Pgpool-II

https://www.pgpool.net/docs/latest/en/html/
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Pgpool-II is a middleware that provides connection pooling, load balancing, and high availability...
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### Run pgpool_setup Utility

Source: https://www.pgpool.net/docs/latest/en/html/tutorial-replication.html

Execute the pgpool_setup utility to create a Pgpool-II installation with streaming replication mode, a primary PostgreSQL installation, and an async standby PostgreSQL installation. Ensure the current directory is empty before running.

```bash
pgpool_setup
```

--------------------------------

### Install Pgpool-II from source

Source: https://www.pgpool.net/docs/latest/en/html/example-basic.html

Standard commands to compile and install Pgpool-II from a source distribution.

```bash
     $ ./configure
     $ make
     $ make install
```

--------------------------------

### Install Pgpool-II

Source: https://www.pgpool.net/docs/latest/en/html/install-pgpool.html

Install the compiled binaries. Use gmake on Solaris or FreeBSD.

```bash
make install
```

--------------------------------

### Build and install pgpool-regclass

Source: https://www.pgpool.net/docs/latest/en/html/install-pgpool-regclass.html

Compile and install the extension from the source directory.

```bash
$ cd pgpool-II-4.7.1/src/sql/pgpool-regclass
$ make
$ make install
```

--------------------------------

### Start PostgreSQL Server

Source: https://www.pgpool.net/docs/latest/en/html/example-replication-mode.html

Start the PostgreSQL server using the pg_ctl command.

```bash
[server1]$ /usr/pgsql-18/bin/pg_ctl start
  
```

--------------------------------

### Example Route Table Command Configuration

Source: https://www.pgpool.net/docs/latest/en/html/example-aws.html

Concrete example of if_up_cmd and if_down_cmd settings using specific paths and route table IDs.

```text
if_up_cmd = '/etc/pgpool-II/aws_rtb_if_cmd.sh up $_IP_$ eth0 rtb-012345abcd,rtb-67890abcd /usr/local/bin/aws'
if_down_cmd = '/etc/pgpool-II/aws_rtb_if_cmd.sh down $_IP_$ eth0 rtb-012345abcd,rtb-67890abcd /usr/local/bin/aws'
```

--------------------------------

### Compile and install pgpool_recovery

Source: https://www.pgpool.net/docs/latest/en/html/install-pgpool-recovery.html

Build and install the extension from the source directory.

```bash
$ cd pgpool-II-4.7.1/src/sql/pgpool-recovery
$ make
$ make install
```

--------------------------------

### Starting Pgpool-II Server

Source: https://www.pgpool.net/docs/latest/en/html/pgpool.html

Options specific to starting the Pgpool-II main server.

```APIDOC
## Starting Pgpool-II Server

### Description
Options specific to starting the Pgpool-II main server.

### Options
- `-d` or `--debug`
  Run Pgpool-II in debug mode. Produces extensive debug messages.
- `-n` or `--dont-detach`
  Do not run in daemon mode; does not detach control ttys.
- `-x` or `--debug-assertions`
  Turns on various assertion checks, which is a debugging aid.
- `-C` or `--clear-oidmaps`
  Clear query cache oidmaps when `memqcache_method` is `memcached`. If `memqcache_method` is `shmem`, Pgpool-II always discards oidmaps at startup, so this option is not necessary.
- `-D` or `--discard-status`
  Discard the `pgpool_status` file and do not restore the previous status.
  **Caution**: This option is for developer testing purposes only. Using it may lead to split-brain scenarios if `pgpool_status` is accidentally removed.
```

--------------------------------

### Start Pgpool-II Service

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Start the Pgpool-II service on all configured servers using systemctl.

```bash
[all servers]# systemctl start pgpool.service
```

