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PGBOUNCER(5) Databases PGBOUNCER(5)
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.
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/PgBouncer
1.7 2006-10-23 PGBOUNCER(5)