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Singer.io target for loading data to Snowflake - PipelineWise compatible

Project description

pipelinewise-target-snowflake

PyPI version PyPI - Python Version License: Apache2

Singer target that loads data into Snowflake following the Singer spec.

This is a PipelineWise compatible target connector.

How to use it

The recommended method of running this target is to use it from PipelineWise. When running it from PipelineWise you don't need to configure this tap with JSON files and most of things are automated. Please check the related documentation at Target Snowflake

If you want to run this Singer Target independently please read further.

Install

First, make sure Python 3 is installed on your system or follow these installation instructions for Mac or Ubuntu.

It's recommended to use a virtualenv:

  python3 -m venv venv
  pip install pipelinewise-target-snowflake

or

  python3 -m venv venv
  . venv/bin/activate
  pip install --upgrade pip
  pip install .

Flow diagram

Flow Diagram

To run

Like any other target that's following the singer specificiation:

some-singer-tap | target-snowflake --config [config.json]

It's reading incoming messages from STDIN and using the properites in config.json to upload data into Snowflake.

Note: To avoid version conflicts run tap and targets in separate virtual environments.

Pre-requirements

You need to create two objects in snowflake in one schema before start using this target.

  1. A named external stage object on S3. This will be used to upload the CSV files to S3 and to MERGE data into snowflake tables.
CREATE STAGE {schema}.{stage_name}
url='s3://{s3_bucket}'
credentials=(AWS_KEY_ID='{aws_key_id}' AWS_SECRET_KEY='{aws_secret_key}')
encryption=(MASTER_KEY='{client_side_encryption_master_key}');

The encryption option is optional and used for client side encryption. If you want client side encryption enabled you'll need to define the same master key in the target config.json. Furhter details below in the Configuration settings section.

  1. A named file format. This will be used by the MERGE/COPY commands to parse the CSV files correctly from S3:

CREATE file format IF NOT EXISTS {schema}.{file_format_name} type = 'CSV' escape='\\' field_optionally_enclosed_by='"';

Configuration settings

Running the the target connector requires a config.json file. Example with the minimal settings:

{

  "account": "rtxxxxx.eu-central-1",
  "dbname": "database_name",
  "user": "my_user",
  "password": "password",
  "warehouse": "my_virtual_warehouse",
  "aws_access_key_id": "secret",
  "aws_secret_access_key": "secret",
  "s3_bucket": "bucket_name",
  "stage": "snowflake_external_stage_object_name",
  "file_format": "snowflake_file_format_object_name",
  "default_target_schema": "my_target_schema"
}

Full list of options in config.json:

Property Type Required? Description
account String Yes Snowflake account name (i.e. rtXXXXX.eu-central-1)
dbname String Yes Snowflake Database name
user String Yes Snowflake User
password String Yes Snowflake Password
warehouse String Yes Snowflake virtual warehouse name
aws_access_key_id String Yes S3 Access Key Id
aws_secret_access_key String Yes S3 Secret Access Key
s3_bucket String Yes S3 Bucket name
s3_key_prefix String (Default: None) A static prefix before the generated S3 key names. Using prefixes you can upload files into specific directories in the S3 bucket.
stage String Yes Named external stage name created at pre-requirements section. Has to be a fully qualified name including the schema name
file_format String Yes Named file format name created at pre-requirements section. Has to be a fully qualified name including the schema name.
batch_size_rows Integer (Default: 100000) Maximum number of rows in each batch. At the end of each batch, the rows in the batch are loaded into Snowflake.
flush_all_streams Boolean (Default: False) Flush and load every stream into Snowflake when one batch is full. Warning: This may trigger the COPY command to use files with low number of records, and may cause performance problems.
parallelism Integer (Default: 0) The number of threads used to flush tables. 0 will create a thread for each stream, up to parallelism_max. -1 will create a thread for each CPU core. Any other positive number will create that number of threads, up to parallelism_max.
parallelism_max Integer (Default: 16) Max number of parallel threads to use when flushing tables.
default_target_schema String Name of the schema where the tables will be created. If schema_mapping is not defined then every stream sent by the tap is loaded into this schema.
default_target_schema_select_permission String Grant USAGE privilege on newly created schemas and grant SELECT privilege on newly created tables to a specific role or a list of roles. If schema_mapping is not defined then every stream sent by the tap is granted accordingly.
schema_mapping Object Useful if you want to load multiple streams from one tap to multiple Snowflake schemas.