--------------------------------

### Start Pgpool-II System

Source: https://www.pgpool.net/docs/latest/en/html/watchdog-setup.html

Executes the startall script to initialize the Pgpool-II system components.

```bash
$ ls
pgpool0  pgpool1  pgpool2  shutdownall	startall

$ sh startall
waiting for server to start....16123 2016-08-18 16:26:53 JST LOG:  redirecting log output to logging collector process
16123 2016-08-18 16:26:53 JST HINT:  Future log output will appear in directory "pg_log".
done
server started
waiting for server to start....16136 2016-08-18 16:26:54 JST LOG:  redirecting log output to logging collector process
16136 2016-08-18 16:26:54 JST HINT:  Future log output will appear in directory "pg_log".
done
server started
```

--------------------------------

### Start Pgpool-II Service

Source: https://www.pgpool.net/docs/latest/en/html/install-rpm.html

Start the Pgpool-II service. Ensure that PostgreSQL servers are started before starting Pgpool-II.

```shell
systemctl start pgpool.service
```

--------------------------------

### Start PostgreSQL Primary Server

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Start the PostgreSQL service on the primary server using pg_ctl.

```bash
[postgres@server1 ~]$ /usr/pgsql-18/bin/pg_ctl start
    
```

--------------------------------

### Failover Command Example

Source: https://www.pgpool.net/docs/latest/en/html/runtime-config-failover.html

This is a pseudocode example illustrating how the `follow_primary_command` is executed after a primary node failover. It shows the logic for setting down node status and executing the command in a child process.

```pseudocode
for each backend node
{
    if (the node is not the new primary)
        set down node status to shared memory status
        memorize that follow primary command is needed to execute
}
if (we need to executed follow primary command)
{
    fork a child process
    (within the child process)

    for each backend node
    {
        if (the node status in shared memory is down)
            execute follow primary command
    }
}
```

--------------------------------

### Example Session Output

Source: https://www.pgpool.net/docs/latest/en/html/sql-show-pool-version.html

Sample output showing the result of the SHOW POOL_VERSION command.

```sql
    test=# show pool_version;
    pool_version
    --------------------------
    3.6.0 (subaruboshi)
    (1 row)
```

--------------------------------

### Install Pgpool-II Debug and Devel Packages

Source: https://www.pgpool.net/docs/latest/en/html/install-rpm.html

Optionally install debuginfo and development header files for Pgpool-II.

```shell
dnf install pgpool-II-pg18-debuginfo pgpool-II-pg18-devel
```

--------------------------------

### Start All Services

Source: https://www.pgpool.net/docs/latest/en/html/tutorial-replication.html

Start all components of the Pgpool-II and PostgreSQL cluster. This command initiates the primary and standby PostgreSQL servers and Pgpool-II.

```bash
./startall
```

--------------------------------

### Start PostgreSQL Primary Server

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Start the PostgreSQL primary server using pg_ctl. Ensure the postgres user context is used.

```bash
[root@server1 ~]# su - postgres -c "/usr/pgsql-18/bin/pg_ctl start"
```

--------------------------------

### Example Output of SHOW POOL_PROCESSES

Source: https://www.pgpool.net/docs/latest/en/html/sql-show-pool-processes.html

A sample output showing the status of various Pgpool-II processes.

```text
test=# show pool_processes;
 pool_pid |                      start_time                      | client_connection_count | database | username | backend_connection_time | pool_counter |       status
----------+------------------------------------------------------+-------------------------+----------+----------+-------------------------+--------------+---------------------
 32641    | 2021-09-28 04:40:45                                  | 0                       |          |          |                         |              | Wait for connection
 32642    | 2021-09-28 04:40:45                                  | 0                       |          |          |                         |              | Wait for connection
 32643    | 2021-09-28 04:40:45                                  | 0                       | test     | kawamoto | 2021-09-28 04:40:48     | 1            | Idle
 32644    | 2021-09-28 04:40:45                                  | 0                       | test     | kawamoto | 2021-09-28 04:43:15     | 1            | Execute command
 32645    | 2021-09-28 04:40:45                                  | 0                       |          |          |                         |              | Wait for connection
 32646    | 2021-09-28 04:40:45                                  | 0                       |          |          |                         |              | Wait for connection
 32647    | 2021-09-28 04:40:45                                  | 0                       |          |          |                         |              | Wait for connection
 32648    | 2021-09-28 04:40:45 (3:15 before process restarting) | 2                       |          |          |                         |              | Wait for connection
(8 rows)
```

