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Postgres

Features

Feature Supported Notes
Full Refresh Sync Yes
Incremental - Append Sync Yes
Replicating Views Yes
Replicate Incremental Deletes Yes
Logical Replication (WAL) Yes
SSL Support Yes
SSH Tunnel Connection Yes
Namespaces Yes Enabled by default.
Custom Types Yes
Arrays Yes Byte-arrays are not supported yet.
Generating an RSA Private Key No Coming Soon.
Schema Selection No Track issue here.

The Postgres source does not alter the schema present in your database. Depending on the destination connected to this source, however, the schema may be altered. See the destination's documentation for more details.

Getting Started (Airbyte Cloud)

On Airbyte Cloud, only TLS connections to your Postgres instance are supported. Other than that, you can proceed with the open-source instructions below.

Getting Started (Airbyte Open-Source)

Requirements

  1. Postgres v9.3.x or above
  2. Allow connections from Airbyte to your Postgres database (if they exist in separate VPCs)
  3. Create a dedicated read-only Airbyte user with access to all tables needed for replication

1. Make sure your database is accessible from the machine running Airbyte

This is dependent on your networking setup. The easiest way to verify if Airbyte is able to connect to your Postgres instance is via the check connection tool in the UI.

2. Create a dedicated read-only user with access to the relevant tables (Recommended but optional)

This step is optional but highly recommended to allow for better permission control and auditing. Alternatively, you can use Airbyte with an existing user in your database.

To create a dedicated database user, run the following commands against your database:

CREATE USER airbyte PASSWORD 'your_password_here';

Then give it access to the relevant schema:

GRANT USAGE ON SCHEMA <schema_name> TO airbyte

Note that to replicate data from multiple Postgres schemas, you can re-run the command above to grant access to all the relevant schemas, but you'll need to set up multiple sources connecting to the same db on multiple schemas.

Next, grant the user read-only access to the relevant tables. The simplest way is to grant read access to all tables in the schema as follows:

GRANT SELECT ON ALL TABLES IN SCHEMA <schema_name> TO airbyte;

# Allow airbyte user to see tables created in the future
ALTER DEFAULT PRIVILEGES IN SCHEMA <schema_name> GRANT SELECT ON TABLES TO airbyte;

3. Optionally, set up CDC. Follow the guide below to do so.

4. That's it!

Your database user should now be ready for use with Airbyte.

Change Data Capture (CDC) / Logical Replication / WAL Replication

We use logical replication of the Postgres write-ahead log (WAL) to incrementally capture deletes using a replication plugin.

We use pgoutput as a default plugin, which is included in Postgres 10+. Also wal2json plugin is supported, please read the section on replication plugins below for more information.

Please read the CDC docs for an overview of how Airbyte approaches CDC.

Should I use CDC for Postgres?

  • If you need a record of deletions and can accept the limitations posted below, you should to use CDC for Postgres.
  • If your data set is small and you just want snapshot of your table in the destination, consider using Full Refresh replication for your table instead of CDC.
  • If the limitations prevent you from using CDC and your goal is to maintain a snapshot of your table in the destination, consider using non-CDC incremental and occasionally reset the data and re-sync.
  • If your table has a primary key but doesn't have a reasonable cursor field for incremental syncing (i.e. updated_at), CDC allows you to sync your table incrementally.

CDC Limitations

  • Make sure to read our CDC docs to see limitations that impact all databases using CDC replication.
  • CDC is only available for Postgres 10+.
  • Airbyte requires a replication slot configured only for its use. Only one source should be configured that uses this replication slot. Instructions on how to set up a replication slot can be found below.
  • Log-based replication only works for master instances of Postgres.
  • Using logical replication increases disk space used on the database server. The additional data is stored until it is consumed.
    • We recommend setting frequent syncs for CDC in order to ensure that this data doesn't fill up your disk space.
    • If you stop syncing a CDC-configured Postgres instance to Airbyte, you should delete the replication slot. Otherwise, it may fill up your disk space.
  • Our CDC implementation uses at least once delivery for all change records.

Setting up CDC for Postgres

1. Enable logical replication

Follow one of these guides to enable logical replication:

2. Add user-level permissions

We recommend using a user specifically for Airbyte's replication so you can minimize access. This Airbyte user for your instance needs to be granted REPLICATION and LOGIN permissions. You can create a role with CREATE ROLE <name> REPLICATION LOGIN; and grant that role to the user. You still need to make sure the user can connect to the database, use the schema, and to use SELECT on tables (the same are required for non-CDC incremental syncs and all full refreshes).

