Provided by: pgbouncer_1.23.1-1_amd64 
NAME
pgbouncer - lightweight connection pooler for PostgreSQL
SYNOPSIS
pgbouncer [-d][-R][-v][-u user] <pgbouncer.ini>
pgbouncer -V|-h
On Windows, the options are:
pgbouncer.exe [-v][-u user] <pgbouncer.ini>
pgbouncer.exe -V|-h
Additional options for setting up a Windows service:
pgbouncer.exe --regservice <pgbouncer.ini>
pgbouncer.exe --unregservice <pgbouncer.ini>
DESCRIPTION
pgbouncer is a PostgreSQL connection pooler. Any target application can be connected to
pgbouncer as if it were a PostgreSQL server, and pgbouncer will create a connection to the
actual server, or it will reuse one of its existing connections.
The aim of pgbouncer is to lower the performance impact of opening new connections to
PostgreSQL.
In order not to compromise transaction semantics for connection pooling, pgbouncer
supports several types of pooling when rotating connections:
Session pooling
Most polite method. When a client connects, a server connection will be assigned
to it for the whole duration the client stays connected. When the client
disconnects, the server connection will be put back into the pool. This is the
default method.
Transaction pooling
A server connection is assigned to a client only during a transaction. When
PgBouncer notices that transaction is over, the server connection will be put back
into the pool.
Statement pooling
Most aggressive method. The server connection will be put back into the pool
immediately after a query completes. Multi-statement transactions are disallowed
in this mode as they would break.
The administration interface of pgbouncer consists of some new SHOW commands available
when connected to a special “virtual” database pgbouncer.
QUICK-START
Basic setup and usage is as follows.
1. Create a pgbouncer.ini file. Details in pgbouncer(5). Simple example:
[databases]
template1 = host=localhost port=5432 dbname=template1
[pgbouncer]
listen_port = 6432
listen_addr = localhost
auth_type = md5
auth_file = userlist.txt
logfile = pgbouncer.log
pidfile = pgbouncer.pid
admin_users = someuser
2. Create a userlist.txt file that contains the users allowed in:
"someuser" "same_password_as_in_server"
3. Launch pgbouncer:
$ pgbouncer -d pgbouncer.ini
4. Have your application (or the psql client) connect to pgbouncer instead of directly to
the PostgreSQL server:
$ psql -p 6432 -U someuser template1
5. Manage pgbouncer by connecting to the special administration database pgbouncer and
issuing SHOW HELP; to begin:
$ psql -p 6432 -U someuser pgbouncer
pgbouncer=# SHOW HELP;
NOTICE: Console usage
DETAIL:
SHOW [HELP|CONFIG|DATABASES|FDS|POOLS|CLIENTS|SERVERS|SOCKETS|LISTS|VERSION|...]
SET key = arg
RELOAD
PAUSE
SUSPEND
RESUME
SHUTDOWN
[...]
6. If you made changes to the pgbouncer.ini file, you can reload it with:
pgbouncer=# RELOAD;
COMMAND LINE SWITCHES
-d, --daemon
Run in the background. Without it, the process will run in the foreground.
In daemon mode, setting pidfile as well as logfile or syslog is required. No log
messages will be written to stderr after going into the background.
Note: Does not work on Windows; pgbouncer need to run as service there.
-R, --reboot
DEPRECATED: Instead of this option use a rolling restart with multiple pgbouncer
processes listening on the same port using so_reuseport instead Do an online
restart. That means connecting to the running process, loading the open sockets
from it, and then using them. If there is no active process, boot normally. Note:
Works only if OS supports Unix sockets and the unix_socket_dir is not disabled in
configuration. Does not work on Windows. Does not work with TLS connections, they
are dropped.
-u USERNAME, --user=USERNAME
Switch to the given user on startup.
-v, --verbose
Increase verbosity. Can be used multiple times.
-q, --quiet
Be quiet: do not log to stderr. This does not affect logging verbosity, only that
stderr is not to be used. For use in init.d scripts.
-V, --version
Show version.
-h, --help
Show short help.
--regservice
Win32: Register pgbouncer to run as Windows service. The service_name
configuration parameter value is used as the name to register under.
--unregservice
Win32: Unregister Windows service.
ADMIN CONSOLE
The console is available by connecting as normal to the database pgbouncer:
$ psql -p 6432 pgbouncer
Only users listed in the configuration parameters admin_users or stats_users are allowed
to log in to the console. (Except when auth_type=any, then any user is allowed in as a
stats_user.)
Additionally, the user name pgbouncer is allowed to log in without password, if the login
comes via the Unix socket and the client has same Unix user UID as the running process.
The admin console currently only supports the simple query protocol. Some drivers use the
extended query protocol for all commands; these drivers will not work for this.
Show commands
The SHOW commands output information. Each command is described below.
