pgbouncer man page
pgbouncer — lightweight connection pooler for PostgreSQL
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>
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.
Basic setup and usage as following.
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
Create users.txt file that contains users allowed in:
$ pgbouncer -d pgbouncer.ini
Have your application (or the psql client) connect to pgbouncer instead of directly to PostgreSQL server:
$ psql -p 6543 -U someuser template1
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
If you made changes to the pgbouncer.ini file, you can reload it with:
Command Line Switches
Run in background. Without it the process will run in foreground. Note: Does not work on Windows, pgbouncer need to run as service there.
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.
Increase verbosity. Can be used multiple times.
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.
Show short help.
Win32: Register pgbouncer to run as Windows service. The service_name config parameter value is used as name to register under.
Win32: Unregister Windows service.
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.
The SHOW commands output information. Each command is described below.
Statistics are presented per database.
Total number of SQL requests pooled by pgbouncer.
Total volume in bytes of network traffic received by pgbouncer.
Total volume in bytes of network traffic sent by pgbouncer.
Total number of microseconds spent by pgbouncer when actively connected to PostgreSQL.
Average requests per second in last stat period.
Average received (from clients) bytes per second.
Average sent (to clients) bytes per second.
Average query duration in microseconds.
S, for server.
Username pgbouncer uses to connect to server.
State of the pgbouncer server connection, one of active, used or idle.
IP address of PostgreSQL server.
Port of PostgreSQL server.
Connection start address on local machine.
Connection start port on local machine.
When the connection was made.
When last request was issued.
Address of internal object for this connection. Used as unique ID.
Address of client connection the server is paired with.
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.
C, for client.
Client connected user.
State of the client connection, one of active, used, waiting or idle.
IP address of client.
Port client is connected to.
Connection end address on local machine.
Connection end port on local machine.
Timestamp of connect time.
Timestamp of latest client request.
Address of internal object for this connection. Used as unique ID.
Address of server connection the client is paired with.
Process ID, in case client connects over UNIX socket and OS supports getting it.
A new pool entry is made for each couple of (database, user).
Client connections that are linked to server connection and can process queries.
Client connections have sent queries but have not yet got a server connection.
Server connections that linked to client.
Server connections that unused and immediately usable for client queries.
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.
Server connections that are currently running either server_reset_query or server_check_query.
Server connections currently in logging in process.
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.
The pooling mode in use.
Show following internal information, in columns (not rows):
Count of databases.
Count of users.
Count of pools.
Count of free clients.
Count of used clients.
Count of clients in login state.
Count of free servers.
Count of used servers.
The user name
The user's override pool_mode, or NULL if the default will be used instead.
Name of configured database entry.
Host pgbouncer connects to.
Port pgbouncer connects to.
Actual database name pgbouncer connects to.
When user is part of the connection string, the connection between pgbouncer and PostgreSQL is forced to the given user, whatever the client user.
Maximum number of server connections.
The database's override pool_mode, or NULL if the default will be used instead.
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.
File descriptor numeric value.
One of pooler, client or server.
User of the connection using the FD.
Database of the connection using the FD.
IP address of the connection using the FD, unix if a unix socket is used.
Port used by the connection using the FD.
Cancel key for this connection.
fd for corresponding server/client. NULL if idle.
Show the current configuration settings, one per row, with following columns:
Configuration variable name
Either yes or no, shows if the variable can be changed while running. If no, the variable can be changed only boot-time.
Show hostnames in DNS cache.
How meny seconds until next lookup.
Comma separated list of addresses.
Show DNS zones in cache.
Hostnames belonging to this zone.
Process controlling commands
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.
Reject all new client connections on the given database.
Allow new client connections after a previous DISABLE command.
Immediately drop all client and server connections on given database.
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 work from previous PAUSE or SUSPEND command.
The PgBouncer process will exit.
The PgBouncer process will reload its configuration file and update changeable settings.
Reload config. Same as issuing command Reload; on console.
Safe shutdown. Same as issuing PAUSE; and Shutdown; on console.
Immediate shutdown. Same as issuing Shutdown; on console.
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.
pgbouncer(5) - manpage of configuration settings descriptions.