Creating PostgreSQL clusters
A PostgreSQL cluster is one or more database hosts that replication can be configured between. Replication is enabled by default in any cluster consisting of more than one host: the master host accepts write requests, synchronously duplicates changes in the primary replica, and does it asynchronously in all the others.
The number of hosts that can be created together with a PostgreSQL cluster depends on the storage option selected:
When using network drives, you can request any number of hosts (from one to the limits of the current quota).
When using SSDs, you can create at least three replicas along with the cluster (a minimum of three replicas is required to ensure fault tolerance). If the available folder resources are still sufficient after creating a cluster, you can add extra replicas.
By default, Managed Service for PostgreSQL limits the maximum number of connections to each PostgreSQL cluster host. This maximum is calculated as follows:
200 × <number of vCPUs per host>. For example, for a cluster of the s1.micro class the
max_connections default parameter value is 400 and it cannot be increased.
The total number of connections reserved for users must not exceed the value of the parameter
max_connections. Keep in mind that Managed Service for PostgreSQL reserves 15 connections for service users per user PostgreSQL host. For example, if the cluster has the setting
"max_connections": 100 you can reserve a maximum of 85 connections for cluster users.
How to create a PostgreSQL cluster
In the management console, select the folder where you want to create a DB cluster.
Select Managed Service for PostgreSQL.
Click Create cluster.
Enter the cluster name in the Cluster name field. The cluster name must be unique within the Cloud.
Select the environment where you want to create the cluster (you cannot change the environment after cluster creation):
production— for stable versions of your apps.
prestable— for testing, including the Managed Service for PostgreSQL service itself. The prestable environment is updated more often, which means that known problems are fixed sooner in it, but this may cause backward incompatible changes.
Select the DBMS version.
Select the host class that will define the technical specifications of the VMs where the DB hosts will be deployed. All available options are listed in Host classes. When you change the host class for the cluster, the characteristics of all existing hosts change, too.
In the Storage size section:
- Выберите тип хранилища — более гибкое сетевое (network-hdd или network-ssd) или более быстрое локальное SSD-хранилище (local-ssd). Размер локального хранилища можно менять только с шагом 100 ГБ.
- Select the size to be used for data and backups. For more information about how backups take up storage space, see Backups.
In the Database section, specify DB attributes:
- Database name. The DB name must be unique within the folder and contain only Latin letters, numbers, and underscores.
- The name of the user who is the DB owner. The username may only contain Latin letters, numbers, and underscores. By default, the new user is assigned 50 connections to each host in the cluster.
- User's password (from 8 to 128 characters).
Under Hosts, select parameters for the database hosts created with the cluster (keep in mind that if you use SSDs when creating a PostgreSQL cluster, you can set at least three hosts). If you open the Advanced settings section, you can choose specific subnets for each host. By default, each host is created in a separate subnet.
Click Create cluster.
If you don't have the Yandex.Cloud command line interface yet, install it.
The folder specified in the CLI profile is used by default. You can specify a different folder using the
To create a cluster:
Check whether the folder has any subnets for the cluster hosts:
$ yc vpc subnet list
If there are no subnets in the folder, create the necessary subnets in VPC.
See the description of the CLI's create cluster command:
$ yc managed-postgresql cluster create --help
Specify the cluster parameters in the create command (only some of the supported parameters are given in the example):
$ yc managed-postgresql cluster create \ --name <cluster name> \ --environment <prestable or production> \ --network-name <network name> \ --host zone-id=<availability zone>,subnet-id=<subnet ID> \ --resource-preset <host class> \ --user name=<username>,password=<user password> \ --database name=<database name>,owner=<database owner name> \ --disk-size <storage size in GB>
The subnet ID
subnet-idshould be specified if the selected availability zone contains two or more subnets.
Creating a single-host cluster
To create a cluster with a single host, you should pass a single parameter,
Let's say we need to create a PostgreSQL cluster with the following characteristics:
- In the
- In the
- With a single host of the
s1.nanoclass in the
b0rcctk2rvtr8efcch64subnet and the
- With SSD network storage of 20 GB.
- With one user (
user1) and the password
- With one
db1database owned by the user
Run the command:
$ yc managed-postgresql cluster create \ --name mypg \ --environment production \ --network-name default \ --resource-preset s1.nano \ --host zone-id=ru-central1-c,subnet-id=b0rcctk2rvtr8efcch64 \ --disk-type network-ssd \ --disk-size 20 \ --user name=user1,password=user1user1 \ --database name=db1,owner=user1