PostgreSQL feature snapshot

A high-level look at Stitch's PostgreSQL (v1) integration, including release status, useful links, and the features supported in Stitch.

STITCH
Release status

Released on July 31, 2018

Supported by

Stitch

Stitch plan

Standard

Supported versions

9.3+; 9.4+ for binlog

API availability

Available

Singer GitHub repository

singer-io/tap-postgres

CONNECTION METHODS
SSH connections

Supported

SSL connections

Supported

REPLICATION SETTINGS
Anchor Scheduling

Supported

Advanced Scheduling

Supported

Table-level reset

Supported

Configurable Replication Methods

Supported

REPLICATION METHODS
Log-based Replication

Supported

Key-based Replication

Supported

Full Table Replication

Supported

DATA SELECTION
Table selection

Supported

Column selection

Supported

View replication

Supported

Select all

Supported, with prerequisites

TRANSPARENCY
Extraction Logs

Supported

Loading Reports

Supported

Connecting PostgreSQL

PostgreSQL setup requirements

To set up PostgreSQL in Stitch, you need:

  • The CREATEROLE or SUPERUSER privilege. Either permission is required to create a database user for Stitch.

  • If using Log-based Replication, you’ll need:

    • A database running PostgreSQL 9.4 or greater Earlier versions of PostgreSQL do not include logical replication functionality, which is required for Log-based Replication.
    • The SUPERUSER privilege. If using logical replication, this is required to define the appropriate server settings.
    • To connect to the master instance. Log-based replication will only work on master instances due to a feature gap in PostgreSQL 10. Based on their forums, PostgreSQL is working on adding support for using logical replication on a read replica to a future version.
    • To check for TOASTed tables and columns. TOASTed tables and columns in your PostgreSQL database can cause the following issues when using Log-Based Replication:

      1. Recurring no known snapshot errors, or
      2. Inaccurate data replication.

      Refer to the PostgreSQL documentation for more information on what TOAST is and how to identify TOASTed tables and columns in your database.

  • If you’re not using Log-based Replication, you’ll need:

    • A database running PostgreSQL 9.3.x or greater. PostgreSQL 9.3.x is the minimum version Stitch supports for PostgreSQL integrations.
    • To verify if the database is a read replica, or follower. While we always recommend connecting a replica over a production database, this also means you may need to verify some of its settings - specifically the max_standby_streaming_delay and max_standby_archive_delay settings - before connecting it to Stitch. We recommend setting these parameters to 8-12 hours for an initial replication job, and then decreasing them afterwards.

Step 1: Configure database connection settings

In this step, you’ll configure the database server to allow traffic from Stitch to access it. There are two ways to connect your database:

  • A direct connection will work if your database is publicly accessible.
  • An SSH tunnel is required if your database isn’t publicly accessible. This method uses a publicly accessible instance, or an SSH server, to act as an intermediary between Stitch and your database. The SSH server will forward traffic from Stitch through an encrypted tunnel to the private database.

Click the option you’re using below and follow the instructions.

For the connection to be successful, you’ll need to configure your firewall to allow access from our IP addresses. Whitelist the following IPs before continuing onto the next step:

  • 52.23.137.21/32

  • 52.204.223.208/32

  • 52.204.228.32/32

  • 52.204.230.227/32

  1. Follow the steps in the Setting up an SSH Tunnel for a database connection guide to set up an SSH tunnel for PostgreSQL.
  2. Complete the steps in this guide after the SSH setup is complete.

Step 2: Create a Stitch database user

Next, you’ll create a dedicated database user for Stitch. This will ensure Stitch is visible in any logs or audits, and allow you to maintain your privilege hierarchy.

Your organization may require a different process, but the simplest way to create this user is to execute the following query when logged into the PostgreSQL database as a user with the right to grant privileges.

Note: The user performing this step should also own the schema(s) that Stitch is being granted access to.

