NAME
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.
-
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 a users.txt file:
"someuser" "same_password_as_in_server"
-
Launch
pgbouncer
:$ pgbouncer -d pgbouncer.ini
-
Have your application (or the
psql
client) connect topgbouncer
instead of directly to PostgreSQL server.$ psql -p 6543 -U someuser template1
-
Manage
pgbouncer
by connecting to the special administration databasepgbouncer
and issuingshow 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:
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. - -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 an admin.)
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 bypgbouncer
. - 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
oridle
. - 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.
SHOW CLIENTS;
- type
-
C, for client.
- user
-
Client connected user.
- database
-
Database name.
- state
-
State of the client connection, one of
active
,used
,waiting
oridle
. - 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.
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 needsserver_check_query
to run on it before it can be used. - sv_tested
-
Server connections that are currently running either
server_reset_query
orserver_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.
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;
Shows one line per user, under the name
column name.
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.
SHOW FDS;
Shows list of fds in use. 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.
- fd
-
File descriptor numeric value.
- task
-
One of
pooler
,client
orserver
. - 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
orno
, shows if the variable can be changed while running. Ifno
, 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.
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;
andSHUTDOWN;
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.