--- name: "pgbouncer" section: "1" platform: "linux" package: "pgbouncer" version: "1.26.0-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/pgbouncer" --- # pgbouncer(1) lightweight connection pooler for PostgreSQL ## NAME pgbouncer - lightweight connection pooler for PostgreSQL ## SYNOPSIS - ``` pgbouncer [-d][-v][-u user] pgbouncer -V|-h ``` On Windows, the options are: - ``` pgbouncer.exe [-v][-u user] pgbouncer.exe -V|-h ``` Additional options for setting up a Windows service: - ``` pgbouncer.exe --regservice pgbouncer.exe --unregservice ``` ## 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 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. - Transaction pooling 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. - 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` commands 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)](/pgbouncer/5.md)**. 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|POOLS|CLIENTS|SERVERS|SOCKETS|LISTS|VERSION|...] SET key = arg RELOAD PAUSE 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 required. 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. - `-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 verbosity, 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 **service\_name** configuration parameter value is used as the 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 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 password, 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 connected to PostgreSQL, executing queries. - total\_wait\_time Time spent by clients waiting for a server, in microseconds. Updated when a client connection is assigned a backend connection. - total\_client\_parse\_count Total number of prepared statements created by clients. Only applicable in named prepared statement tracking mode, see `max_prepared_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`. - total\_client\_login\_count Total number of successful client logins. - 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 applicable in named prepared statement tracking mode, see `max_prepared_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_statements`. - avg\_client\_login\_count Average number of successful client logins per second. ### 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 information 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. Otherwise 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 number 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\_cancel\_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 until 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_reset_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 seconds. 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. - peer\_id 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 displayed. - current\_client\_connections Current number of client connections that this user has open to PgBouncer. ### 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 between 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-separated 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 instance, 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 SOCKETS, SHOW ACTIVE\_SOCKETS 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 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 running. 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 and paused. ### 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 session 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* 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**. ### 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 connections 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`. ### RESUME \[db\] Resume work from previous **KILL** or **PAUSE** 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 connection. 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 immediately 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 PgBouncer 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 **SHUTDOWN 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 PgBouncer 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 shutdown 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, respectively. By setting the environment variable EVENT\_SHOW\_METHOD, libevent displays the kernel notification method that it uses. ## SEE ALSO [pgbouncer(5)](/pgbouncer/5.md) - man page of configuration settings descriptions ⟨https://www.pgbouncer.org/⟩\\c