  1. Log into your database.
  2. Create the database user, replacing <stitch_username> with the name of the database user and <password> with a password:

    CREATE USER <stitch_username> WITH ENCRYPTED PASSWORD '<password>'
    
  3. Grant the database user CONNECT privileges to the database, replacing <database_name> with the name of a database you want to connect Stitch to:

    GRANT CONNECT ON DATABASE <database_name> TO <stitch_username>
    
  4. Grant the database user schema usage privileges, replacing <schema_name> with the name of a schema you want to replicate data from:

    GRANT USAGE ON SCHEMA <schema_name> TO <stitch_username>
    
  5. Grant the database user SELECT privileges by running this command for every table you want to replicate:

    GRANT SELECT ON <schema_name>.<table_name> TO <stitch_username>
    

    Limiting access to only the tables you want to replicate ensures that the integration can complete discovery (a structure sync) in a timely manner. If you encounter issues in Stitch where tables aren’t displaying, try limiting the Stitch database user’s table access.

  6. Alter the schema’s default privileges to grant SELECT privileges on tables to the database user. This is required to ensure that objects created in the schema after connecting to Stitch will remain accessible to the stitch user:

    ALTER DEFAULT PRIVILEGES IN SCHEMA <schema_name> GRANT SELECT ON TABLES TO <stitch_username>
    
  7. If you want to replicate data from multiple databases or schemas, repeat steps 3 - 6 as needed.

See the Privileges list tab for an explanation of why these permissions are required by Stitch.

In the table below are the database user privileges Stitch requires to connect to and replicate data from a PostgreSQL database.

Privilege name Reason for requirement
CONNECT

Required to connect successfully to the specified database.

USAGE

Required to access the objects contained in the specified schema.

SELECT

Required to select rows from tables in the specified schema.

ALTER DEFAULT PRIVILEGES

Required to ensure that objects created in the schema after connecting to Stitch will be accessible by the Stitch database user.

Step 3: Configure Log-based Incremental Replication

While Log-based Incremental Replication is the most accurate and efficient method of replication, using this replication method may, at times, require manual intervention or impact the source database’s performance. Refer to the Log-based Incremental Replication documentation for more info.

You can also use one of Stitch’s other Replication Methods, which don’t require any database configuration. Replication Methods can be changed at any time.

In this section:

Step 3.1: Install the wal2json plugin

To use Log-based Replication for your PostgreSQL integration, you must install the wal2json plugin. The wal2json plugin outputs JSON objects for logical decoding, which Stitch then uses to perform Log-based Replication.

Steps for installing the plugin vary depending on your operating system. Instructions for each operating system type are in the wal2json’s GitHub repository:

After you’ve installed the plugin, you can move onto the next step.

Step 3.2: Edit the client authentication file

Usually named pg_hba.conf, this file controls how clients authenticate to the PostgreSQL database. To ensure Stitch can read the output from the wal2json plugin, you’ll need to add replication connection rules to this file. These rules translate to “Allow the Stitch user from this IP address to perform replication on all the databases it has access to.”

  1. Log into your PostgreSQL server as a superuser.
  2. Locate the pg_hba.conf file, usually stored in the database cluster’s data directory. You can also locate this file by checking the value of the hba_file server parameter.
  3. Add the following lines to pg_hba.conf:

    host replication [stitch_username] 52.23.137.21/32 md5
    host replication [stitch_username] 52.204.223.208/32 md5
    host replication [stitch_username] 52.204.228.32/32 md5
    host replication [stitch_username] 52.204.230.227/32 md5
    

    A rule for each of Stitch’s IP addresses must be added to pg_hba.conf. As Stitch can use any one of these IP addresses to connect during the extraction process, each of them must have their own replication connection rule.

Step 3.3: Edit the database configuration file

Locate the database configuration file (usually postgresql.conf) and define the parameters as follows:

wal_level=logical
max_replication_slots=5
max_wal_senders=5

Note: For max_replication_slots and max_wal_senders, we’re defaulting to a value of 5. This should be sufficient unless you have a large number of read replicas connected to the master instance.

In the table below are the names, required values, and descriptions of the server settings you must define.

Setting Value Description
wal_level logical

Required to use Log-based Replication; available on PostgreSQL versions 9.4 and higher. Determines the level of information that is written to the write-ahead log (WAL).

