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pgbouncer

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 IPv4 address, where to listen for TCP connections. You may also use * meaning "listen on all addresses". When not set, only Unix socket connections are allowed.
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. Note: Not supported on Windows machines.
Default: /tmp

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 overriden in the per-database configuration.
Default: 20

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

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

 

Log settings

syslog

Toggles syslog on/off As for windows environment, eventlog is used instead.
Default: 0

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

 

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.
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;
 

server_check_delay

How long to keep released connections available for immidiate re-use, without running sanity-check queries on it. If 0 then the query is ran always.
Default: 30

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

server_idle_timeout

If a server connection has been idle more than this many seconds, and there are too many connections in the pool, this one can be dropped. [seconds]
Default: 600

server_connect_timeout

If connection and login woncqt finish in this amount of time, the connection will be closed. [seconds]
Default: 15

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

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

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

 

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 (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 (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 (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

listen_backlog

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

Default: not set

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

IP address to connect to.
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 allowingf 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 that should be in same format as PostgreSQLcqs pg_auth/pg_pwd file.

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

There shoud 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-hashed password. PgBouncer ignores the rest of the line.

This file format allows you to directly use the existing PostgreSQL authentication files in the Postgres data directory.

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
 

SEE ALSO

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

m[blue]http://pgbouncer.projects.postgresql.org/doc/m[]

m[blue]https://developer.skype.com/SkypeGarage/DbProjects/PgBouncerm[]