3. Select replication plugin

We recommend using a pgoutput plugin as it is the standard logical decoding plugin in Postgres. In case the replication table contains a lot of big JSON blobs and table size exceeds 1 GB, we recommend using a wal2json instead. Please note that wal2json may require additional installation for Bare Metal, VMs (EC2/GCE/etc), Docker, etc. For more information read wal2json documentation.

4. Create replication slot

Next, you will need to create a replication slot. Here is the query used to create a replication slot called airbyte_slot:

SELECT pg_create_logical_replication_slot('airbyte_slot', 'pgoutput');

If you would like to use wal2json plugin, please change pgoutput to wal2json value in the above query.

5. Create publications and replication identities for tables

For each table you want to replicate with CDC, you should add the replication identity (the method of distinguishing between rows) first. We recommend using ALTER TABLE tbl1 REPLICA IDENTITY DEFAULT; to use primary keys to distinguish between rows. After setting the replication identity, you will need to run CREATE PUBLICATION airbyte_publication FOR TABLE <tbl1, tbl2, tbl3>;. This publication name is customizable. You must add the replication identity before creating the publication. Otherwise, ALTER/UPDATE/DELETE statements may fail if Postgres cannot determine how to uniquely identify rows. Please refer to the Postgres docs if you need to add or remove tables from your publication in the future.

The UI currently allows selecting any tables for CDC. If a table is selected that is not part of the publication, it will not replicate even though it is selected. If a table is part of the publication but does not have a replication identity, that replication identity will be created automatically on the first run if the Airbyte user has the necessary permissions.

6. Start syncing

When configuring the source, select CDC and provide the replication slot and publication you just created. You should be ready to sync data with CDC!

CDC on Bare Metal, VMs (EC2/GCE/etc), Docker, etc.

Some settings must be configured in the postgresql.conf file for your database. You can find the location of this file using psql -U postgres -c 'SHOW config_file' withe the correct psql credentials specified. Alternatively, a custom file can be specified when running postgres with the -c flag. For example postgres -c config_file=/etc/postgresql/postgresql.conf runs Postgres with the config file at /etc/postgresql/postgresql.conf.

If you are syncing data from a server using the postgres Docker image, you will need to mount a file and change the command to run Postgres with the set config file. If you're just testing CDC behavior, you may want to use a modified version of a sample postgresql.conf.

  • wal_level is the type of coding used within the Postgres write-ahead log. This must be set to logical for Airbyte CDC.
  • max_wal_senders is the maximum number of processes used for handling WAL changes. This must be at least one.
  • max_replication_slots is the maximum number of replication slots that are allowed to stream WAL changes. This must one if Airbyte will be the only service reading subscribing to WAL changes or more if other services are also reading from the WAL.

Here is what these settings would look like in postgresql.conf:

wal_level = logical             
max_wal_senders = 1             
max_replication_slots = 1

After setting these values you will need to restart your instance.

Finally, follow the rest of steps above.

CDC on AWS Postgres RDS or Aurora

  • Go to the Configuration tab for your DB cluster.
  • Find your cluster parameter group. You will either edit the parameters for this group or create a copy of this parameter group to edit. If you create a copy you will need to change your cluster's parameter group before restarting.
  • Within the parameter group page, search for rds.logical_replication. Select this row and click on the Edit parameters button. Set this value to 1.
  • Wait for a maintenance window to automatically restart the instance or restart it manually.
  • Finally, follow the rest of steps above.

CDC on Azure Database for Postgres

Use either the Azure CLI to:

az postgres server configuration set --resource-group group --server-name server --name azure.replication_support --value logical
az postgres server restart --resource-group group --name server

Finally, follow the rest of steps above.

Connection via SSH Tunnel

Airbyte has the ability to connect to a Postgres instance via an SSH Tunnel. The reason you might want to do this because it is not possible (or against security policy) to connect to the database directly (e.g. it does not have a public IP address).

When using an SSH tunnel, you are configuring Airbyte to connect to an intermediate server (a.k.a. a bastion sever) that does have direct access to the database. Airbyte connects to the bastion and then asks the bastion to connect directly to the server.

Using this feature requires additional configuration, when creating the source. We will talk through what each piece of configuration means.

