Postgres requirements¶

Table of contents

Supported Postgres versions
- Feature requirements
Postgres permissions
- Notes for managed databases (AWS RDS, GCP Cloud SQL, etc.)
pgcrypto in PG search path

Supported Postgres versions¶

Hasura GraphQL engine supports Postgres versions 9.5 and above.

Feature requirements¶

Hasura actions are supported in Postgres 10 and above.

Postgres permissions¶

If you’re running in a controlled environment, you might need to configure the Hasura GraphQL engine to use a specific Postgres user that your DBA gives you.

The Hasura GraphQL engine needs access to your Postgres database with the following permissions:

(required) Read & write access on 2 schemas: hdb_catalog and hdb_views.
(required) Read access to the information_schema and pg_catalog schemas, to query for list of tables. Note that these permissions are usually available by default to all postgres users via PUBLIC grant.
(required) Read access to the schemas (public or otherwise) if you only want to support queries.
(optional) Write access to the schemas if you want to support mutations as well.
(optional) To create tables and views via the Hasura console (the admin UI) you’ll need the privilege to create tables/views. This might not be required when you’re working with an existing database.

Here’s a sample SQL block that you can run on your database (as a superuser) to create the right credentials for a sample Hasura user:

-- We will create a separate user and grant permissions on hasura-specific
-- schemas and information_schema and pg_catalog
-- These permissions/grants are required for Hasura to work properly.

-- create a separate user for hasura
CREATE USER hasurauser WITH PASSWORD 'hasurauser';

-- create pgcrypto extension, required for UUID
CREATE EXTENSION IF NOT EXISTS pgcrypto;

-- create the schemas required by the hasura system
-- NOTE: If you are starting from scratch: drop the below schemas first, if they exist.
CREATE SCHEMA IF NOT EXISTS hdb_catalog;
CREATE SCHEMA IF NOT EXISTS hdb_views;

-- make the user an owner of system schemas
ALTER SCHEMA hdb_catalog OWNER TO hasurauser;
ALTER SCHEMA hdb_views OWNER TO hasurauser;

-- grant select permissions on information_schema and pg_catalog. This is
-- required for hasura to query the list of available tables.
-- NOTE: these permissions are usually available by default to all users via PUBLIC grant
GRANT SELECT ON ALL TABLES IN SCHEMA information_schema TO hasurauser;
GRANT SELECT ON ALL TABLES IN SCHEMA pg_catalog TO hasurauser;

-- The below permissions are optional. This is dependent on what access to your
-- tables/schemas you want give to hasura. If you want expose the public
-- schema for GraphQL query then give permissions on public schema to the
-- hasura user.
-- Be careful to use these in your production db. Consult the postgres manual or
-- your DBA and give appropriate permissions.

-- grant all privileges on all tables in the public schema. This can be customised:
-- For example, if you only want to use GraphQL regular queries and not mutations,
-- then you can set: GRANT SELECT ON ALL TABLES...
GRANT USAGE ON SCHEMA public TO hasurauser;
GRANT ALL ON ALL TABLES IN SCHEMA public TO hasurauser;
GRANT ALL ON ALL SEQUENCES IN SCHEMA public TO hasurauser;
GRANT ALL ON ALL FUNCTIONS IN SCHEMA public TO hasurauser;

-- Similarly add these for other schemas as well, if you have any.
-- GRANT USAGE ON SCHEMA <schema-name> TO hasurauser;
-- GRANT ALL ON ALL TABLES IN SCHEMA <schema-name> TO hasurauser;
-- GRANT ALL ON ALL SEQUENCES IN SCHEMA <schema-name> TO hasurauser;
-- GRANT ALL ON ALL FUNCTIONS IN SCHEMA <schema-name> TO hasurauser;

Notes for managed databases (AWS RDS, GCP Cloud SQL, etc.)¶

Hasura works out of the box with the default superuser, usually called “postgres”, created by most managed cloud database providers.

On some cloud providers, like Google Cloud SQL, if you are creating a new user and giving the above privileges, then you may notice that the following commands may throw warnings/errors:

postgres=> ALTER SCHEMA hdb_catalog OWNER TO hasurauser;
ERROR:  must be member of role "hasurauser"

This happens because the superuser created by the cloud provider sometimes has different permissions. To fix this, you can run the following command first:

-- assuming "postgres" is the superuser that you are running the commands with.
postgres=> GRANT hasurauser to postgres;
GRANT
postgres=> ALTER SCHEMA hdb_catalog OWNER TO hasurauser;

You may also notice the following commands throw warnings/errors:

postgres=> GRANT SELECT ON ALL TABLES IN SCHEMA information_schema TO hasurauser;
WARNING:  no privileges were granted for "sql_packages"
WARNING:  no privileges were granted for "sql_features"
WARNING:  no privileges were granted for "sql_implementation_info"
ERROR:  permission denied for table sql_parts

postgres=> GRANT SELECT ON ALL TABLES IN SCHEMA pg_catalog TO hasurauser;
ERROR:  permission denied for table pg_statistic

You can ignore these warnings/errors or skip granting these permission as usually all users have relevant access to information_schema and pg_catalog schemas by default (see keyword PUBLIC).

pgcrypto in PG search path¶

Hasura GraphQL engine needs the pgcrypto Postgres extension to function.

During initialization, Hasura GraphQL engine tries to install the pgcrypto extension in the public schema, if it is not already installed.

It needs to be ensured that pgcrypto is installed in a schema which is in the Postgres search path for the Postgres user/role that Hasura connects with.

If pgcrypto is installed in a schema that is not in the search path, the schema can be added to the search path by executing one of the following SQL commands depending on your setup:

-- set search path to include schemas for the entire database
ALTER DATABASE <database_name> SET search_path TO schema1,schema2;

-- OR --

-- set search path to include schemas for a particular role
ALTER ROLE <hasura_role> SET search_path TO schema1,schema2;

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