Read replicas¶
Table of contents
Introduction¶
Hasura Cloud can load balance queries and subscriptions across read replicas while sending all mutations and metadata API calls to the primary.
Adding read replica urls¶
Postgres¶
Head to Data -> Manage -> <db-name> -> Edit
You can add read replicas for a database by adding their config to the /metadata/databases/database.yaml file:
- name: <db-name>
kind: postgres
configuration:
connection_info:
database_url:
from_env: <DATABASE_URL_ENV>
pool_settings:
idle_timeout: 180
max_connections: 50
retries: 1
read_replicas:
- database_url:
from_env: <DATABASE_REPLICA_URL_ENV>
pool_settings:
idle_timeout: 180
max_connections: 50
retries: 1
Apply the metadata by running:
hasura metadata apply
You can add read replicas for a database using the pg_add_source metadata API
POST /v1/metadata HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin
{
"type": "pg_add_source",
"args": {
"name": "<db_name>",
"replace_configuration": true,
"configuration": {
"connection_info": {
"database_url": {
"from_env": "<DATABASE_URL_ENV>"
}
},
"read_replicas": [
{
"database_url": {
"from_env": "<DATABASE_REPLICA_URL_ENV>"
},
"pool_settings": {
"retries": 1,
"idle_timeout": 180,
"max_connections": 50
}
}
]
}
}
For existing v1.3 projects
If you have configured your Postgres instances with replicas, the replica URLs can be added to Hasura using the following environment variable in your project ENV Vars tab:
HASURA_GRAPHQL_READ_REPLICA_URLS=postgres://user:password@replica-host:5432/db
If you have multiple replicas, their urls can be added as comma separated values.
Additional environment variables for read replicas specifically:
HASURA_GRAPHQL_CONNECTIONS_PER_READ_REPLICA
HASURA_GRAPHQL_STRIPES_PER_READ_REPLICA
MS SQL Server¶
You can add read replicas for a database by adding their config to the /metadata/databases/database.yaml file:
- name: <db-name>
kind: mssql
configuration:
connection_info:
connection_string: <DATABASE_URL>
pool_settings:
idle_timeout: 180
max_connections: 50
read_replicas:
- connection_string: <DATABASE_REPLICA_URL>
pool_settings:
idle_timeout: 25,
max_connections: 100
Apply the metadata by running:
hasura metadata apply
You can add read replicas for a database using the using the mssql_add_source metadata API
POST /v1/metadata HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin
{
"type":"mssql_add_source",
"args":{
"name":"<db_name>",
"replace_configuration": true,
"configuration":{
"connection_info":{
"connection_string":{
"from_env":"<DATABASE_URL>"
},
"pool_settings":{
"max_connections":50,
"idle_timeout":180
},
"read_replicas":[
{
"connection_string":"<DATABASE_REPLICA_URL>",
"pool_settings":{
"idle_timeout":180,
"max_connections":50
}
}
]
}
}
}
}
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