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>
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:
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.
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.
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”
Basic setup and usage is as follows.
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 = 6432 listen_addr = 127.0.0.1 auth_type = md5 auth_file = userlist.txt logfile = pgbouncer.log pidfile = pgbouncer.pid admin_users = someuser
userlist.txt file that contains the users allowed in:
$ pgbouncer -d pgbouncer.ini
Have your application (or the psql client) connect to pgbouncer instead of directly to the PostgreSQL server:
$ psql -p 6432 -U someuser template1
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 [...]
If you made changes to the pgbouncer.ini file, you can reload it with:
unix_socket_diris not disabled in configuration. Does not work on Windows. Does not work with TLS connections, they are dropped.
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
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 SHOW commands output information. Each command is described below.
Shows statistics. In this and related commands, the total figures are
since process start, the averages are updated every
Subset of SHOW STATS showing the total values (total_).
Subset of SHOW STATS showing the average values (avg_).
Like SHOW STATS but aggregated across all databases.
A new pool entry is made for each couple of (database, user).
server_check_delay, so they need
server_check_queryto run on them before they can be used again.
Show following internal information, in columns (not rows):
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.
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 the current configuration settings, one per row, with the following columns:
Shows low-level information about the current sizes of various internal memory allocations. The information presented is subject to change.
Show host names in DNS cache.
Show DNS zones in cache.
Show the PgBouncer version string.
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.
New client connections to a paused database will wait until RESUME is called.
Reject all new client connections on the given database.
Allow new client connections after a previous DISABLE command.
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.
Immediately drop all client and server connections on given database.
New client connections to a killed database will wait until RESUME is called.
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 work from previous KILL, PAUSE, or SUSPEND command.
The PgBouncer process will exit.
The PgBouncer process will reload its configuration file and update changeable settings.
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 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.
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.)
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.
pgbouncer(5) - man page of configuration settings descriptions