--------------------------------

### Heartbeat Configuration Example

Source: https://www.pgpool.net/docs/latest/en/html/runtime-watchdog-config.html

Example configuration for heartbeat_hostname, heartbeat_port, and heartbeat_device for three Pgpool nodes. This is applicable when wd_lifecheck_method is set to 'heartbeat'.

```properties
heartbeat_hostname0 = 'server1'
heartbeat_port0 = 9694
heartbeat_device0 = ''

heartbeat_hostname1 = 'server2'
heartbeat_port1 = 9694
heartbeat_device1 = ''

heartbeat_hostname2 = 'server3'
heartbeat_port2 = 9694
heartbeat_device2 = ''
```

--------------------------------

### Start Pgpool-II Process

Source: https://www.pgpool.net/docs/latest/en/html/example-basic.html

Commands to launch the Pgpool-II service in various modes.

```bash
     $ pgpool
```

```bash
     $ pgpool -n &
```

```bash
     $ pgpool -n -d > /tmp/pgpool.log 2>&1 &
```

--------------------------------

### Start Pgpool-II Server

Source: https://www.pgpool.net/docs/latest/en/html/server-start.html

Execute this command to start the Pgpool-II server in the background. Specify the paths to the main pgpool configuration file and the pcp server configuration file using the -f and -F flags respectively.

```bash
$ `pgpool -f /usr/local/etc/pgpool.conf -F /usr/local/etc/pcp.conf`
```

--------------------------------

### Configure YUM Repository Exclusions

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Example configuration to prevent Pgpool-II from being installed via the PostgreSQL repository.

```ini
[pgdg-common]
...
exclude=pgpool*

[pgdg18]
...
exclude=pgpool*

[pgdg17]
...
exclude=pgpool*

[pgdg16]
...
exclude=pgpool*

[pgdg15]
...
exclude=pgpool*

[pgdg14]
...
exclude=pgpool*

[pgdg13]
...
exclude=pgpool*
```

--------------------------------

### Initialize database with pgbench

Source: https://www.pgpool.net/docs/latest/en/html/example-basic.html

Run pgbench with the -i flag to populate the database with standard test tables and data.

```bash
$ pgbench -i -p 9999 bench_replication
```

--------------------------------

### Initialize pcp.conf

Source: https://www.pgpool.net/docs/latest/en/html/example-basic.html

Copy the sample PCP configuration file to the active configuration path.

```bash
     $ cp /usr/local/etc/pcp.conf.sample /usr/local/etc/pcp.conf
```

--------------------------------

### Install Dependencies for Rocky Linux 10

Source: https://www.pgpool.net/docs/latest/en/html/install-rpm.html

Before installing Pgpool-II on Rocky Linux 10, enable the EPEL repository and install `libmemcached-awesome-devel` to satisfy dependencies.

```shell
dnf install epel-release
dnf install libmemcached-awesome-devel
```

--------------------------------

### Initialize pgbench tables

Source: https://www.pgpool.net/docs/latest/en/html/tutorial-testing-replication.html

Create the benchmark tables required for testing using the pgbench tool.

```bash
    $ pgbench -i -p 11000 test
```