A value of logical is required to use Log-based Replication. This level logs information needed to extract logical changesets - such as updates or deletes - and replicate data from the WAL.

max_replication_slots 5

Required to use Log-based Replication; available on PostgreSQL versions 9.4 and higher. Specifies the maximum number of replication slots that the server can support.

This must be greater than 1. If you have a large number of replica databases, you may want to increase the value of this parameter.

max_wal_senders 5

Available on PostgreSQL versions 9.4 and higher. Specifies the maximum number of concurrent connections from standby servers or streaming base backup clients (the maximum number of simultaneously running WAL sender processes).

If you have a large number of replica databases, you may want to define this setting during setup.

Step 3.4: Restart the PostgreSQL service

After you’ve finished editing the pg_hba.conf file and configuring the database settings, restart your PostgreSQL service to ensure the changes take effect.

Step 3.5: Create a replication slot

Next, you’ll create a dedicated logical replication slot for Stitch. In PostgreSQL, a logical replication slot represents a stream of database changes that can then be replayed to a client in the order they were made on the original server. Each slot streams a sequence of changes from a single database.

Note: Replication slots are specific to a given database in a cluster. If you want to connect multiple databases - whether in one integration or several - you’ll need to create a replication slot for each database.

  1. Log into the master database as a superuser.
  2. Using the wal2json plugin, create a logical replication slot:
    • If you’re connecting multiple databases, you’ll need to run this command for every database you want to connect, replacing <raw_database_name> with the name of the database:

      SELECT *
      FROM pg_create_logical_replication_slot('stitch_<raw_database_name>', 'wal2json');
      

      This will create a replication slot named stitch_<raw_database_name>.

    • If you’re connecting a single database, run the following command:

      SELECT *
      FROM pg_create_logical_replication_slot('stitch', 'wal2json');
      

      This will create a replication slot named stitch.

  3. Log in as the Stitch user and verify you can read from the replication slot, replacing <replication_slot_name> with the name of the replication slot:

    SELECT COUNT(*)
    FROM pg_logical_slot_peek_changes('<replication_slot_name>', null, null);
    

    If connecting multiple databases, you should verify that the Stitch user can read from each of the replication slots you created.

Note: wal2json is required to use Log-based replication in Stitch for PostgreSQL-backed databases.

Step 4: Connect Stitch

In this step, you’ll complete the setup by entering the database’s connection details and defining replication settings in Stitch.

Step 4.1: Define the database connection details

  1. If you aren’t signed into your Stitch account, sign in now.
  2. On the Stitch Dashboard page, click the Add Integration button.

  3. Locate and click the PostgreSQL icon.
  4. Fill in the fields as follows:

    • Integration Name: Enter a name for the integration. This is the name that will display on the Stitch Dashboard for the integration; it’ll also be used to create the schema in your destination.

      For example, the name “Stitch PostgreSQL” would create a schema called stitch_postgresql in the destination. Note: The schema name cannot be changed after the integration is saved.

    • Host (Endpoint): Enter the host address (endpoint) used by the PostgreSQL instance. For example: This could be a network address such as 192.68.0.1, or a server endpoint like dbname.hosting-provider.com.

    • Port: Enter the port used by the instance. The default is 5432.

    • Username: Enter the Stitch PostgreSQL database user’s username.

    • Password: Enter the password for the Stitch PostgreSQL database user.

    • Database: Enter the name of the PostgreSQL database you want to connect to Stitch. Stitch will ‘find’ all databases you give the Stitch user access to - a default database is only used to complete the connection. This is required for PostgreSQL integrations.

    • Include PostgreSQL schema names in destination tables: Checking this setting will include schema names from the source database in the destination table name - for example: <source_schema_name>__<table_name>.

      Stitch loads all selected replicated tables to a single schema, preserving only the table name. If two tables canonicalize to the same name - even if they’re in different source databases or schemas - name collision errors can arise. Checking this setting can prevent these issues.

      Note: This setting can not be changed after the integration is saved. Additionally, this setting may create table names that exceed your destination’s limits. For more info, refer to the Database Integration Table Name Collisions guide.