SHOW STATS
Shows statistics. In this and related commands, the total figures are since process
start, the averages are updated every stats_period.
database
Statistics are presented per database.
total_xact_count
Total number of SQL transactions pooled by pgbouncer.
total_query_count
Total number of SQL commands pooled by pgbouncer.
total_server_assignment_count
Total times a server was assigned to a client
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_xact_time
Total number of microseconds spent by pgbouncer when connected to PostgreSQL in a
transaction, either idle in transaction or executing queries.
total_query_time
Total number of microseconds spent by pgbouncer when actively connected to
PostgreSQL, executing queries.
total_wait_time
Time spent by clients waiting for a server, in microseconds. Updated when a client
connection is assigned a backend connection.
avg_xact_count
Average transactions per second in last stat period.
avg_query_count
Average queries per second in last stat period.
avg_server_assignment_count
Average number of times a server as assigned to a client per second in the last
stat period.
avg_recv
Average received (from clients) bytes per second.
avg_sent
Average sent (to clients) bytes per second.
avg_xact_time
Average transaction duration, in microseconds.
avg_query_time
Average query duration, in microseconds.
avg_wait_time
Time spent by clients waiting for a server, in microseconds (average of the wait
times for clients assigned a backend during the current stats_period).
SHOW STATS_TOTALS
Subset of SHOW STATS showing the total values (total_).
SHOW STATS_AVERAGES
Subset of SHOW STATS showing the average values (avg_).
SHOW TOTALS
Like SHOW STATS but aggregated across all databases.
SHOW SERVERS
type S, for server.
user User name pgbouncer uses to connect to server.
database
Database name.
replication
If server connection uses replication. Can be none, logical or physical.
state State of the pgbouncer server connection, one of active, idle, used, tested, new,
active_cancel, being_canceled.
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.
wait Not used for server connections.
wait_us
Not used for server connections.
close_needed
1 if the connection will be closed as soon as possible, because a configuration
file reload or DNS update changed the connection information or RECONNECT was
issued.
ptr Address of internal object for this connection. Used as unique ID.
link Address of client connection the server is paired with.
remote_pid
PID of backend server process. In case connection is made over Unix socket and OS
supports getting process ID info, its OS PID. Otherwise it’s extracted from cancel
packet the server sent, which should be the PID in case the server is PostgreSQL,
but it’s a random number in case the server it is another PgBouncer.
tls A string with TLS connection information, or empty if not using TLS.
application_name
A string containing the application_name set on the linked client connection, or
empty if this is not set, or if there is no linked connection.
prepared_statements
The amount of prepared statements that are prepared on the server. This number is
limited by the max_prepared_statements setting.
SHOW CLIENTS
type C, for client.
user Client connected user.
database
Database name.
replication
If client connection uses replication. Can be none, logical or physical.
state State of the client connection, one of active, waiting, active_cancel_req, or
waiting_cancel_req.
addr IP address of client.
port Source port of client.
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.
wait Current waiting time in seconds.
wait_us
Microsecond part of the current waiting time.
close_needed
not used for clients
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, in case client connects over Unix socket and OS supports getting it.
tls A string with TLS connection information, or empty if not using TLS.
application_name
A string containing the application_name set by the client for this connection, or
empty if this was not set.
prepared_statements
The amount of prepared statements that the client has prepared
SHOW POOLS
A new pool entry is made for each couple of (database, user).
database
Database name.
user User name.
cl_active
Client connections that are either linked to server connections or are idle with no
queries waiting to be processed.
cl_waiting
Client connections that have sent queries but have not yet got a server connection.
cl_active_cancel_req
Client connections that have forwarded query cancellations to the server and are
waiting for the server response.
cl_waiting_cancel_req
Client connections that have not forwarded query cancellations to the server yet.
sv_active
Server connections that are linked to a client.
sv_active_cancel
Server connections that are currently forwarding a cancel request.
sv_being_canceled
Servers that normally could become idle but are waiting to do so until all in-
flight cancel requests have completed that were sent to cancel a query on this
server.
sv_idle
Server connections that are unused and immediately usable for client queries.
sv_used
Server connections that have been idle for more than server_check_delay, so they
need server_check_query to run on them before they can be used again.
sv_tested
Server connections that are currently running either server_reset_query or
server_check_query.
sv_login
Server connections currently in the process of logging in.
maxwait
How long the first (oldest) client in the queue has waited, in seconds. If this
starts increasing, then the current pool of servers does not handle requests
quickly enough. The reason may be either an overloaded server or just too small of
a pool_size setting.
maxwait_us
Microsecond part of the maximum waiting time.
pool_mode
The pooling mode in use.