--------------------------------

### Install and set permissions for failover scripts

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Copy sample scripts to the configuration directory and set the appropriate ownership.

```bash
[root@server1 ~]# cp -p /etc/pgpool-II/sample_scripts/failover.sh.sample /etc/pgpool-II/failover.sh
[root@server1 ~]# cp -p /etc/pgpool-II/sample_scripts/follow_primary.sh.sample /etc/pgpool-II/follow_primary.sh
[root@server1 ~]# chown postgres:postgres /etc/pgpool-II/{failover.sh,follow_primary.sh}
```

--------------------------------

### Initialize pgpool.conf

Source: https://www.pgpool.net/docs/latest/en/html/example-basic.html

Copy the sample configuration file to the active configuration path.

```bash
     $ cp /usr/local/etc/pgpool.conf.sample /usr/local/etc/pgpool.conf
```

--------------------------------

### Run pgpool_setup for Streaming Replication

Source: https://www.pgpool.net/docs/latest/en/html/pgpool-setup.html

Execute the pgpool_setup script to initialize PostgreSQL in streaming replication mode. This process creates database clusters, configures PostgreSQL and Pgpool-II, and sets up replication scripts.

```bash
$ pgpool_setup 
PostgreSQL major version: 124
Starting set up in streaming replication mode
creating startall and shutdownall
creating failover script
creating database cluster /tmp/test/data0...done.
update postgresql.conf
creating pgpool_remote_start
creating basebackup.sh
creating recovery.conf
creating database cluster /tmp/test/data1...done.
update postgresql.conf
creating pgpool_remote_start
creating basebackup.sh
creating recovery.conf
temporarily start data0 cluster to create extensions
temporarily start pgpool-II to create standby nodes
 node_id | hostname | port  | status | lb_weight |  role   | select_cnt | load_balance_node | replication_delay | replication_state | replication_sync_state | last_status_change  
---------+----------+-------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+------------------------+---------------------
 0       | /tmp     | 11002 | up     | 0.500000  | primary | 0          | true              | 0                 |                   |                        | 2020-08-18 13:50:19
 1       | /tmp     | 11003 | down   | 0.500000  | standby | 0          | false             | 0                 |                   |                        | 2020-08-18 13:50:18
(2 rows)

recovery node 1...pcp_recovery_node -- Command Successful
done.
creating follow primary script
 node_id | hostname | port  | status | lb_weight |  role   | select_cnt | load_balance_node | replication_delay | replication_state | replication_sync_state | last_status_change  
---------+----------+-------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+------------------------+---------------------
 0       | /tmp     | 11002 | up     | 0.500000  | primary | 0          | true              | 0                 |                   |                        | 2020-08-18 13:50:19
 1       | /tmp     | 11003 | up     | 0.500000  | standby | 0          | false             | 0                 |                   |                        | 2020-08-18 13:50:23
(2 rows)

shutdown all

pgpool-II setting for streaming replication mode is done.
To start the whole system, use /tmp/test/startall.
To shutdown the whole system, use /tmp/test/shutdownall.
pc p command user name is "t-ishii", password is "t-ishii".
Each PostgreSQL, pgpool-II and pcp port is as follows:
#1 port is 11002
#2 port is 11003
pgpool port is 11000
pc p port is 11001
The info above is in README.port.

```

--------------------------------

### Example pgproto input data file

Source: https://www.pgpool.net/docs/latest/en/html/pgproto.html

A sample data file demonstrating various PostgreSQL protocol messages like Query, Parse, Bind, Execute, and Sync.

```text
    #
    # Test data example
    #
    'Q'	"SELECT * FROM aaa"
    'Y'
    'P'	"S1"	"BEGIN"	0
    'B'	""	"S1"	0	0	0
    'E'	""	0
    'C'	'S'	"S1"
    'P'	"foo"	"SELECT 1"	0
    'B'	"myportal"	"foo"	0	0	0
    'E'	"myportal"	0
    'P'	"S2"	"COMMIT"	0
    'B'	""	"S2"	0	0	0
    'E'	""	0
    'C'	'S'	"S2"
    'S'
    'Y'
    'X'
```