  1. Configure all fields for the source as you normally would, except SSH Tunnel Method.
  2. SSH Tunnel Method defaults to No Tunnel (meaning a direct connection). If you want to use an SSH Tunnel choose SSH Key Authentication or Password Authentication.
    1. Choose Key Authentication if you will be using an RSA Private as your secrets for establishing the SSH Tunnel (see below for more information on generating this key).
    2. Choose Password Authentication if you will be using a password as your secret for establishing the SSH Tunnel.
  3. SSH Tunnel Jump Server Host refers to the intermediate (bastion) server that Airbyte will connect to. This should be a hostname or an IP Address.
  4. SSH Connection Port is the port on the bastion server with which to make the SSH connection. The default port for SSH connections is 22, so unless you have explicitly changed something, go with the default.
  5. SSH Login Username is the username that Airbyte should use when connection to the bastion server. This is NOT the Postgres username.
  6. If you are using Password Authentication, then SSH Login Username should be set to the password of the User from the previous step. If you are using SSH Key Authentication leave this blank. Again, this is not the Postgres password, but the password for the OS-user that Airbyte is using to perform commands on the bastion.
  7. If you are using SSH Key Authentication, then SSH Private Key should be set to the RSA Private Key that you are using to create the SSH connection. This should be the full contents of the key file starting with -----BEGIN RSA PRIVATE KEY----- and ending with -----END RSA PRIVATE KEY-----.

Generating an RSA Private Key

The connector expects an RSA key in PEM format. To generate this key:

ssh-keygen -t rsa -m PEM -f myuser_rsa

This produces the private key in pem format, and the public key remains in the standard format used by the authorized_keys file on your bastion host. The public key should be added to your bastion host to whichever user you want to use with Airbyte. The private key is provided via copy-and-paste to the Airbyte connector configuration screen, so it may log in to the bastion.

Data type mapping

Postgres data types are mapped to the following data types when synchronizing data. You can check the test values examples here. If you can't find the data type you are looking for or have any problems feel free to add a new test!

Postgres Type Resulting Type Notes
bigint number
bigserial number
bit boolean
blob boolean
boolean boolean
box string
bytea object
character string
character varying string
cidr string
circle string
citext string
date string
double precision string
enum number
float number
float8 number
hstore object may be de-nested depending on the destination you are syncing into
inet string
int number
interval string
inventory_item string
json string
jsonb string
line string
lseg string
macaddr string
macaddr8 string
money string When running logical replication (CDC), money values larger than 999999999999999 (15 nines) or smaller than -999999999999999 (15 nines) are transmitted as null;
mood string
numeric number
path string
point number
polygon number
real number
serial number
smallint number
smallserial number
text string
text[] string
time string
timez string
time with timezone string may be written as a native date type depending on the destination
time without timezone string may be written as a native date type depending on the destination
timestamp with timezone string may be written as a native date type depending on the destination
timestamp without timezone string may be written as a native date type depending on the destination
tsrange string
tsvector string
uuid string
varchar string
xml string

Changelog

Version Date Pull Request Subject
0.3.14 2021-11-17 8010 Added checking of privileges before table internal discovery
0.3.13 2021-10-26 7339 Support or improve support for Interval, Money, Date, various geometric data types, inventory_items, and others
0.3.12 2021-09-30 6585 Improved SSH Tunnel key generation steps
0.3.11 2021-09-02 5742 Add SSH Tunnel support
0.3.9 2021-08-17 5304 Fix CDC OOM issue
0.3.8 2021-08-13 4699 Added json config validator
0.3.4 2021-06-09 3973 Add AIRBYTE_ENTRYPOINT for Kubernetes support
0.3.3 2021-06-08 3960 Add method field in specification parameters
0.3.2 2021-05-26 3179 Remove isCDC logging
0.3.1 2021-04-21 2878 Set defined cursor for CDC
0.3.0 2021-04-21 2990 Support namespaces
0.2.7 2021-04-16 2923 SSL spec as optional
0.2.6 2021-04-16 2757 Support SSL connection
0.2.5 2021-04-12 2859 CDC bugfix
0.2.4 2021-04-09 2548 Support CDC
0.2.3 2021-03-28 2600 Add NCHAR and NVCHAR support to DB and cursor type casting
0.2.2 2021-03-26 2460 Destination supports destination sync mode
0.2.1 2021-03-18 2488 Sources support primary keys
0.2.0 2021-03-09 2238 Protocol allows future/unknown properties
0.1.13 2021-02-02 1887 Migrate AbstractJdbcSource to use iterators
0.1.12 2021-01-25 1746 Fix NPE in State Decorator
0.1.11 2021-01-25 1765 Add field titles to specification
0.1.10 2021-01-19 1724 Fix JdbcSource handling of tables with same names in different schemas
0.1.9 2021-01-14 1655 Fix JdbcSource OOM
0.1.8 2021-01-13 1588 Handle invalid numeric values in JDBC source
0.1.7 2021-01-08 1307 Migrate Postgres and MySql to use new JdbcSource
0.1.6 2020-12-09 1172 Support incremental sync
0.1.5 2020-11-30 1038 Change JDBC sources to discover more than standard schemas
0.1.4 2020-11-30 1046 Add connectors using an index YAML file