SHOW PEER_POOLS
A new peer_pool entry is made for each configured peer.
database
ID of the configured peer entry.
cl_active_cancel_req
Client connections that have forwarded query cancellations to the server and are
waiting for the server response.
cl_waiting_cancel_req
Client connections that have not forwarded query cancellations to the server yet.
sv_active_cancel
Server connections that are currently forwarding a cancel request.
sv_login
Server connections currently in the process of logging in.
SHOW LISTS
Show following internal information, in columns (not rows):
databases
Count of databases.
users Count of users.
pools Count of pools.
free_clients
Count of free clients. These are clients that are disconnected, but PgBouncer
keeps the memory around that was allocated for them so it can be reused for a
future clients to avoid allocations.
used_clients
Count of used clients.
login_clients
Count of clients in login state.
free_servers
Count of free servers. These are servers that are disconnected, but PgBouncer
keeps the memory around that was allocated for them so it can be reused for a
future servers to avoid allocations.
used_servers
Count of used servers.
dns_names
Count of DNS names in the cache.
dns_zones
Count of DNS zones in the cache.
dns_queries
Count of in-flight DNS queries.
dns_pending
not used
SHOW USERS
name The user name
pool_size
The user’s override pool_size. or NULL if not set.
pool_mode
The user’s override pool_mode, or NULL if not set.
max_user_connections
The user’s max_user_connections setting. If this setting is not set for this
specific user, then the default value will be displayed.
current_connections
Current number of connections that this user has open to all servers.
SHOW DATABASES
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 the user is part of the connection string, the connection between pgbouncer
and PostgreSQL is forced to the given user, whatever the client user.
pool_size
Maximum number of server connections.
min_pool_size
Minimum number of server connections.
reserve_pool
Maximum number of additional connections for this database.
server_lifetime
The maximum lifetime of a server connection for this database
pool_mode
The database’s override pool_mode, or NULL if the default will be used instead.
max_connections
Maximum number of allowed connections for this database, as set by
max_db_connections, either globally or per database.
current_connections
Current number of connections for this database.
paused 1 if this database is currently paused, else 0.
disabled
1 if this database is currently disabled, else 0.
SHOW PEERS
peer_id
ID of the configured peer entry.
host Host pgbouncer connects to.
port Port pgbouncer connects to.
pool_size
Maximum number of server connections that can be made to this peer
SHOW FDS
Internal command - shows list of file descriptors in use with internal state attached to
them.
When the connected user has the user name “pgbouncer”, connects through the Unix socket
and has same the UID as the running process, the actual FDs are passed over the
connection. This mechanism is used to do an online restart. Note: This does not work on
Windows.
This command also blocks the internal event loop, so it should not be used while PgBouncer
is in use.
fd File descriptor numeric value.
task One of pooler, client or server.
user User of the connection using the FD.
database
Database of the connection using the FD.
addr IP address of the connection using the FD, unix if a Unix socket is used.
port Port used by the connection using the FD.
cancel Cancel key for this connection.
link fd for corresponding server/client. NULL if idle.
SHOW SOCKETS, SHOW ACTIVE_SOCKETS
Shows low-level information about sockets or only active sockets. This includes the
information shown under SHOW CLIENTS and SHOW SERVERS as well as other more low-level
information.
SHOW CONFIG
Show the current configuration settings, one per row, with the following columns:
key Configuration variable name
value Configuration value
default
Configuration default value
changeable
Either yes or no, shows if the variable can be changed while running. If no, the
variable can be changed only at boot time. Use SET to change a variable at run
time.
SHOW MEM
Shows low-level information about the current sizes of various internal memory
allocations. The information presented is subject to change.
SHOW DNS_HOSTS
Show host names in DNS cache.
hostname
Host name.
ttl How many seconds until next lookup.
addrs Comma separated list of addresses.
SHOW DNS_ZONES
Show DNS zones in cache.
zonename
Zone name.
serial Current serial.
count Host names belonging to this zone.
SHOW VERSION
Show the PgBouncer version string.
SHOW STATE
Show the PgBouncer state settings. Current states are active, paused and suspended.
Process controlling commands
PAUSE [db]
PgBouncer tries to disconnect from all servers. Disconnecting each server connection
waits for that server connection to be released according to the server pool’s pooling
mode (in transaction pooling mode, the transaction must complete, in statement mode, the
statement must complete, and in session pooling mode the client must disconnect). The
command will not return before all server connections have been disconnected. To be used
at the time of database restart.
If database name is given, only that database will be paused.
New client connections to a paused database will wait until RESUME is called.
DISABLE db
Reject all new client connections on the given database.
ENABLE db
Allow new client connections after a previous DISABLE command.
RECONNECT [db]
Close each open server connection for the given database, or all databases, after it is
released (according to the pooling mode), even if its lifetime is not up yet. New server
connections can be made immediately and will connect as necessary according to the pool
size settings.