--------------------------------

### Install Pgpool-II on Rocky Linux 10

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Commands to install Pgpool-II and its dependencies on Rocky Linux 10.

```bash
[all servers]# dnf install -y https://www.pgpool.net/yum/rpms/4.7/redhat/rhel-10-x86_64/pgpool-II-release-4.7-1.noarch.rpm
[all servers]# dnf install -y epel-release
[all servers]# dnf install -y libmemcached-awesome-devel
[all servers]# dnf install -y pgpool-II-pg18-*
```

--------------------------------

### Basic Pgpool.conf Configuration Example

Source: https://www.pgpool.net/docs/latest/en/html/config-setting.html

Illustrates the basic syntax for the pgpool.conf file, showing comments, parameter assignments, and quoted string values. Each parameter is on a new line, and the equal sign is optional. Whitespace is generally ignored.

```plaintext
# This is a comment
listen_addresses = 'localhost'
port = 9999
serialize_accept = off
reset_query_list = 'ABORT; DISCARD ALL'
```

--------------------------------

### Install PostgreSQL Server

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Commands to install PostgreSQL 18 from the official YUM repository on all cluster nodes.

```bash
[all servers]# dnf install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-10-x86_64/pgdg-redhat-repo-latest.noarch.rpm
[all servers]# dnf -qy module disable postgresql
[all servers]# dnf install -y postgresql18-server
```

--------------------------------

### Initialize pgbench for replication testing

Source: https://www.pgpool.net/docs/latest/en/html/example-replication-mode.html

Creates a test database and initializes pgbench tables on the Pgpool-II cluster.

```bash
[server1]# /usr/pgsql-18/bin/createdb test -U postgres -p 9999
[server1]# /usr/pgsql-18/bin/pgbench -h server1 -U postgres -i -p 9999 test
```

--------------------------------

### Install Pgpool-II Core Package

Source: https://www.pgpool.net/docs/latest/en/html/install-rpm.html

Install the main Pgpool-II package. Replace 'pg18' with your PostgreSQL version.

```shell
dnf install pgpool-II-pg18
```

--------------------------------

### Install Pgpool-II on Rocky Linux 9

Source: https://www.pgpool.net/docs/latest/en/html/example-cluster.html

Command to install Pgpool-II on Rocky Linux 9 using the crb repository.

```bash
[all servers]# dnf install -y --enablerepo=crb pgpool-II-pg18-*
```

--------------------------------

### Start Pgpool-II and PostgreSQL Services

Source: https://www.pgpool.net/docs/latest/en/html/pgpool-setup.html

Use the generated startall script to initiate all PostgreSQL and Pgpool-II services. This command ensures that both the primary and standby nodes are running.

```bash
t-ishii$ ./startall 
waiting for server to start....5744 2020-08-18 13:50:27 JST LOG:  starting PostgreSQL 12.4 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0, 64-bit
5744 2020-08-18 13:50:27 JST LOG:  listening on IPv4 address "0.0.0.0", port 11002
5744 2020-08-18 13:50:27 JST LOG:  listening on IPv6 address "::", port 11002
5744 2020-08-18 13:50:27 JST LOG:  listening on Unix socket "/tmp/.s.PGSQL.11002"
5744 2020-08-18 13:50:27 JST LOG:  redirecting log output to logging collector process
5744 2020-08-18 13:50:27 JST HINT:  Future log output will appear in directory "log".
 done
server started
waiting for server to start....5757 2020-08-18 13:50:27 JST LOG:  starting PostgreSQL 12.4 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0, 64-bit
5757 2020-08-18 13:50:27 JST LOG:  listening on IPv4 address "0.0.0.0", port 11003
5757 2020-08-18 13:50:27 JST LOG:  listening on IPv6 address "::", port 11003
5757 2020-08-18 13:50:27 JST LOG:  listening on Unix socket "/tmp/.s.PGSQL.11003"
5757 2020-08-18 13:50:27 JST LOG:  redirecting log output to logging collector process
5757 2020-08-18 13:50:27 JST HINT:  Future log output will appear in directory "log".
 done
server started

