PGBOUNCER(1) Databases PGBOUNCER(1) NAME pgbouncer - lightweight connection pooler for PostgreSQL SYNOPSIS 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> 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 con- nections 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 a client connects, a server connection will be assigned to it for the whole duration the client stays con- nected. 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 a client only during a transac- tion. 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 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 com- mands available when connected to a special "virtual" database pgbouncer. QUICK-START Basic setup and usage is as follows. 1. Create a pgbouncer.ini file. Details in pgbouncer(5). Simple example: [databases] template1 = host=localhost port=5432 dbname=template1 [pgbouncer] listen_port = 6432 listen_addr = localhost auth_type = md5 auth_file = userlist.txt logfile = pgbouncer.log pidfile = pgbouncer.pid admin_users = someuser 2. Create a userlist.txt file that contains the 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 the PostgreSQL server: $ psql -p 6432 -U someuser template1 5. 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 [...] 6. If you made changes to the pgbouncer.ini file, you can reload it with: pgbouncer=# RELOAD; COMMAND LINE SWITCHES -d, --daemon Run in the background. Without it, the process will run in the foreground. In daemon mode, setting pidfile as well as logfile or syslog is re- quired. No log messages will be written to stderr after going into the background. Note: Does not work on Windows; pgbouncer need to run as service there. -R, --reboot DEPRECATED: Instead of this option use a rolling restart with multi- ple pgbouncer processes listening on the same port using so_reuse- port instead 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 dis- abled in configuration. Does not work on Windows. Does not work with TLS connections, they are dropped. -u USERNAME, --user=USERNAME Switch to the given user on startup. -v, --verbose Increase verbosity. Can be used multiple times. -q, --quiet Be quiet: do not log to stderr. This does not affect logging ver- bosity, only that stderr is not to be used. For use in init.d scripts. -V, --version Show version. -h, --help Show short help. --regservice Win32: Register PgBouncer to run as Windows service. The ser- vice_name configuration parameter value is used as the name to reg- ister under. --unregservice Win32: Unregister Windows service. ADMIN CONSOLE 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 auth_type=any, then any user is allowed in as a stats_user.) Additionally, the user name pgbouncer is allowed to log in without pass- word, if the login comes via the Unix socket and the client has same Unix user UID as the running process. The admin console currently only supports the simple query protocol. Some drivers use the extended query protocol for all commands; these drivers will not work for this. Show commands The SHOW commands output information. Each command is described below. SHOW STATS Shows statistics. In this and related commands, the total figures are since process start, the averages are updated every stats_period. database Statistics are presented per database. total_xact_count Total number of SQL transactions pooled by pgbouncer. total_query_count Total number of SQL commands pooled by pgbouncer. total_server_assignment_count Total times a server was assigned to a client 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_xact_time Total number of microseconds spent by pgbouncer when connected to PostgreSQL in a transaction, either idle in transaction or executing queries. total_query_time Total number of microseconds spent by pgbouncer when actively con- nected to PostgreSQL, executing queries. total_wait_time Time spent by clients waiting for a server, in microseconds. Up- dated when a client connection is assigned a backend connection. total_client_parse_count Total number of prepared statements created by clients. Only ap- plicable in named prepared statement tracking mode, see max_pre- pared_statements. total_server_parse_count Total number of prepared statements created by pgbouncer on a server. Only applicable in named prepared statement tracking mode, see max_prepared_statements. total_bind_count Total number of prepared statements readied for execution by clients and forwarded to PostgreSQL by pgbouncer. Only applicable in named prepared statement tracking mode, see max_prepared_statements. avg_xact_count Average transactions per second in last stat period. avg_query_count Average queries per second in last stat period. avg_server_assignment_count Average number of times a server as assigned to a client per second in the last stat period. avg_recv Average received (from clients) bytes per second. avg_sent Average sent (to clients) bytes per second. avg_xact_time Average transaction duration, in microseconds. avg_query_time Average query duration, in microseconds. avg_wait_time Time spent by clients waiting for a server, in microseconds (average of the wait times for clients assigned a backend during the current stats_period). avg_client_parse_count Average number of prepared statements created by clients. Only ap- plicable in named prepared statement tracking mode, see max_pre- pared_statements. avg_server_parse_count Average number of prepared statements created by pgbouncer on a server. Only applicable in named prepared statement tracking mode, see max_prepared_statements. avg_bind_count Average number of prepared statements readied for execution by clients and forwarded to PostgreSQL by pgbouncer. Only applicable in named prepared statement tracking mode, see max_prepared_state- ments. SHOW STATS_TOTALS Subset of SHOW STATS showing the total values (total_). SHOW STATS_AVERAGES Subset of SHOW STATS showing the average values (avg_). SHOW TOTALS Like SHOW STATS but aggregated across all databases. SHOW SERVERS type S, for server. user User name pgbouncer uses to connect to server. database Database name. replication If server connection uses replication. Can be none, logical or physical. state State of the PgBouncer server connection, one of active, idle, used, tested, new, active_cancel, being_canceled. 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. wait Not used for server connections. wait_us Not used for server connections. close_needed 1 if the connection will be closed as soon as possible, because a configuration file reload or DNS update changed the connection in- formation or RECONNECT was issued. ptr Address of internal object for this connection. 