pgbouncer

Manages database connection pools.

Synopsis

pgbouncer [OPTION ...] config.ini

  OPTION
   [ -d | --daemon ]
   [ -R | --restart ]
   [ -q | --quiet ]
   [ -v | --verbose ]
   [ {-u | --user}=username ]

pgbouncer [ -V | --version ] | [ -h | --help ]

Description

PgBouncer is a light-weight connection pool manager for Greenplum and PostgreSQL databases. Databases may be on different Greenplum Database clusters or PostgreSQL backends. PgBouncer creates a pool for each database user and database combination. A pooled connection can only be reused for another connection request for the same user and database. The client application connects to the connection pool's host and port instead of the Greenplum Database master host and port. PgBouncer either creates a new database connection for the client or reuses an existing connection. When the client disconnects, the connection is returned to the pool for re-use.

PgBouncer supports the standard connection interface that PostgreSQL and Greenplum Database share. A client requesting a database connection provides the host name and port where PgBouncer is running, as well as the database name, username, and password. PgBouncer looks up the requested database (which may be an alias for the actual database) in its configuration file to find the host name, port, and database name for the database connection. The configuration file entry also determines how to authenticate the user and what database role will be used for the connection—a "forced user" can override the username provided with the client's connection request.

PgBouncer requires an authentication file, a text file that contains a list of users and passwords. Passwords may be either clear text, MD5-encoded, or an LDAP/AD lookup string. You can also set up PgBouncer to query the pg_shadow table in the destination database for users that are not in the authentication file.

PgBouncer shares connections in one of three pool modes:

Session pooling – When a client connects, a connection is assigned to it as long as it remains connected. When the client disconnects, the connection is placed back into the pool.
Transaction pooling – A connection is assigned to a client for the duration of a transaction. When PgBouncer notices the transaction is done, the connection is placed back into the pool. This mode can be used only with applications that do not use features that depend upon a session.
Statement pooling – Statement pooling is like transaction pooling, but multi-statement transactions are not allowed. This mode is intended to enforce autocommit mode on the client and is targeted for PL/Proxy on PostgreSQL.

A default pool mode can be set for the PgBouncer instance and the mode can be overridden for individual databases and users.

By connecting to a virtual pgbouncer database, you can monitor and manage PgBouncer using SQL-like commands. Configuration parameters can be changed without having to restart PgBouncer, and the configuration file can be reloaded to pick up changes.

PgBouncer does not yet support SSL connections. If you want to encrypt traffic between clients and PgBouncer, you can use stunnel, a free software utility that creates TLS-encrypted tunnels using the OpenSSL cryptography library. See "Securing PgBouncer Connections with stunnel" in the Greenplum Database Administrator Guide for directions.

See the PgBouncer FAQ for additional usage information.

This reference topic includes the following additional reference information:

Options

-d | --daemon: Run PgBouncer as a daemon (a background process). The default is to run as a foreground process.; PgBouncer displays start up messages when starting as a daemon. To disable the display of messages add the -q option.; To shut down a PgBouncer daemon, log in to the administration console and issue the SHUTDOWN command.
Note: This option does not work on Windows servers.
-R | --restart: Restart PgBouncer using the specified command line arguments. Non-TLS connections to databases are maintained during restart; TLS connections are dropped.; If you specify only the -R option, PgBouncer displays log information on the command line after restart. To restart PgBouncer as a daemon specify the options -Rd.
Note: Works only if the operating system supports Unix sockets and the PgBouncer configuration has no unix_socket_dir. This option does not work on Windows servers.
-q | --quiet: Run quietly. Do not display messages on the command line (stdout).
-v | --verbose: Increase message verbosity. Display additional messages. Can be used multiple times.
{-u | --user}=username: The PgBouncer process assumes the identity of username.
-V | --version: Show version and exit.
-h | --help: Show help message and exit.

PgBouncer Configuration File

The PgBouncer configuration file (usually pgbouncer.ini) is in the "ini" format. Section names are enclosed in square braces ([ and ]). Lines beginning with ";" or "#" are comments and are ignored. The characters ";" and "#" are not recognized when they appear later in the line.

Synopsys

[databases]
db = ...

[pgbouncer]
...

[users]
...

Description

A PgBouncer configuration file has up to three sections:

[databases] Section

The databases section contains key=value pairs, where the key is a database name and the value is a libpq connect-string list of key=value pairs.