```

--------------------------------

### Install Pgpool-II Packages

Source: https://www.pgpool.net/docs/latest/en/html/example-replication-mode.html

Installs Pgpool-II packages using the Pgpool-II YUM repository. This command assumes the repository has been added.

```bash
[all servers]# yum install -y https://www.pgpool.net/yum/rpms/4.6/redhat/rhel-10-x86_64/pgpool-II-release-4.6-1.noarch.rpm
[all servers]# yum install -y pgpool-II-pg18-*
  

```

--------------------------------

### Log message examples for parameter status

Source: https://www.pgpool.net/docs/latest/en/html/release-3-7-23.html

Examples of log messages generated by pgpool-II when handling parameter status discrepancies.

```text
     LOG:  reading message length
     DETAIL:  message length (22) in slot 1 does not match with slot 0(23)
```

```text
     LOG:  ParameterStatus "TimeZone": node 1 message length 30 is different from main node message length 24
```

--------------------------------

### Compile Pgpool-II Documentation

Source: https://www.pgpool.net/docs/latest/en/html/install-docs.html

Navigate to the 'doc' directory and run 'make' to compile the English documentation. Repeat for 'doc.ja' to compile Japanese documentation.

```bash
$ cd doc
$ make
$ cd ..
$ cd doc.ja
$ make
```

--------------------------------

### EXPLAIN with GENERIC_PLAN option

Source: https://www.pgpool.net/docs/latest/en/html/release-4-5-0.html

Illustrates the use of the GENERIC_PLAN option with EXPLAIN to display the generic plan for a parameterized query.

```sql
EXPLAIN (GENERIC_PLAN) SELECT ...;
```

--------------------------------

### Install Docbook tools on RHEL

Source: https://www.pgpool.net/docs/latest/en/html/install-docs.html

Use this command to install the necessary Docbook tools on RHEL or similar systems. Ensure the 'powertools' repository is enabled.

```bash
dnf install --enablerepo=powertools docbook-dtds docbook-style-dsssl docbook-style-xsl libxslt openjade
```

--------------------------------

### Copy Sample pgpool.conf

Source: https://www.pgpool.net/docs/latest/en/html/configuring-pgpool.html

Copy the sample pgpool.conf file to use as your main configuration. This is typically done in the /usr/local/etc directory after installing from source.

```bash
# cd /usr/local/etc
# cp pgpool.conf.sample pgpool.conf
```

--------------------------------

### Install pgpool_adm Extension

Source: https://www.pgpool.net/docs/latest/en/html/pgpool-adm.html

Steps to compile and install the pgpool_adm extension on PostgreSQL servers. Ensure you are in the extension's source directory before running make commands.

```bash
      $ cd src/sql/pgpool_adm
      $ make
      $ make install
```

```sql
      $ psql ...
      $ CREATE EXTENSION pgpool_adm
```

--------------------------------

### Install Pgpool-II RPM Repository

Source: https://www.pgpool.net/docs/latest/en/html/install-rpm.html

Install the Pgpool-II official YUM repository configuration file. Replace '4.7' and 'rhel-10-x86_64' with your specific Pgpool-II and distribution versions.

```shell
dnf install https://www.pgpool.net/yum/rpms/4.7/redhat/rhel-10-x86_64/pgpool-II-release-4.7-1.noarch.rpm
```

--------------------------------

### Copy Sample pgpool.conf

Source: https://www.pgpool.net/docs/latest/en/html/tutorial-replication.html

Copy the sample pgpool.conf file to pgpool.conf to begin configuration. This is a prerequisite for setting up streaming replication.

```bash
cp /usr/local/etc/pgpool.conf.sample pgpool.conf
```