Step 4.2: Define the SSH connection details

If you’re using an SSH tunnel to connect your PostgreSQL database to Stitch, you’ll also need to define the SSH settings. Refer to the Setting up an SSH Tunnel for a database connection guide for assistance with completing these fields.

  1. Click the SSH Tunnel checkbox.

  2. Fill in the fields as follows:

    • SSH Host: Enter the public IP address or hostname of the server Stitch will SSH into.

    • SSH Port: Enter the SSH port on your server. (22 by default)

    • SSH User: Enter the Stitch Linux (SSH) user’s username.

Step 4.3: Define the SSL connection details

Click the Connect using SSL checkbox if you’re using an SSL connection. Note: The database must support and allow SSL connections for this setting to work correctly.

Step 4.4: Define the Log-based Replication setting

In the Log-based Replication section, you can set this as the integration’s default Replication Method.

When enabled, tables that are set to replicate will use Log-based Incremental Replication by default. If you don’t want a table to use Log-based Incremental Replication, you can change it in the Table Settings page for that table.

If this setting isn’t enabled, you’ll have to select a Replication Method for each table you set to replicate.

Step 4.5: Create a replication schedule

In the Replication Frequency section, you’ll create the integration’s replication schedule. An integration’s replication schedule determines how often Stitch runs a replication job, and the time that job begins.

PostgreSQL integrations support the following replication scheduling methods:

To keep your row usage low, consider setting the integration to replicate less frequently. See the Understanding and Reducing Your Row Usage guide for tips on reducing your usage.

Step 4.6: Save the integration

When finished, click Check and Save.

Stitch will perform a connection test to the PostgreSQL database; if successful, a Success! message will display at the top of the screen. Note: This test may take a few minutes to complete.

Step 5: Select data to replicate

The last step is to select the tables and columns you want to replicate.

Note: If a replication job is currently in progress, new selections won’t be used until the next job starts.

For PostgreSQL integrations, you can select:

  1. Individual tables and columns

  2. All tables and columns (except views)

  3. Database views

Click the tabs to view instructions for each selection method.

  1. In the Integration Details page, click the Tables to Replicate tab.
  2. Locate a table you want to replicate.
  3. Click the checkbox next to the table’s name. A blue checkmark means the table is set to replicate.

  4. After you set a table to replicate, a page with the table’s columns will display. De-select columns if needed.

  5. Next, you’ll define the table’s Replication Method. Click the Table Settings button.
  6. In the Table Settings page:
    1. Define the table’s Replication Method, or skip this step if you want to use the integration’s default method.

    2. If using Key-based Incremental Replication, select a Replication Key.

    3. When finished, click Update Settings.

  7. Repeat this process for every table you want to replicate.

  8. Click the Finalize Your Selections button at the bottom of the page to save your data selections.
  1. Click into the integration from the Stitch Dashboard page.
  2. Click the Tables to Replicate tab.

  3. Navigate to the table level, selecting any databases and/or schemas that contain tables you want to replicate.

  4. In the list of tables, click the box next to the Table Names column.
  5. In the menu that displays, click Track AllTables and Fields (Except Views):

    The Track AllTables and Fields (Except Views) menu in the Tables to Replicate tab

  6. Click the Finalize Your Selections button at the bottom of the page to save your data selections.

Setting a database view to replicate is similar to selecting a table, with a few differences. Refer to the Replicating Database Views guide for detailed instructions.

At a high level, you’ll need to complete the following to select a database view:

  1. Verify the database user’s permissions
  2. Select the view
  3. Optional: Define the view’s Primary Key
  4. Define the view’s Replication Method
  5. Save the view’s settings

Initial and historical replication jobs

After you finish setting up PostgreSQL, its Sync Status may show as Pending on either the Stitch Dashboard or in the Integration Details page.

For a new integration, a Pending status indicates that Stitch is in the process of scheduling the initial replication job for the integration. This may take some time to complete.

Free historical data loads

The first seven days of replication, beginning when data is first replicated, are free. Rows replicated from the new integration during this time won’t count towards your quota. Stitch offers this as a way of testing new integrations, measuring usage, and ensuring historical data volumes don’t quickly consume your quota.


Questions? Feedback?

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