Firebase

Firebase is an app development platform built around non-relational technologies. The Firebase Wrapper supports connecting to below objects.

1. Authentication Users (read only)
2. Firestore Database Documents (read only)

Warning

Restoring a logical backup of a database with a materialized view using a foreign table can fail. For this reason, either do not use foreign tables in materialized views or use them in databases with physical backups enabled.

Preparation

Before you get started, make sure the wrappers extension is installed on your database:

create extension if not exists wrappers with schema extensions;

and then create the foreign data wrapper:

create foreign data wrapper firebase_wrapper
  handler firebase_fdw_handler
  validator firebase_fdw_validator;

Secure your credentials (optional)

By default, Postgres stores FDW credentials inide pg_catalog.pg_foreign_server in plain text. Anyone with access to this table will be able to view these credentials. Wrappers is designed to work with Vault, which provides an additional level of security for storing credentials. We recommend using Vault to store your credentials.

-- Save your Firebase credentials in Vault and retrieve the `key_id`
insert into vault.secrets (name, secret)
values (
  'firebase',
  '{
      "type": "service_account",
      "project_id": "your_gcp_project_id",
      ...
  }'
)
returning key_id;

Connecting to Firebase

We need to provide Postgres with the credentials to connect to Firebase, and any additional options. We can do this using the create server command:

With VaultWithout Vault

create server firebase_server
  foreign data wrapper firebase_wrapper
  options (
    sa_key_id '<key_ID>', -- The Key ID from above.
    project_id '<firebase_project_id>'
);

create server firebase_server
  foreign data wrapper firebase_wrapper
   options (
     sa_key '
     {
        "type": "service_account",
        "project_id": "your_gcp_project_id",
        ...
     }
    ',
     project_id 'firebase_project_id'
   );

Creating Foreign Tables

The Firebase Wrapper supports reading data from below Firebase's objects:

Firebase	Select	Insert	Update	Delete	Truncate
Authentication Users	✅	❌	❌	❌	❌
Firestore Database Documents	✅	❌	❌	❌	❌

For example:

create foreign table firebase_users (
  uid text,
  email text,
  created_at timestamp,
  attrs jsonb
)
  server firebase_server
  options (
    object 'auth/users'
  );

Note there is a meta column attrs in the foreign table, which contains all the returned data from Firebase as json format.

Foreign table options

The full list of foreign table options are below:

• object - Object name in Firebase, required.

For Authenciation users, the object name is fixed to auth/users. For Firestore documents, its format is firestore/<collection_id>, note that collection id must be a full path id. For example,

• firestore/my-collection
• firestore/my-collection/my-document/another-collection

Query Pushdown Support

This FDW doesn't support query pushdown.

Examples

Some examples on how to use Firebase foreign tables.

firestore

To map a Firestore collection provide its location using the format firestore/<collection_id> as the object option as shown below.

create foreign table firebase_docs (
  name text,
  created_at timestamp,
  updated_at timestamp,
  attrs jsonb
)
  server firebase_server
  options (
    object 'firestore/user-profiles'
  );

Note that name, created_at, and updated_at, are automatic metadata fields on all Firestore collections.

auth/users

The auth/users collection is a special case with unique metadata. The following shows how to map Firebase users to PostgreSQL table.

create foreign table firebase_users (
  uid text,
  email text,
  created_at timestamp,
  attrs jsonb
)
  server firebase_server
  options (
    object 'auth/users'
  );