--------------------------------

### Install PostgreSQL and Server Packages

Source: https://www.pgpool.net/docs/latest/en/html/example-replication-mode.html

Installs PostgreSQL server packages from the official PostgreSQL YUM repository on all servers. Ensure the PostgreSQL YUM repository is configured correctly.

```bash
[all servers]# yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-10-x86_64/pgdg-redhat-repo-latest.noarch.rpm
[all servers]# yum install -y postgresql18-server
  

```

--------------------------------

### Install Pgpool-II Extensions for Online Recovery

Source: https://www.pgpool.net/docs/latest/en/html/install-rpm.html

Install the extensions package on all PostgreSQL servers to use the online recovery feature. This package depends on the core Pgpool-II package.

```shell
dnf install pgpool-II-pg18-extensions pgpool-II-pg18
```

--------------------------------

### Show All Configuration Parameters

Source: https://www.pgpool.net/docs/latest/en/html/sql-pgpool-show.html

Displays all configuration parameters for Pgpool-II, including their values and descriptions. This provides a comprehensive overview of the current settings.

```bash
PGPOOL SHOW ALL;
item                     |          value          |              description
-------------------------+-------------------------+-----------------------------------------------------------
backend_hostname0        | 127.0.0.1               | hostname or IP address of PostgreSQL backend.
backend_port0            | 5434                    | port number of PostgreSQL backend.
backend_weight0          | 0                       | load balance weight of backend.
backend_data_directory0  | /var/lib/pgsql/data     | data directory of the backend.
backend_flag0            | ALLOW_TO_FAILOVER       | Controls various backend behavior.
backend_hostname1        | 127.0.0.1               | hostname or IP address of PostgreSQL backend.
backend_port1            | 5432                    | port number of PostgreSQL backend.
backend_weight1          | 1                       | load balance weight of backend.
backend_data_directory1  | /home/work/installed/pg | data directory of the backend.
backend_flag1            | ALLOW_TO_FAILOVER       | Controls various backend behavior.
hostname0                | localhost               | Hostname of pgpool node for watchdog connection.
.
.
.
ssl                      | off                     | Enables SSL support for frontend and backend connections
(138 rows)
```

--------------------------------

### CLI Command: watchdog_setup

Source: https://www.pgpool.net/docs/latest/en/html/watchdog-setup.html

The watchdog_setup command creates a temporary installation of Pgpool-II clusters with watchdog enabled in the current directory.

```APIDOC
## watchdog_setup

### Description
Creates a temporary installation of Pgpool-II clusters with watchdog enabled, including specified numbers of Pgpool-II and PostgreSQL installations. This tool is intended for testing purposes only.

### Parameters
#### Options
- **-wn** (integer) - Optional - Number of Pgpool-II installations (default: 3).
- **-wp** (integer) - Optional - Starting base port number for Pgpool-II and PostgreSQL (default: 50000).
- **-m** (string) - Optional - Running mode: 'r' (native replication), 'i' (snapshot isolation), 's' (streaming replication), 'l' (logical replication), or 'n' (raw mode) (default: 's').
- **-n** (integer) - Optional - Number of PostgreSQL installations (default: 2).
- **-vip** (string) - Optional - Virtual IP address (default: '127.0.0.1').
- **--no-stop** (flag) - Optional - Do not stop pgpool and PostgreSQL after the work.
- **-d** (flag) - Optional - Start pgpool with debug mode.

### Environment Variables
- **PGPOOL_SETUP** - Path to pgpool_setup command.
- **PGPOOL_INSTALL_DIR** - Pgpool-II installation directory.
- **PGPOOLDIR** - Path to Pgpool-II configuration files.
- **PGBIN** - Path to PostgreSQL commands.
- **PGLIB** - Path to PostgreSQL shared libraries.
- **PGSOCKET_DIR** - Path to Unix socket directory.
- **INITDBARG** - Arguments for initdb command.
```
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