If the tap sends the stream_id in <schema_name>-<table_name> format then this option overwrites the default_target_schema value. Note, that using schema_mapping you can overwrite the default_target_schema_select_permission value to grant SELECT permissions to different groups per schemas or optionally you can create indices automatically for the replicated tables.

Note: This is an experimental feature and recommended to use via PipelineWise YAML files that will generate the object mapping in the right JSON format. For further info check a [PipelineWise YAML Example]
disable_table_cache Boolean (Default: False) By default the connector caches the available table structures in Snowflake at startup. In this way it doesn't need to run additional queries when ingesting data to check if altering the target tables is required. With disable_table_cache option you can turn off this caching. You will always see the most recent table structures but will cause an extra query runtime.
client_side_encryption_master_key String (Default: None) When this is defined, Client-Side Encryption is enabled. The data in S3 will be encrypted, No third parties, including Amazon AWS and any ISPs, can see data in the clear. Snowflake COPY command will decrypt the data once it's in Snowflake. The master key must be 256-bit length and must be encoded as base64 string.
client_side_encryption_stage_object String (Default: None) Required when client_side_encryption_master_key is defined. The name of the encrypted stage object in Snowflake that created separately and using the same encryption master key.
add_metadata_columns Boolean (Default: False) Metadata columns add extra row level information about data ingestions, (i.e. when was the row read in source, when was inserted or deleted in snowflake etc.) Metadata columns are creating automatically by adding extra columns to the tables with a column prefix _SDC_. The column names are following the stitch naming conventions documented at https://www.stitchdata.com/docs/data-structure/integration-schemas#sdc-columns. Enabling metadata columns will flag the deleted rows by setting the _SDC_DELETED_AT metadata column. Without the add_metadata_columns option the deleted rows from singer taps will not be recongisable in Snowflake.
hard_delete Boolean (Default: False) When hard_delete option is true then DELETE SQL commands will be performed in Snowflake to delete rows in tables. It's achieved by continuously checking the _SDC_DELETED_AT metadata column sent by the singer tap. Due to deleting rows requires metadata columns, hard_delete option automatically enables the add_metadata_columns option as well.
data_flattening_max_level Integer (Default: 0) Object type RECORD items from taps can be loaded into VARIANT columns as JSON (default) or we can flatten the schema by creating columns automatically.

When value is 0 (default) then flattening functionality is turned off.
primary_key_required Boolean (Default: True) Log based and Incremental replications on tables with no Primary Key cause duplicates when merging UPDATE events. When set to true, stop loading data if no Primary Key is defined.

To run tests:

  1. Define environment variables that requires running the tests
  export TARGET_SNOWFLAKE_ACCOUNT=<snowflake-account-name>
  export TARGET_SNOWFLAKE_DBNAME=<snowflake-database-name>
  export TARGET_SNOWFLAKE_USER=<snowflake-user>
  export TARGET_SNOWFLAKE_PASSWORD=<snowfale-password>
  export TARGET_SNOWFLAKE_WAREHOUSE=<snowflake-warehouse>
  export TARGET_SNOWFLAKE_SCHEMA=<snowflake-schema>
  export TARGET_SNOWFLAKE_AWS_ACCESS_KEY=<aws-access-key-id>
  export TARGET_SNOWFLAKE_AWS_SECRET_ACCESS_KEY=<aws-access-secret-access-key>
  export TARGET_SNOWFLAKE_S3_BUCKET=<s3-external-bucket>
  export TARGET_SNOWFLAKE_S3_KEY_PREFIX=<bucket-directory>
  export TARGET_SNOWFLAKE_STAGE=<stage-object-with-schema-name>
  export TARGET_SNOWFLAKE_FILE_FORMAT=<file-format-object-with-schema-name>
  export CLIENT_SIDE_ENCRYPTION_MASTER_KEY=<client_side_encryption_master_key>
  export CLIENT_SIDE_ENCRYPTION_STAGE_OBJECT=<client_side_encryption_stage_object>
  1. Install python test dependencies in a virtual env and run nose unit and integration tests
  python3 -m venv venv
  . venv/bin/activate
  pip install --upgrade pip
  pip install .[test]
  1. To run unit tests:
  nosetests --where=tests/unit
  1. To run integration tests:
  nosetests --where=tests/integration

To run pylint:

  1. Install python dependencies and run python linter
  python3 -m venv venv
  . venv/bin/activate
  pip install --upgrade pip
  pip install .
  pip install pylint
  pylint target_snowflake -d C,W,unexpected-keyword-arg,duplicate-code

License

Apache License Version 2.0

See LICENSE to see the full text.

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