A database name can contain characters [0-9A-Za-z_.-] without quoting. Names that contain other chars must be quoted with standard SQL identifier quoting

Enclose names in double quotes (")
Represent a double-quote within an identifier with two consecutive double quote characters

The database name "*" is the fallback database. The value for this key is a connect string for the requested database. Automatically created database entries like these are cleaned up if they remain idle longer then the time specified in autodb_idle_timeout parameter.

The PgBouncer configuration file can contain %include directives, which specify another filee to read and process. This allows splitting the configuration file into separate parts. For example:

%include filename

Location Parameters

The following parameters may be included in the value to specify the location of the database.

dbname: The destination database name.
Default: same as the client-side database name.
host: The name or IP address of the Greenplum master host. Host names are resolved at connect time. If DNS returns several results, they are used in a round-robin manner. The DNS result is cached and the dns_max_ttl parameter determines when the cache entry expires.; Default: not set, means the connection is made through a Unix socket.
port: The Greenplum Database master port. Default: 5432
user, password: If user= is set, all connections to the destination database are made with the specified user. This means there will be just one pool for the database.
If the user= parameter is not set, PgBouncer attempts to log in to the destination database with the user name passed by the client. This means there will be one pool for each user who connects to the database.
auth_user: If auth_user is set, any user who is not specified in auth_file is authenticated by querying the pg_shadow table in the database as the auth_user. The auth_user password must be set in the 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 for this database. If not set, the default pool_mode is used.
max_db_connections: Set a database-wide maximum number of connections for this database. The total number of connections for all pools for this database will not exceed this value.

Extra Parameters

The following parameters allow setting default parameters on server connections.

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] Section

logfile

Specifies the location of the log file. The log file is kept open. After log rotation execute kill -HUP or run the RELOAD; command in the PgBouncer Administrative Console.

Default: not set.

Note: On Windows machines, the service must be stopped and started

pidfile

The name of the pid file. Without a pidfile, PgBouncer cannot be run as a background process (daemon).

Default: not set.

listen_addr

A list of interface addresses where PgBouncer listens for TCP connections. You may also use *, which means to listen on all interfaces. If 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 option) 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. This only works 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 containing the user names and passwords to load. The file format is the same as the Greenplum Database pg_auth/pg_pwd file, so this parameter can be set to one of those backend files. See Authentication File Format for details.

Default: not set.

auth_hba_file

HBA configuration file to use when auth_type is hba.

auth_type

How to authenticate users.

hba: Actual auth type is loaded from auth_hba_file. This allows different authentication methods different access paths. For example Unix socket connections use peer auth method; TCP connections must use TLS.
cert: Clients must connect with TLS using a valid client certificate. The client's username is taken from CommonName field in the certificate.
md5: Use MD5-based password check. auth_file may contain both MD5-encrypted or plain-text passwords. This is the default authentication method.
plain: Clear-text password is sent over wire. Deprecated.
trust: No authentication is done. The username must still exist in the auth_file.
any: Like the trust method, but the username supplied is ignored. Requires that all databases are configured to log in with a specific user. Additionally, the console database allows any user to log in as admin.

auth_query

Query to load a user's password from database. If a user does not exist in the auth_file and the database entry includes an auth_user, this query is run in the database as auth_user to lookup up the user.

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

pool_mode

Specifies when a server connection can be reused by other clients.

session: Connection is returned to the pool when the client disconnects. Default.
transaction: Connection is returned to the pool when the transaction finishes.
statement: Connection is returned to the pool when the current query finishes. Long transactions with 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. The actual number of file descriptors used is more than max_client_conn. The theoretical maximum used, when each user connects with its own username to the server is:

max_client_conn + (max_pool_size * total_databases * total_users)

If a database user is specified in the connect string, all users connect using the same username. Then the theoretical maximum connections is:

max_client_conn + (max_pool_size * total_databases)

The theoretical maximum should be never reached, unless somone deliberately crafts a load for it. Still, it means you should set the number of file descriptors to a safely high number. Search for ulimit in your operating system documentation.

Note: ulimit does not apply in a Windows environment.

Default: 100

default_pool_size

The number of server connections to allow per user/database pair. This can be overridden in the per-database configuration.

