# 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