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, its OS PID. Other- wise it's extracted from cancel packet the server sent, which should be the PID in case the server is PostgreSQL, but it's a random num- ber in case the server it is another PgBouncer. tls A string with TLS connection information, or empty if not using TLS. application_name A string containing the application_name set on the linked client connection, or empty if this is not set, or if there is no linked connection. prepared_statements The amount of prepared statements that are prepared on the server. This number is limited by the max_prepared_statements setting. id Unique ID for server. SHOW CLIENTS type C, for client. user Client connected user. database Database name. replication If client connection uses replication. Can be none, logical or physical. state State of the client connection, one of active (Client connections that are linked to server connections), idle (Client connections with no queries waiting to be processed), waiting, active_can- cel_req, or waiting_cancel_req. addr IP address of client. port Source port of client. 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. wait Current waiting time in seconds. wait_us Microsecond part of the current waiting time. close_needed not used for clients ptr Address of internal object for this connection. 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. tls A string with TLS connection information, or empty if not using TLS. application_name A string containing the application_name set by the client for this connection, or empty if this was not set. prepared_statements The amount of prepared statements that the client has prepared id Unique ID for client. 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 either linked to server connections or are idle with no queries waiting to be processed. cl_waiting Client connections that have sent queries but have not yet got a server connection. cl_active_cancel_req Client connections that have forwarded query cancellations to the server and are waiting for the server response. cl_waiting_cancel_req Client connections that have not forwarded query cancellations to the server yet. sv_active Server connections that are linked to a client. sv_active_cancel Server connections that are currently forwarding a cancel request. sv_being_canceled Servers that normally could become idle but are waiting to do so un- til all in-flight cancel requests have completed that were sent to cancel a query on this server. sv_idle Server connections that are unused and immediately usable for client queries. sv_used Server connections that have been idle for more than server_check_delay, so they need server_check_query to run on them before they can be used again. sv_tested Server connections that are currently running either server_re- set_query or server_check_query. sv_login Server connections currently in the process of logging in. maxwait How long the first (oldest) client in the queue has waited, in sec- onds. If this starts increasing, then the current pool of servers does not handle requests quickly enough. The reason may be either an overloaded server or just too small of a pool_size setting. maxwait_us Microsecond part of the maximum waiting time. pool_mode The pooling mode in use. load_balance_hosts The load_balance_hosts in use if the pool's host contains a comma-separated list. SHOW PEER_POOLS A new peer_pool entry is made for each configured peer. database ID of the configured peer entry. cl_active_cancel_req Client connections that have forwarded query cancellations to the server and are waiting for the server response. cl_waiting_cancel_req Client connections that have not forwarded query cancellations to the server yet. sv_active_cancel Server connections that are currently forwarding a cancel request. sv_login Server connections currently in the process of logging in. 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. These are clients that are disconnected, but PgBouncer keeps the memory around that was allocated for them so it can be reused for a future clients to avoid allocations. used_clients Count of used clients. login_clients Count of clients in login state. free_servers Count of free servers. These are servers that are disconnected, but PgBouncer keeps the memory around that was allocated for them so it can be reused for a future servers to avoid allocations. used_servers Count of used servers. dns_names Count of DNS names in the cache. dns_zones Count of DNS zones in the cache. dns_queries Count of in-flight DNS queries. dns_pending not used SHOW USERS name The user name pool_size The user's override pool_size. or NULL if not set. reserve_pool_size The user's override reserve_pool_size. or NULL if not set. pool_mode The user's override pool_mode, or NULL if not set. max_user_connections The user's max_user_connections setting. If this setting is not set for this specific user, then the default value will be displayed. current_connections Current number of server connections that this user has open to all servers. max_user_client_connections The user's max_user_client_connections setting. If this setting is not set for this specific user, then the default value will be dis- played. current_client_connections Current number of client connections that this user has open to Pg- Bouncer. 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 the user is part of the connection string, the connection be- tween PgBouncer and PostgreSQL is forced to the given user, whatever the client user. pool_size Maximum number of server connections. min_pool_size Minimum number of server connections. reserve_pool_size Maximum number of additional connections for this database. server_lifetime The maximum lifetime of a server connection for this database pool_mode The database's override pool_mode, or NULL if the default will be used instead. load_balance_hosts The database's load_balance_hosts if the host contains a comma-sepa- rated list. max_connections Maximum number of allowed server connections for this database, as set by max_db_connections, either globally or per database. current_connections Current number of server connections for this database. max_client_connections Maximum number of allowed client connections for this PgBouncer in- stance, as set by max_db_client_connections per database. current_client_connections Current number of client connections for this database. paused 1 if this database is currently paused, else 0. disabled 1 if this database is currently disabled, else 0. SHOW PEERS peer_id ID of the configured peer entry. host Host PgBouncer connects to. port Port PgBouncer connects to. pool_size Maximum number of server connections that can be made to this peer SHOW FDS 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. 