Default: 20

min_pool_size

Add more server connections to the pool when it is lower than this number. This improves behavior when the usual load drops and then returns suddenly after a period of total inactivity.

Default: 0 (disabled)

reserve_pool_size

The number of additional connections to allow for 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

The maximum number of connections per database. If you hit the limit, closing a client connection to one pool does 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 be opened for the waiting pool.

Default: unlimited

max_user_connections

The maximum number of connections per-user. When you hit the limit, closing a client connection to one pool does not immediately allow a connection to be established for another pool, because the connection for the first pool is still open. After the connection for the first pool has closed (due to idle timeout), a new server connection is opened for the waiting pool.

server_round_robin

By default, PgBouncer reuses server connections in LIFO (last-in, first-out) order, so that a few connections get the most load. This provides the best performance when a single server serves 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 to achieve 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 raise an error. To allow other parameters, specify them here so that PgBouncer can ignore them.

Default: empty

disable_pqexec

Disable Simple Query protocol (PQexec). Unlike Extended Query protocol, Simple Query protocol allows multiple queries in one packet, which allows some classes of SQL-injection attacks. Disabling it can improve security. This means that only clients that exclusively use Extended Query protocol will work.

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. The setting is overwritten without detection if the application executes SET APPLICATION_NAME after connecting.

Default: 1

Log Settings

syslog: Toggles syslog on and off. On Windows, eventlog is used instead.
Default: 0
syslog_ident: Under what name to send logs to syslog.
Default: pgbouncer
syslog_facility: Under what facility to send logs to syslog. Some possibilities are: 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 that the pooler sends to clients.
Default: 1
stats_period: How often to write aggregated statistics to the 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, and Greenplum Database, is:

server_reset_query = RESET ALL; SET SESSION AUTHORIZATION DEFAULT;

For Postgre 8.3 and above, the following is sufficient:

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 clients do use session features, they will be broken because transaction pooling does not guarantee that the next query will run on the same connection.

Default: DISCARD ALL

server_reset_query_always

Whether server_reset_query should be run in all pooling modes. When this setting is off (default), the server_reset_query will be run only in pools that are in sessions pooling mode. Connections in transaction pooling mode should not have any need for reset query.

Default: 0

server_check_delay

How long to keep released connections available for re-use without running sanity-check queries on it. If 0 then the query is run always.

Default: 30.0

server_check_query

A simple do-nothing query to test the server connection.

If an empty string, then sanity checking is disabled.

Default: SELECT 1;

server_lifetime

The pooler tries to close server connections that have been connected longer than this number of seconds. Setting it to 0 means the connection is to be used only once, then closed.

Default: 3600.0

server_idle_timeout

If a server connection has been idle more than this many seconds it is dropped. If this parameter is set to 0, timeout is disabled. [seconds]

Default: 600.0

server_connect_timeout

If connection and login will not finish in this number of seconds, the connection will be closed.

Default: 15.0

server_login_retry

If a login fails due to failure from connect() or authentication, the pooler waits this many seconds before retrying to connect.

Default: 15.0

client_login_timeout

If a client connects but does not manage to login in this number of seconds, it is disconnected. This is needed to avoid dead connections stalling SUSPEND and thus online restart.

Default: 60.0

autodb_idle_timeout

If database pools created automatically (via "*") have been unused this many seconds, they are freed. Their statistics are also forgotten.

Default: 3600.0

dns_max_ttl

How long to cache DNS lookups, in seconds. If a DNS lookup returns several answers, PgBouncer round-robins between them in the meantime. The actual DNS TTL is ignored.

Default: 15.0

dns_nxdomain_ttl

How long error and NXDOMAIN DNS lookups can be cached, in seconds.

Default: 15.0

dns_zone_check_period

Period to check if zone serial numbers have changed.

PgBouncer can collect DNS zones from hostnames (everything after first dot) and then periodically check if the zone serial numbers change. If changes are detected, all hostnames in that zone are looked up again. If any host IP changes, its connections are invalidated.

Works only with UDNS backend (--with-udns to configure).

