socket_group

Group name to use for unix socket.

Default: not set

user

If set, specifies the Unix user to change to after startup. Works only if PgBouncer is started as
root or if user is the same as the current user. Note: Not supported on Windows machines.

Default: not set

auth_file

The name of the file to load user names and passwords from. The file format is the same as the
PostgreSQL pg_auth/pg_pwd file, so this setting can be pointed directly to one of those backend
files.

Default: not set.

auth_type

How to authenticate users.

md5
Use MD5-based password check. auth_file may contain both MD5-encrypted or plain-text passwords.
This is the default authentication method.

crypt
Use crypt(3) based password check. auth_file must contain plain-text passwords.

plain
Clear-text password is sent over wire.

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

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

pool_mode

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

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

transaction
Server is released back to pool after transaction finishes.

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

max_client_conn

Maximum number of client connections allowed. When increased then the file descriptor limits should
also be increased. Note that actual number of file descriptors used is more than max_client_conn.
Theoretical maximum used is:

max_client_conn + (max_pool_size * total_databases * total_users)

if each user connects under its own username to server. If a database user is specified in connect
string (all users connect under same username), the theoretical maximum is:

max_client_conn + (max_pool_size * total_databases)

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

Search for ulimit in your favourite 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 behaviour when usual load comes
suddenly back after period of total inactivity.

Default: 0 (disabled)

reserve_pool_size

How many additional connections to allow to a pool. 0 disables.

Default: 0 (disabled)

reserve_pool_timeout

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

Default: 5.0

server_round_robin

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

Default: 0

ignore_startup_parameters

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

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

Default: empty

disable_pqexec

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

Default: 0

Log settings
syslog

Toggles syslog on/off As for windows environment, eventlog is used instead.

Default: 0

syslog_ident

Under what name to send logs to syslog.

Default: pgbouncer (program name)

syslog_facility

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

Default: daemon

log_connections

Log successful logins.

Default: 1

log_disconnections

Log disconnections with reasons.

Default: 1

log_pooler_errors

Log error messages pooler sends to clients.

Default: 1

stats_period

Period for writing aggregated stats into log.

Default: 60

Console access control
admin_users

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

Default: empty

stats_users

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

Default: empty.

Connection sanity checks, timeouts
server_reset_query

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

A good choice for Postgres 8.2 and below is:

server_reset_query = RESET ALL; SET SESSION AUTHORIZATION DEFAULT;

for 8.3 and above its enough to do:

server_reset_query = DISCARD ALL;

When transaction pooling is used, the server_reset_query should be empty, as clients should not use
any session features.

Default: DISCARD ALL

server_check_delay

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

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_lifetime

The pooler will try to close server connections that have been connected longer than this. Setting it
to 0 means the connection is to be used only once, then closed. [seconds]

Default: 3600.0

server_idle_timeout

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

Default: 600.0

server_connect_timeout

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

Default: 15.0

server_login_retry

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

Default: 15.0

client_login_timeout

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

Default: 60.0

autodb_idle_timeout

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

Default: 3600.0

dns_max_ttl

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

Default: 15.0

dns_zone_check_period

Period to check if zone serial has changed.

PgBouncer can collect dns zones from hostnames (everything after first dot) and then periodically
check if zone serial changes. If it notices changes, all hostnames under that zone are looked up
again. If any host ip changes, it’s connections are invalidated.

Works only with UDNS backend (--with-udns to configure).

Default: 0.0 (disabled)

Dangerous timeouts
Setting following timeouts cause unexpected errors.

query_timeout

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

Default: 0.0 (disabled)

query_wait_timeout

Maximum time queries are allowed to spend waiting for execution. If the query is not assigned to a
server during that time, the client is disconnected. This is used to prevent unresponsive servers
from grabbing up connections. [seconds]

Default: 0.0 (disabled)

client_idle_timeout

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

Default: 0.0 (disabled)

idle_transaction_timeout

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

Default: 0.0 (disabled)

Low-level network settings
pkt_buf

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

Default: 2048

max_packet_size

Maximum size for Postgres packets that PgBouncer allows through. One packet is either one query or
one resultset row. Full resultset can be larger.

Default: 2147483647

listen_backlog

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

Default: 128

sbuf_loopcnt

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

Default: 5

tcp_defer_accept

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

Default: 45 on Linux, otherwise 0

tcp_socket_buffer

Default: not set

tcp_keepalive

Turns on basic keepalive with OS defaults.

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

Default: 1

tcp_keepcnt

Default: not set

tcp_keepidle

Default: not set

tcp_keepintvl

Default: not set

SECTION [DATABASES]

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

Database name can contain characters [0-9A-Za-z_.-] without quoting. Names that contain other chars need
to be quoted with standard SQL ident quoting: double quotes where "" is taken as single quote.

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

Location parameters
dbname

Destination database name.

Default: same as client-side database name.

host

Hostname or IP address to connect to. Hostnames are resolved on connect time, the result is cached
per dns_max_ttl parameter. If DNS returns several results, they are used in round-robin manner.

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

port

Default: 5432

user, password

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

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

Pool configuration
pool_size

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

connect_query

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

Extra parameters
They allow setting default parameters on server connection.

Note that since version 1.1 PgBouncer tracks client changes for their values, so their use in
pgbouncer.ini is deprecated now.

client_encoding

Ask specific client_encoding from server.

datestyle

Ask specific datestyle from server.

timezone

Ask specific timezone from server.

AUTHENTICATION FILE FORMAT

       PgBouncer needs its own user database. The users are loaded from a text file in following format:

           "username1" "password" ...
           "username2" "md5abcdef012342345" ...

       There should be at least 2 fields, surrounded by double quotes. The first field is the username and the
       second is either a plain-text or a MD5-hidden password. PgBouncer ignores the rest of the line.

       This file format is equivalent to text files used by PostgreSQL 8.x for authentication info, thus
       allowing PgBouncer to work directly on PostgreSQL authentication files in data directory.

       Since PostgreSQL 9.0, the text files are not used anymore. Thus the auth file needs to be generated. See
       ./etc/mkauth.py for sample script to generate auth file from pg_shadow table.

       PostgreSQL MD5-hidden password format:

           "md5" + md5(password + username)

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

EXAMPLE

   Minimal config
           [databases]
           template1 = host=127.0.0.1 dbname=template1

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

   Database defaults
           [databases]

           ; foodb over unix socket
           foodb =

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

           ; access to destination database will go with single user
           forcedb = host=127.0.0.1 port=300 user=baz password=foo client_encoding=UNICODE datestyle=ISO

NAME

SYNOPSIS

DESCRIPTION

SECTION [PGBOUNCER]

SECTION [DATABASES]

AUTHENTICATION FILE FORMAT

EXAMPLE

SEE ALSO