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
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
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. If 0 then timeout
is disabled. [seconds]
Default: 600
server_connect_timeout
If connection and login won’t 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
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
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 (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 (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)
idle_transaction_timeout
If client has been in "idle in transaction" state longer, it will be
disconnected. [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, 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
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
tcp_keepidle
tcp_keepintvl
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
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.
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.
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¶
; 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