Default: 0.0 (disabled)

Dangerous Timeouts

Setting tje following timeouts can cause unexpected errors.

query_timeout: Queries running longer than this (seconds) are canceled. This parameter should be used only with a slightly smaller server-side statement_timeout, to trap queries with network problems. [seconds]
Default: 0.0 (disabled)
query_wait_timeout: The maximum time, in seconds, queries are allowed to wait for execution. If the query is not assigned a connection during that time, the client is disconnected. This is used to prevent unresponsive servers from grabbing up connections.
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.
Default: 0.0 (disabled)
idle_transaction_timeout: If client has been in "idle in transaction" state longer than this (seconds), it is disconnected.
Default: 0.0 (disabled)

Low-level Network Settings

pkt_buf

Internal buffer size for packets. Affects the size of TCP packets sent and general memory usage. Actual libpq packets can be larger than this so there is no need to set it large.

Default: 2048

max_packet_size

Maximum size for packets that PgBouncer accepts. One packet is either one query or one result set row. A full result set can be larger.

Default: 2147483647

listen_backlog

Backlog argument for the listen(2) system call. It how many new unanswered connection attempts are kept in queue. When the queue is full, further new connection attemps 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 result set 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 the tcp(7) man page.

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.

Default: 1

tcp_keepcnt

Default: not set

tcp_keepidle

Default: not set

tcp_keepintvl

Default: not set

[users] Section

This section contains key=value pairs, where the key is a user name and the value is a libpq connect-string list of key=value pairs.

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.

Example Configuration Files

Minimal Configuration

[databases]
template1 = host=127.0.0.1 dbname=template1 auth_user=gpadmin

[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

Use connection parameters passed by the client:

[databases]
* =

[pgbouncer]
listen_port = 65432
listen_addr = 0.0.0.0
auth_type = trust
auth_file = bouncer/users.txt
logfile = pgbouncer.log
pidfile = pgbouncer.pid
ignore_startup_parameters=options

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

PgBouncer Authentication File Format

PgBouncer requires its own user database, a text file in following format:

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

There is one line per user. Each line must have at least two fields. Fields are enclosed in double quotes ("). The first field is the user name and the second is either a plain-text or an MD5-encoded password. The remainder of the line is ignored.

This file format is similar to text files used by Greenplum Database for authentication information, and PgBouncer can work directly with the Greenplum Database authentication files.

To avoid plain-text passwords, encode user passwords with MD5. The format for an MD5 encoded password is:

"md5" + md5(password + username)

For example, the following command generates the MD5 string for the user admin with password 1234:

$ echo -n "1234admin" | md5sum
$ 45f2603610af569b6155c45067268c6b

The MD5-hidden password is:

md545f2603610af569b6155c45067268c6b

PgBouncer HBA File Format

The PgBouncer HBA file follows the format of the PostgreSQL pg_hba.conf file. See http://www.postgresql.org/docs/9.4/static/auth-pg-hba-conf.html for details.

The PgBouncer HBA file differs from the PostgreSQL file format in the following ways:

Supported record types: local, host, hostssl, hostnossl.
Database field: Supports all, sameuser, @file, multiple names. Not supported: replication, samerole, samegroup.
Username field: Supports all, @file, multiple names. Not supported +groupname.
Address field: Supported IPv4, IPv6. Not supported: DNS names, domain prefixes.
Auth-method field: Supported methods: trust, reject, jd5, password, peer, cert. Not supported: gss, sspi, ident, ldap, radius, pam. Also username map (map=) parameter is not supported.

PgBouncer Administration Console Commands

The PgBouncer Administration Console is accessed by connecting to the database pgbouncer.

$ psql -p 6543 pgbouncer

Only users listed in configuration parameters admin_users or stats_users can log in to the console. However, when auth_mode=any, then any user may log in as a stats_user.

The user name pgbouncer may also log in without a password through a Unix socket if the client has the same Unix user UID as the running process.

Administration Console Command Syntax

pgbouncer=# show help;
NOTICE:  Console usage
DETAIL:
       SHOW HELP|CONFIG|DATABASES|POOLS|CLIENTS|SERVERS|VERSION
	SHOW STATS|FDS|SOCKETS|ACTIVE_SOCKETS|LISTS|MEM
	SHOW DNS_HOSTS|DNS_ZONES
	SET key = arg
	RELOAD
	PAUSE [<db>]
	RESUME [<db>]
	DISABLE <db>
	ENABLE <db>
	KILL <db>
	SUSPEND
	SHUTDOWN

Administration Commands

From the PgBouncer Administrator console you can control connections between PgBouncer and Greenplum Database.You can also set PgBouncer configuration parameters.

