PGBOUNCER(5)

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 8.x pg_auth/pg_pwd file, so this setting can be pointed directly to one of those backend files. Since version 9.0, PostgreSQL does not use such text file, so it must be generated manually. See section "AUTHENTICATION FILE FORMAT" below about details.

    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.

auth_query

    Query to load user’s password from db.

    Default: SELECT usename, passwd FROM pg_shadow WHERE usename=$1

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

max_db_connections

    Do not allow more than this many connections per-database (regardless of pool - i.e. user). It should be noted that when you hit the limit, closing a client connection to one pool will not immediately allow a server connection to be established for another pool, because the server connection for the first pool is still open. Once the server connection closes (due to idle timeout), a new server connection will immediately be opened for the waiting pool.

    Default: unlimited

max_user_connections

    Do not allow more than this many connections per-user (regardless of pool - i.e. user). It should be noted that when you hit the limit, closing a client connection to one pool will not immediately allow a server connection to be established for another pool, because the server connection for the first pool is still open. Once the server connection closes (due to idle timeout), a new server connection will immediately be opened for the waiting pool.

server_round_robin

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

    Default: 0

ignore_startup_parameters

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

    All 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

application_name_add_host

    Add the client host address and port to the application name setting set on connection start. This helps in identifying the source of bad queries etc. This logic applies only on start of connection, if application_name is later changed with SET, pgbouncer does not change it again.

    Default: 0

conffile

    Show location of current 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.

  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

verbose

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

    Default: 0

  Console access control

admin_users

    Comma-separated list of database users that are allowed to connect and run all commands on console. Ignored when auth_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. If client does use session features, then they will be broken as transaction pooling will not guarantee that next query will be run on same connection.

    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_nxdomain_ttl

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

    Default: 15.0

dns_zone_check_period

    Period to check if zone serial has changed.

    PgBouncer can collect dns zones from 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

suspend_timeout

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

    Default: 10

tcp_defer_accept

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

    Default: 45 on Linux, otherwise 0

tcp_socket_buffer

    Default: not set

tcp_keepalive

    Turns on basic keepalive with OS defaults.

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

auth_user

    If auth_user is set, any user not specified in auth_file will be queried from pg_shadow in the database using auth_user. Auth_user’s password will be taken from auth_file.

  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.

pool_mode

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

max_db_connections

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

  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.

SECTION [USERS]

This contains key=value pairs where key will be taken as a user 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.

  Pool configuration

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.

INCLUDE DIRECTIVE

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

    %include filename

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

AUTHENTICATION FILE FORMAT

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

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

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 auth_user=someuser

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

  Database defaults

    [databases]

    ; foodb over unix socket
    foodb =

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

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

SEE ALSO

pgbouncer(1) - manpage for general usage, console commands.

http://wiki.postgresql.org/wiki/PgBouncer