Configure the postgresql.conf file - ApsaraDB RDS - Alibaba Cloud Documentation Center

ApsaraDB RDS for PostgreSQL allows you to use the cloud migration feature to migrate the data of the self-managed PostgreSQL instance that is deployed on an Elastic Compute Service (ECS) instance or in a data center to an ApsaraDB RDS for PostgreSQL instance. This topic describes how to configure the postgresql.conf file of a self-managed PostgreSQL instance.

Procedure

Note

In this topic, the self-managed PostgreSQL instance and the RDS instance run PostgreSQL 13 in CentOS 7.

Connect to the self-managed PostgreSQL instance and query the value of the listen_addresses parameter and the value of the wal_keep_segments or wal_keep_size parameter.

Parameter	Description	Command	Expected Value
listen_addresses	Specifies whether the self-managed PostgreSQL instance supports remote connections.	`SHOW listen_addresses;`	`*`
wal_keep_segments	Specifies the minimum number of log files that can be retained in the pg_wal directory. We recommend that you set this parameter to a value that is greater than or equal to 4096. If the value of this parameter is less than 4096, write-ahead logging (WAL) records of the self-managed PostgreSQL instance are deleted after a full backup. In this case, you must back up the self-managed PostgreSQL instance again. Note This parameter is suitable for the self-managed PostgreSQL instance that runs PostgreSQL 10, PostgreSQL 11, or PostgreSQL 12.	`SHOW wal_keep_segments;`	`4096`
wal_keep_size	Specifies the minimum size of log files that can be retained in the pg_wal directory. We recommend that you set this parameter to a value that is greater than or equal to 65536 MB. If the value of this parameter is less than 65536 MB, WAL records of the self-managed PostgreSQL instance are deleted after a full backup. In this case, you must back up the self-managed PostgreSQL instance again. Note This parameter is suitable for the self-managed PostgreSQL instance that runs PostgreSQL 13 and later versions.	`SHOW wal_keep_size;`	`65536`

If the values of the parameters meet your business requirements, you do not need to configure the postgresql.conf file. In this case, create an account that is used for the cloud migration. For more information, see Create an account for cloud migration on a self-managed PostgreSQL instance.
If the values of the parameters do not meet your business requirements, go to Step 2.

Stop the PostgreSQL database service.
Note
Only the postgres user has the permissions to run the following command. You can run the su - postgres command to switch to the postgres user.
```
/usr/pgsql-13/bin/pg_ctl stop -m fast
```
Find the postgresql.conf file.
Note
Only the root user has the permissions to run the following command. You can run the su - root command to switch to the root user.
```
find / -name postgresql.conf
```
Sample output:
```
/var/lib/pgsql/13/data/postgresql.conf
```
Go to the directory in which the postgresql.conf file is stored.
```
cd /var/lib/pgsql/13/data/
```
Run the vim postgresql.conf command to open the postgresql.conf file. Then, modify the value of the listen_addresses parameter and the value of the wal_keep_segments or wal_keep_size parameter in the file.
```
listen_addresses = '*'

# If the self-managed PostgreSQL instance runs PostgreSQL 10, PostgreSQL 11, or PostgreSQL 12, perform the following modification:
wal_keep_segments = 4096

# If the self-managed PostgreSQL instance runs PostgreSQL 13 or later versions, perform the following modification:
wal_keep_size = 65536
```
Note
The preceding parameters may be commented out by default. After you modify the value of a parameter, you must delete the number sign (#) at the beginning of the line in which the parameter resides.
Press Ecs and enter :wq to save the postgresql.conf file and exit.
Start the PostgreSQL database service.
Note
Only the postgres user has the permissions to run the following command. You can run the su - postgres command to switch to the postgres user.
```
/usr/pgsql-13/bin/pg_ctl start
```

What to do next

Create an account for cloud migration on a self-managed PostgreSQL instance