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 a users.txt file:
"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: 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 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.
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.
SHOW POOLS;
A new pool entry is made for each couple of (database, user).
database
Database name.
user
Username.
cl_active
Count of currently active client connections.
cl_waiting
Count of currently waiting client connections.
sv_active
Count of currently active server connections.
sv_idle
Count of currently idle server connections.
sv_used
Count of currently used server connections.
sv_tested
Count of currently tested server connections.
sv_login
Count of server connections currently logged in to PostgreSQL.
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 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.
PROCESS CONTROLLING COMMANDS
PAUSE;
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.
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;
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.
http://pgbouncer.projects.postgresql.org/doc/
https://developer.skype.com/SkypeGarage/DbProjects/PgBouncer
05/17/2010