pgbouncer man page

pgbouncer — lightweight connection pooler for PostgreSQL

Synopsis

pgbouncer [-d][-R][-v][-u user] <pgbouncer.ini>
pgbouncer -V|-h

On Windows computers, 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 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 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 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 as following.

1.

Create a pgbouncer.ini file. Details in pgbouncer(5). Simple example:

[databases]
template1 = host=127.0.0.1 port=5432 dbname=template1

[pgbouncer]
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
2.

Create users.txt file that contains 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 PostgreSQL server:

$ psql -p 6543 -U someuser template1
5.

Manage pgbouncer by connecting to the special administration database pgbouncer and issuing show help; to begin:

$ psql -p 6543 -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
Run in background. Without it the process will run in foreground. Note: Does not work on Windows, pgbouncer need to run as service there.
-R
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 config. Does not work on Windows machines. Does not work with TLS connections, they are dropped.
-u user
Switch to the given user on startup.
-v
Increase verbosity. Can be used multiple times.
-q
Be quiet - do not log to stdout. Note this does not affect logging verbosity, only that stdout is not to be used. For use in init.d scripts.
-V
Show version.
-h
Show short help.
--regservice
Win32: Register pgbouncer to run as Windows service. The service_name config parameter value is used as 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 6543 pgbouncer

Only users listed in configuration parameters admin_users or stats_users are allowed to login to the console. (Except when auth_mode=any, then any user is allowed in as a stats_user.)

Additionally, the username pgbouncer is allowed to log in without password, if the login comes via Unix socket and the client has same Unix user uid as the running process.

Show commands

The SHOW commands output information. Each command is described below.

Show Stats;

Shows statistics.

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 PostgreSQL.
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.

Show Servers;

type
S, for server.
user
Username 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 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.
remote_pid
Pid of backend server process. In case connection is made over unix socket and OS supports getting process ID info, it's OS pid. Otherwise it's extracted from cancel packet server sent, which should be PID in case server is Postgres, but it's a random number in case server it another PgBouncer.

Show Clients;

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.
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, in case client connects over UNIX socket and OS supports getting it.

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 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 unused and immediately usable for client queries.
sv_used
Server connections that have been idle more than server_check_delay, so they needs server_check_query to run on it before it 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 logging in process.
maxwait
How long the first (oldest) client in queue has waited, in seconds. If this starts increasing, then the current pool of servers does not handle requests quick enough. Reason may be either overloaded server or just too small of a pool_size setting.
pool_mode
The pooling mode in use.

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.
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.

Show Users;

name
The user name
pool_mode
The user's override pool_mode, or NULL if the default will be used instead.

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 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.
pool_mode
The database's override pool_mode, or NULL if the default will be used instead.

Show Fds;

Internal command - shows list of fds in use with internal state attached to them.

When the connected user has username "pgbouncer", connects through Unix socket and has same UID as 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 machines.

This command also blocks 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 Config;

Show the current configuration settings, one per row, with following columns:

key
Configuration variable name
value
Configuration value
changeable
Either yes or no, shows if the variable can be changed while running. If no, the variable can be changed only boot-time.

Show Dns_hosts;

Show hostnames in DNS cache.

hostname
Host name.
ttl
How meny 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
Hostnames belonging to this zone.

Process controlling commands

PAUSE [db];

PgBouncer tries to disconnect from all servers, first waiting for all queries to complete. The command will not return before all queries are finished. To be used at the time of database restart.

If database name is given, only that database will be paused.

DISABLE db;

Reject all new client connections on the given database.

ENABLE db;

Allow new client connections after a previous DISABLE command.

KILL db;

Immediately drop all client and server connections on given 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 at the time of PgBouncer online reboot.

RESUME [db];

Resume work from previous PAUSE or SUSPEND command.

Shutdown;

The PgBouncer process will exit.

Reload;

The PgBouncer process will reload its configuration file and update changeable settings.

Signals

SIGHUP
Reload config. Same as issuing command Reload; on console.
SIGINT
Safe shutdown. Same as issuing PAUSE; and Shutdown; on console.
SIGTERM
Immediate shutdown. Same as issuing Shutdown; on console.

Libevent settings

From libevent docs:

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) - manpage of configuration settings descriptions.

https://pgbouncer.github.io/

https://wiki.postgresql.org/wiki/PgBoun…

Referenced By

pgbouncer(5).

2006-10-23 1.7 Databases