The following PgBouncer administration commands control the PgBouncer process.

PAUSE [database]: If no database is specified, PgBouncer tries to disconnect from all servers, first waiting for all queries to complete. The command will not return before all queries are finished. This command is to be used to prepare to restart the database.; If a database name is specified, only that database is paused.; If you run a PAUSE database command, and then a PAUSE command to pause all databases, you must execute two RESUME commands, one for all databases, and one for the named database.
SUSPEND: All socket buffers are flushed and PgBouncer stops listening for data on them. The command will not return before all buffers are empty. To be used when rebooting PgBouncer online.
RESUME [ database ]: Resume work from a previous PAUSE or SUSPEND command.; If a database was specified for the PAUSE command, the database must also be specified with the RESUME command.; After pausing all databases with the PAUSE command, resuming a single database with RESUME database is not supported.
DISABLE database: Reject all new client connections on the database.
ENABLE database: Allow new client connections on the database.
KILL database: Immediately drop all client and server connections to the named database.
SHUTDOWN: Stop PgBouncer process. To exit from the psql command line session, enter \q.
RELOAD: The PgBouncer process reloads the current configuration file and updates the changeable settings.
SET key = value: Override specified configuration setting. See the SHOW CONFIG; command.

SHOW Command

The SHOW category command displays different types of PgBouncer information. You can specify one of the following categories:

ACTIVE_SOCKETS

Table 1. Active Socket Information
Column	Description
type	S, for server, C for client.
user	Username `pgbouncer` uses to connect to server.
database	Database name.
state	State of the server connection, one of `active`, `used` or `idle`.
addr	IP address of PostgreSQL server.
port	Port of PostgreSQL server.
local_addr	Connection start address on local machine.
local_port	Connection start port on local machine.
connect_time	When the connection was made.
request_time	When last request was issued.
ptr	Address of internal object for this connection. Used as unique ID.
link	Address of client connection the server is paired with.
recv_pos	Receive position in the I/O buffer.
pkt_pos	Parse position in the I/O buffer.
pkt_remain	Number of packets remaining on the socket.
send_pos	Send position in the packet.
send_remain	Total packet length remaining to send.
pkt_avail	Amount of I/O buffer left to parse.
send_avail	Amount of I/O buffer left to send.

CLIENTS

Table 2. Clients
Column	Description
type	C, for client.
user	Client connected user.
database	Database name.
state	State of the client connection, one of `active`, `used`, `waiting` or `idle`.
addr	IP address of client, or `unix` for a socket connection.
port	Port client is connected to.
local_addr	Connection end address on local machine.
local_port	Connection end port on local machine.
connect_time	Timestamp of connect time.
request_time	Timestamp of latest client request.
ptr	Address of internal object for this connection. Used as unique ID.
link	Address of server connection the client is paired with.
remote_pid	Process ID, if client connects with Unix socket and the OS supports getting it.

CONFIG

List of current PgBouncer parameter settings

Table 3. Config
Column	Description
key	Configuration variable name
value	Configuration value
changeable	Either `yes` or `no`. Shows whether the variable can be changed while running. If `no`, the variable can be changed only at boot time.

DATABASES

Table 4. Databases
Column	Description
name	Name of configured database entry.
host	Host pgbouncer connects to.
port	Port pgbouncer connects to.
database	Actual database name pgbouncer connects to.
force_user	When user is part of the connection string, the connection between pgbouncer and the database server is forced to the given user, whatever the client user.
pool_size	Maximum number of server connections.
reserve_pool	The number of additional connections that can be created if the pool reaches `pool_size`.
pool_mode	The database's override `pool_mode` or NULL if the default will be used instead.
max_connections	Maximum number of connections for all pools for this database.
current_connections	The total count of connections for all pools for this database.

DNS_ZONES

Table 5. DNS Zones in Cache
Column	Description
zonename	Zone name
serial	Current DNS serial number
count	Hostnames belonging to this zone

FDS

SHOW FDS is an internal command used for an online restart, for example when upgrading to a new PgBouncer version. It shows a list of file descriptors in use with the internal state attached to them. This command blocks the internal event loop, so it should not be used while PgBouncer is in use.

