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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 comment 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.
Default: not set.

pidfile

Specifies pid file. Without pidfile, the daemonization is not allowed.
Default: not set.

listen_addr

Specifies IPv4 address, where to listen for TCP connections. Or * meaning "listen on all addresses". When not set, only unix socket connections are allowed.
Default: not set

listen_port

On which port to listen on. Applies to both TCP and Unix sockets.
Default: 6000

unix_socket_dir

Specifies location for Unix sockets. Applies to both listening socket and server connections. If set to empty string, Unix sockets are disabled.
Default: /tmp

user

If set, specifies UNIX user to change to. Work only if started as root or user is same as current user.
Default: not set

auth_file

Load user names and passwords from this file. File format used is same as for PostgreSQL pg_auth/pg_pwd file, so can be pointed directly to backend file.
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. Default.

crypt

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

plain

Clear-text password is sent over wire.

trust

No authentication is done. Username must still exists in auth_file.

any

Like trust but username given is ignored. Requires that all databases have configured to log in as specific user.

pool_mode

Specifies when server connection is tagged as reusable for 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 descriptiors used is more that max_client_conn. Theoretical maximum used is:

 max_client_conn + (max_pool_size * total_databases * total_users)
 

if each user connects under it's own username to server. If 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 give fds liberately.

Search for ulimit in your favourite shell man page.

Default: 100

default_pool_size

How many server connection to allow per user/database pair. Can be overrided in per-database config.
Default: 20

server_round_robin

By default, pgbouncer reuses server connections in LIFO manner, so that few connections get the most load. This gives best performance if you have single server serving a database. But if there is TCP round-robin behind a database IP then it's 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 raise error. To allow others too, 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
Default: 0

syslog_facility

Under what facility to send log 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 messaged pooler sends to clients.
Default: 1

Console access control

admin_users

Comma-separted list of database users that are allowed to connect and run all commands on console.
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 send 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 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 immidiately available, without running sanity-check query on it. If 0 then the query is ran always.
Default: 30

server_check_query

Simple do-nothing query to check if server connection is alive.
If empty string, then sanity checking is disabled.
Default: SELECT 1;

server_lifetime

Pooler tries to close server connections that are been connected longer than this. Setting it to 0 means the connection is to be used only once, then closed.
Default: 3600

server_idle_timeout

If server connection has been idle more than this then there's too many connections in the pool and this one can be dropped.
Default: 600

server_connect_timeout

If connection and login wont finish in this time, the connection will be closed.
Default: 15

server_login_retry

If login failed, because of failure from connect() or authentication that pooler waits this much before retrying to connect.
Default: 15

client_login_timeout

If client connect but does not manage to login in this time, it will be disconnected. Mainly needed to avoid dead connections stalling SUSPEND and thus online restart.
Default: 60

Dangerous timeouts

Setting following timeouts cause unexcpected 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.
Default: 0 (disabled)

client_idle_timeout

Client connections idling longer than that are closed. This should be larger then client-side connection lifetime settings, to apply only for network problems.
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

tcp_defer_accept

Details about following options shouldbe looked from 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 database name and value as libpq-connstring style list of key=value pairs. As actual libpq is not used, so not all features from libpq can be used (service=, quoting).

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 unix-socket.

port

Default: 5432

user, password

If user= is set, all connections to destination database will be done with that user, meaning that there will be only one pool for this database.
Otherwise pgbouncer tries to log into 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 connecttion is established, but before taking the connection into use by 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 text file that should be in same format as PostgreSQL's pg_auth/pg_pwd file.

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

There shoud be at least 2 fields, surrounded by double quotes. First is username and second either plain-text or md5-hashed password. PgBouncer ignores rest of the line.

Such file format allows to direct PgBouncer directly to PostgreSQL user file under 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
 

 ; acceess to dest 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.

https://developer.skype.com/SkypeGarage/DbProjects/PgBouncer