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 SOCKETS, SHOW ACTIVE_SOCKETS Shows low-level information about sockets or only active sockets. This in- cludes the information shown under SHOW CLIENTS and SHOW SERVERS as well as other more low-level information. SHOW CONFIG Show the current configuration settings, one per row, with the following columns: key Configuration variable name value Configuration value default Configuration default value changeable Either yes or no, shows if the variable can be changed while run- ning. If no, the variable can be changed only at boot time. Use SET to change a variable at run time. SHOW MEM Shows low-level information about the current sizes of various internal memory allocations. The information presented is subject to change. SHOW DNS_HOSTS Show host names in DNS cache. hostname Host name. ttl How many 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 Host names belonging to this zone. SHOW VERSION Show the PgBouncer version string. SHOW STATE Show the PgBouncer state settings. Current states are active, paused and suspended. Process controlling commands PAUSE [db] PgBouncer tries to disconnect from all servers. Disconnecting each server connection waits for that server connection to be released according to the server pool's pooling mode (in transaction pooling mode, the transaction must complete, in statement mode, the statement must complete, and in ses- sion pooling mode the client must disconnect). The command will not return before all server connections have been disconnected. 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. DISABLE db Reject all new client connections on the given database. ENABLE db Allow new client connections after a previous DISABLE command. RECONNECT [db] 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 neces- sary 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. KILL [db] Immediately drop all client and server connections on the given database or all databases, excluding the admin database. New client connections to a killed database will wait until RESUME is called. KILL_CLIENT id Immediately kill specified client connection along with any server connec- tions for the given client. The client to kill, is identified by the id value that can be found using the SHOW CLIENTS command. An example command will look something like KILL_CLIENT 1234. 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. New client connections to a suspended database will wait until RESUME is called. RESUME [db] Resume work from previous KILL, PAUSE, or SUSPEND command. SHUTDOWN The PgBouncer process will exit. SHUTDOWN WAIT_FOR_SERVERS Stop accepting new connections and shutdown after all servers are released. This is basically the same as issuing PAUSE and SHUTDOWN, except that this also stops accepting new connections while waiting for the PAUSE as well as eagerly disconnecting clients that are waiting to receive a server connec- tion. Please note that UNIX sockets will remain open during the shutdown but will only accept connections to the PgBouncer admin console. SHUTDOWN WAIT_FOR_CLIENTS Stop accepting new connections and shutdown the process once all existing clients have disconnected. Please note that UNIX sockets will remain open during the shutdown but will only accept connections to the pgbouncer admin console. This command can be used to do zero-downtime rolling restart of two PgBouncer processes using the following procedure: 1. Have two or more PgBouncer processes running on the same port using so_reuseport (configuring peering is recommended, but not required). To achieve zero downtime when restarting we'll restart these processes one-by-one, thus leaving the others running to accept connections while one is being restarted. 2. Pick a process to restart first, let's call it A. 3. Run SHUTDOWN WAIT_FOR_CLIENTS (or send SIGTERM) to process A. 4. Cause all clients to reconnect. Possibly by waiting some time until the client side pooler causes reconnects due to its server_idle_timeout (or similar config). Or if no client side pooler is used, possibly by restarting the clients. Once all clients have reconnected. Process A will exit automatically, because no clients are connected to it anymore. 5. Start process A again. 6. Repeat step 3, 4 and 5 for each of the remaining processes, one-by-one until you restarted all processes. RELOAD The PgBouncer process will reload its configuration files and update changeable settings. This includes the main configuration file as well as the files specified by the settings auth_file and auth_hba_file. 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 immedi- ately use the updated connection parameters. WAIT_CLOSE [db] 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. Other commands SET key = arg 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 Pg- Bouncer settings. A SET command run on another database will be passed to the PostgreSQL backend like any other SQL command.) Signals SIGHUP Reload config. Same as issuing the command RELOAD on the console. SIGTERM Super safe shutdown. Wait for all existing clients to disconnect, but don't accept new connections. This is the same as issuing SHUT- DOWN WAIT_FOR_CLIENTS on the console. If this signal is received while there is already a shutdown in progress, then an "immediate shutdown" is triggered instead of a "super safe shutdown". In Pg- Bouncer versions earlier than 1.23.0, this signal would cause an "immediate shutdown". SIGINT Safe shutdown. Same as issuing SHUTDOWN WAIT_FOR_SERVERS on the console. If this signal is received while there is already a shut- down in progress, then an "immediate shutdown" is triggered instead of a "safe shutdown". SIGQUIT Immediate shutdown. Same as issuing SHUTDOWN on the console. SIGUSR1 Same as issuing PAUSE on the console. SIGUSR2 Same as issuing RESUME on the console. Libevent settings 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, re- spectively. By setting the environment variable EVENT_SHOW_METHOD, libevent dis- plays the kernel notification method that it uses. SEE ALSO pgbouncer(5) - man page of configuration settings descriptions https://www.pgbouncer.org/ 1.25.1 PGBOUNCER(1)
NAME | SYNOPSIS | DESCRIPTION | QUICK-START | COMMAND LINE SWITCHES | ADMIN CONSOLE | SEE ALSO
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