This command is useful when the server connection setup has changed, for example to
perform a gradual switchover to a new server. It is not necessary to run this command
when the connection string in pgbouncer.ini has been changed and reloaded (see RELOAD) or
when DNS resolution has changed, because then the equivalent of this command will be run
automatically. This command is only necessary if something downstream of PgBouncer routes
the connections.
After this command is run, there could be an extended period where some server connections
go to an old destination and some server connections go to a new destination. This is
likely only sensible when switching read-only traffic between read-only replicas, or when
switching between nodes of a multimaster replication setup. If all connections need to be
switched at the same time, PAUSE is recommended instead. To close server connections
without waiting (for example, in emergency failover rather than gradual switchover
scenarios), also consider KILL.
KILL db
Immediately drop all client and server connections on given database.
New client connections to a killed database will wait until RESUME is called.
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 at the time of PgBouncer
online reboot.
New client connections to a suspended database will wait until RESUME is called.
RESUME [db]
Resume work from previous KILL, PAUSE, or SUSPEND command.
SHUTDOWN
The PgBouncer process will exit.
SHUTDOWN WAIT_FOR_SERVERS
Stop accepting new connections and shutdown after all servers are released. This is
basically the same as issuing PAUSE and SHUTDOWN, except that this also stops accepting
new connections while waiting for the PAUSE as well as eagerly disconnecting clients that
are waiting to receive a server connection.
SHUTDOWN WAIT_FOR_CLIENTS
Stop accepting new connections and shutdown the process once all existing clients have
disconnected. This command can be used to do zero-downtime rolling restart of two
PgBouncer processes using the following procedure:
1. Have two or more PgBouncer processes running on the same port using so_reuseport
(configuring peering is recommended, but not required). To achieve zero downtime when
restarting we’ll restart these processes one-by-one, thus leaving the others running to
accept connections while one is being restarted.
2. Pick a process to restart first, let’s call it A.
3. Run SHUTDOWN WAIT_FOR_CLIENTS (or send SIGTERM) to process A.
4. Cause all clients to reconnect. Possibly by waiting some time until the client side
pooler causes reconnects due to its server_idle_timeout (or similar config). Or if no
client side pooler is used, possibly by restarting the clients. Once all clients have
reconnected. Process A will exit automatically, because no clients are connected to it
anymore.
5. Start process A again.
6. Repeat step 3, 4 and 5 for each of the remaining processes, one-by-one until you
restarted all processes.
RELOAD
The PgBouncer process will reload its configuration files and update changeable settings.
This includes the main configuration file as well as the files specified by the settings
auth_file and auth_hba_file.
PgBouncer notices when a configuration file reload changes the connection parameters of a
database definition. An existing server connection to the old destination will be closed
when the server connection is next released (according to the pooling mode), and new
server connections will immediately use the updated connection parameters.
WAIT_CLOSE [db]
Wait until all server connections, either of the specified database or of all databases,
have cleared the “close_needed” state (see SHOW SERVERS). This can be called after a
RECONNECT or RELOAD to wait until the respective configuration change has been fully
activated, for example in switchover scripts.
Other commands
SET key = arg
Changes a configuration setting (see also SHOW CONFIG). For example:
SET log_connections = 1;
SET server_check_query = 'select 2';
(Note that this command is run on the PgBouncer admin console and sets PgBouncer settings.
A SET command run on another database will be passed to the PostgreSQL backend like any
other SQL command.)
Signals
SIGHUP Reload config. Same as issuing the command RELOAD on the console.
SIGTERM
Super safe shutdown. Wait for all existing clients to disconnect, but don’t accept
new connections. This is the same as issuing SHUTDOWN WAIT_FOR_CLIENTS on the
console. If this signal is received while there is already a shutdown in progress,
then an “immediate shutdown” is triggered instead of a “super safe shutdown”. In
PgBouncer versions earlier than 1.23.0, this signal would cause an “immediate
shutdown”.
SIGINT Safe shutdown. Same as issuing SHUTDOWN WAIT_FOR_SERVERS on the console. If this
signal is received while there is already a shutdown in progress, then an
“immediate shutdown” is triggered instead of a “safe shutdown”.
SIGQUIT
Immediate shutdown. Same as issuing SHUTDOWN on the console.
SIGUSR1
Same as issuing PAUSE on the console.
SIGUSR2
Same as issuing RESUME on the console.
Libevent settings
From the Libevent documentation:
It is possible to disable support for epoll, kqueue, devpoll, poll or select by
setting the environment variable EVENT_NOEPOLL, EVENT_NOKQUEUE, EVENT_NODEVPOLL,
EVENT_NOPOLL or EVENT_NOSELECT, respectively.
By setting the environment variable EVENT_SHOW_METHOD, libevent displays the kernel
notification method that it uses.
SEE ALSO
pgbouncer(5) - man page of configuration settings descriptions
<https://www.pgbouncer.org/>