Tap PostgreSQL

PostgreSQL setup requirements

Step 1: Check if you have all the required credentials for replicating data from PostgreSQL

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

Step 2. Create a PipelineWise database user

Next, you’ll create a dedicated database user for PipelineWise. Create a new user and grant the required permissions on the database, schema and tables that you want to replicate:

  • CREATE USER pipelinewise WITH ENCRYPTED PASSWORD '<password>'

  • GRANT CONNECT ON DATABASE <database_name> TO pipelinewise

  • GRANT USAGE ON SCHEMA <schema_name> TO pipelinewise

  • GRANT SELECT ON ALL TABLES IN SCHEMA <schema_name> TO pipelinewise

In order for pipelinewise user to automatically be able to access any tables created in the future, we recommend running the following query:

ALTER DEFAULT PRIVILEGES IN SCHEMA <schema_name> GRANT SELECT ON TABLES TO pipelinewise;

Step 3: Configure Log-based Incremental Replication

Note

This step is only required if you use Log Based replication method.

Warning

Log Based for PostgreSQL-based databases requires:

  • PostgreSQL databases running PostgreSQL versions 9.4.x or greater.

  • To avoid a critical PostgreSQL bug, use at least one of the following minor versions

    • PostgreSQL 12.0

    • PostgreSQL 11.2

    • PostgreSQL 10.7

    • PostgreSQL 9.6.12

    • PostgreSQL 9.5.16

    • PostgreSQL 9.4.21

  • A connection to the master instance. Log-based replication will only work by connecting to the master instance.

Step 3.1: Install the wal2json plugin

To use Log Based for your PostgreSQL integration, you must install the wal2json plugin that has support for format-version=2 (wal2json >= 2.3). The wal2json plugin outputs JSON objects for logical decoding, which the tap 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 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.

Step 3.3: Restart the PostgreSQL service

Restart your PostgreSQL service to ensure the changes take effect.

Step 3.4: Replication slot

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.

Pipelinewise automatically creates a dedicated logical replication slot for each database and tap.

Note

wal2json is required to use Log Based in Pipelinewise for PostgreSQL-backed databases.

Note

In case of full resync of a whole tap, Pipelinewise will attempt to drop the slot.

Configuring what to replicate

PipelineWise configures every tap with a common structured YAML file format. A sample YAML for Postgres replication can be generated into a project directory by following the steps in the Generating Sample Pipelines section.

Example YAML for tap-postgres:

---

# ------------------------------------------------------------------------------
# General Properties
# ------------------------------------------------------------------------------
id: "postgres_sample"                  # Unique identifier of the tap
name: "Sample Postgres Database"       # Name of the tap
type: "tap-postgres"                   # !! THIS SHOULD NOT CHANGE !!
owner: "somebody@foo.com"              # Data owner to contact
#send_alert: False                     # Optional: Disable all configured alerts on this tap
#slack_alert_channel: "#tap-channel"   # Optional: Sending a copy of specific tap alerts to this slack channel


# ------------------------------------------------------------------------------
# Source (Tap) - PostgreSQL connection details
# ------------------------------------------------------------------------------
db_conn:
  host: "<HOST>"                       # PostgreSQL host
  port: 5432                           # PostgreSQL port
  user: "<USER>"                       # PostfreSQL user
  password: "<PASSWORD>"               # Plain string or vault encrypted
  dbname: "<DB_NAME>"                  # PostgreSQL database name
  #filter_schemas: "schema1,schema2"   # Optional: Scan only the required schemas
                                       #           to improve the performance of
                                       #           data extraction
  #max_run_seconds                     # Optional: Stop running the tap after certain
                                       #           number of seconds
                                       #           Default: 43200
  #logical_poll_total_seconds:         # Optional: Stop running the tap when no data
                                       #           received from wal after certain number of seconds
                                       #           Default: 10800
  #break_at_end_lsn:                   # Optional: Stop running the tap if the newly received lsn
                                       #           is after the max lsn that was detected when the tap started
                                       #           Default: true
  #ssl: "true"                         # Optional: Using SSL via postgres sslmode 'require' option.
                                       #           If the server does not accept SSL connections or the client
                                       #           certificate is not recognized the connection will fail
  fastsync_parallelism: <int>          # Optional: size of multiprocessing pool used by FastSync
                                       #           Min: 1
                                       #           Default: number of CPU cores

# ------------------------------------------------------------------------------
# Destination (Target) - Target properties
# Connection details should be in the relevant target YAML file
# ------------------------------------------------------------------------------
target: "snowflake"                    # ID of the target connector where the data will be loaded
batch_size_rows: 20000                 # Batch size for the stream to optimise load performance
stream_buffer_size: 0                  # In-memory buffer size (MB) between taps and targets for asynchronous data pipes
#batch_wait_limit_seconds: 3600        # Optional: Maximum time to wait for `batch_size_rows`. Available only for snowflake target.

# Options only for Snowflake target
#split_large_files: False                       # Optional: split large files to multiple pieces and create multipart zip files. (Default: False)
#split_file_chunk_size_mb: 1000                 # Optional: File chunk sizes if `split_large_files` enabled. (Default: 1000)
#split_file_max_chunks: 20                      # Optional: Max number of chunks if `split_large_files` enabled. (Default: 20)
#archive_load_files: False                      # Optional: when enabled, the files loaded to Snowflake will also be stored in `archive_load_files_s3_bucket`
#archive_load_files_s3_prefix: "archive"        # Optional: When `archive_load_files` is enabled, the archived files will be placed in the archive S3 bucket under this prefix.
#archive_load_files_s3_bucket: "<BUCKET_NAME>"  # Optional: When `archive_load_files` is enabled, the archived files will be placed in this bucket. (Default: the value of `s3_bucket` in target snowflake YAML)


# ------------------------------------------------------------------------------
# Source to target Schema mapping
# ------------------------------------------------------------------------------
schemas:

  - source_schema: "public"            # Source schema in postgres with tables
    target_schema: "repl_pg_public"    # Target schema in the destination Data Warehouse
    target_schema_select_permissions:  # Optional: Grant SELECT on schema and tables that created
      - grp_stats

    # List of tables to replicate from Postgres to destination Data Warehouse
    #
    # Please check the Replication Strategies section in the documentation to understand the differences.
    # For LOG_BASED replication method you might need to adjust the source mysql/ mariadb configuration.
    tables:
      - table_name: "table_one"
        replication_method: "INCREMENTAL"   # One of INCREMENTAL, LOG_BASED and FULL_TABLE
        replication_key: "last_update"      # Important: Incremental load always needs replication key

        # OPTIONAL: Load time transformations
        #transformations:
        #  - column: "last_name"            # Column to transform
        #    type: "SET-NULL"               # Transformation type

      # You can add as many tables as you need...
      - table_name: "table_two"
        replication_method: "LOG_BASED"     # Important! Log based must be enabled in MySQL

  # You can add as many schemas as you need...
  # Uncomment this if you want replicate tables from multiple schemas
  #- source_schema: "another_schema_in_postgres"
  #  target_schema: "another