When the connected user has username "pgbouncer", connects through a Unix socket, and has the same UID as the running process, the actual file descriptors are passed over the connection. Note: This does not work on Windows machines.

Table 6. FDS
Column	Description
fd	File descriptor numeric value.
task	One of `pooler`, `client`, or `server`.
user	User of the connection using the file descriptor.
database	Database of the connection using the file descriptor.
addr	IP address of the connection using the file descriptor, "unix" if a Unix socket is used.
port	Port used by the connection using the file descriptor.
cancel	Cancel key for this connection.
link	File descriptor for corresponding server/client. NULL if idle.
client_encoding	Character set used for the database.
std_strings	This controls whether ordinary string literals ('...') treat backslashes literally, as specified in the SQL standard.
datestyle	Display format for date and time values.
timezone	The timezone for interpreting and displaying time stamps.

LISTS

Shows the following PgBouncer statistcs in two columns: the item label and value.

Table 7. Count of PgBouncer Items
Item	Description
databases	Count of databases.
users	Count of users.
pools	Count of pools.
free_clients	Count of free clients.
used_clients	Count of used clients.
login_clients	Count of clients in `login` state.
free_servers	Count of free servers.
used_servers	Count of used servers.
dns_names	Count of DNS names.
dns_zones	Count of DNS zones.
dns_queries	Count of DNS queries.
dns_pending	Count of in-flight DNS queries.

MEM

Shows cache memory information for these PgBouncer caches:

user_cache
db_cache
pool_cache
server_cache
client_cache
iobuf_cache

Table 8. In Memory Cache
Column	Description
name	Name of cache.
size	The size of a single slot in the cache.
used	Number of used slots in the cache.
free	The number of available slots in the cache.
memtotal	Total bytes used by the cache.

POOLS

A new pool entry is made for each pair of (database, user).

Table 9. Pools
Column	Description
database	Database name.
user	User name.
cl_active	Client connections that are linked to server connection and can process queries.
cl_waiting	Client connections have sent queries but have not yet got a server connection.
sv_active	Server connections that linked to client.
sv_idle	Server connections that are unused and immediately usable for client queries.
sv_used	Server connections that have been idle more than `server_check_delay`. The `server_check_query` query must be run on them before they can be used.
sv_tested	Server connections that are currently running either `server_reset_query` or `server_check_query`.
sv_login	Server connections currently in process of logging in.
maxwait	How long the first (oldest) client in the queue has waited, in seconds. If this begins to increase, the current pool of servers does not handle requests fast enough. The cause may be either an overloaded server or the `pool_size` setting is too small.
pool_mode	The pooling mode in use.

SERVERS

Table 10. Servers
Column	Description
type	S, for server.
user	User ID that `pgbouncer` uses to connect to server.
database	Database name.
state	State of the pgbouncer server connection, one of `active`, `used`, or `idle`.
addr	IP address of the Greenplum or PostgreSQL server.
port	Port of the Greenplum or PostgreSQL server.
local_addr	Connection start address on local machine.
local_port	Connection start port on local machine.
connect_time	When the connection was made.
request_time	When the last request was issued.
ptr	Address of the internal object for this connection. Used as unique ID.
link	Address of gthe client connection the server is paired with.
remote_pid	Pid of backend server process. If the connection is made over Unix socket and the OS supports getting process ID info, it is the OS pid. Otherwise it is extracted from the cancel packet the server sent, which should be PID in case server is PostgresSQL, but it is a random number in case server is another PgBouncer.

STATS

Shows statistics.

Table 11. Stats
Column	Description
database	Statistics are presented per database.
total_requests	Total number of `SQL` requests pooled by `pgbouncer`.
total_received	Total volume in bytes of network traffic received by `pgbouncer`.
total_sent	Total volume in bytes of network traffic sent by `pgbouncer`.
total_query_time	Total number of microseconds spent by `pgbouncer` when actively connected to the database server.
avg_req	Average requests per second in last stat period.
avg_recv	Average received (from clients) bytes per second.
avg_sent	Average sent (to clients) bytes per second.
avg_query	Average query duration in microseconds.

USERS

Table 12. Users
Column	Description
name	The user name
pool_mode	The user's override pool_mode, or NULL if the default will be used instead.

VERSION

Display PgBouncer version information.

Note: This reference documentation is based on the PgBouncer 1.6.1 documentation.