Feathr Quick Start Guide with Azure Synapse

Overview

In this tutorial, we use Feathr Feature Store to create a model that predicts NYC Yellow Taxi fares. The dataset comes from here.

The major problems Feathr solves are:

  1. Create, share and manage useful features from raw source data.
  2. Provide Point-in-time feature join to create training dataset to ensure no data leakage.
  3. Deploy the same feature data to online store to eliminate training and inference data skew.

Step 1: Provision cloud resources

First step is to provision required cloud resources if you want to use Feathr. Feathr provides a python based client to interact with cloud resources.

Feathr has native cloud integration. Here are the steps to use Feathr on Azure:

  1. Follow the Feathr ARM deployment guide to run Feathr on Azure. This allows you to quickly get started with automated deployment using Azure Resource Manager template. Alternatively, if you want to set up everything manually, you can checkout the Feathr CLI deployment guide to run Feathr on Azure. This allows you to understand what is going on and set up one resource at a time.

  2. Once the deployment is complete,run the Feathr Jupyter Notebook by clicking this button: Binder.
  3. You only need to change the specified Resource Prefix.

Step 2: Install Feathr

Install Feathr using pip:

pip install -U feathr

Or if you want to use the latest Feathr code from GitHub:

pip install git+https://github.com/feathr-ai/feathr.git#subdirectory=feathr_project

Step 3: Run the sample notebook

We’ve provided a self-contained sample notebook to act as the main content of this getting started guide. This documentation should be used more like highlights and further explanations of that demo notebook.

Step 4: Update Feathr config

In the sample notebook, you will see some settings like below. You should update those settings based on your environment, for example the spark runtime, synapse/databricks endpoint, etc.

# DO NOT MOVE OR DELETE THIS FILE

# version of API settings
api_version: 1
project_config:
  project_name: "feathr_getting_started"
  # Information that are required to be set via environment variables.
  required_environment_variables:
    # Redis password for your online store
    - "REDIS_PASSWORD"
    # Client IDs and Client Secret for the service principal. Read the getting started docs on how to get those information.

offline_store:
---
spark_config:
---
online_store:
---
feature_registry:

All the configurations can be overwritten by environment variables with concatenation of __ for different layers of this config file. For example, feathr_runtime_location for databricks config can be overwritten by setting SPARK_CONFIG__DATABRICKS__FEATHR_RUNTIME_LOCATION environment variable.

Another example would be overwriting Redis host with this config: ONLINE_STORE__REDIS__HOST. if you want to override this setting in a shell environment:

export ONLINE_STORE__REDIS__HOST=feathrazure.redis.cache.windows.net

Or set this in python:

os.environ['ONLINE_STORE__REDIS__HOST'] = 'feathrazure.redis.cache.windows.net'

Step 5: Setup environment variables

In the self-contained sample notebook, you also have to setup a few environment variables like below in order to access those cloud resources. You should be able to get those values from the first step.

These values can also be retrieved by using cloud key value store, such as Azure Key Vault:

import os
os.environ['REDIS_PASSWORD'] = ''

Please refer to A note on using azure key vault to store credentials for more details.

Step 6: Create features with Python APIs

In Feathr, a feature is viewed as a function, mapping from entity id or key, and timestamp to a feature value. There are more explanations in the sample notebook.

Step 7: Register feature definitions to the central registry 

from feathr import FeathrClient

client = FeathrClient()
client.register_features()
client.list_registered_features(project_name="feathr_getting_started")

Step 8: Create training data using point-in-time correct feature join

A training dataset usually contains entity id columns, multiple feature columns, event timestamp column and label/target column.

To create a training dataset using Feathr, one needs to provide a feature join configuration file to specify what features and how these features should be joined to the observation data. The feature join config file mainly contains:

  1. The path of a dataset as the ‘spine’ for the to-be-created training dataset. We call this input ‘spine’ dataset the ‘observation’ dataset. Typically, each row of the observation data contains: a) Column(s) representing entity id(s), which will be used as the join key to look up(join) feature value. b) A column representing the event time of the row. By default, Feathr will make sure the feature values joined have a timestamp earlier than it, ensuring no data leakage in the resulting training dataset. c) Other columns will be simply pass through onto the output training dataset.
  2. The key fields from the observation data, which are used to joined with the feature data.
  3. List of feature names to be joined with the observation data. The features must be defined in the feature definition configs.
  4. The time information of the observation data used to compare with the feature’s timestamp during the join.

Create training dataset via feature join:

from feathr import FeathrClient

# Requested features to be joined
feature_query = FeatureQuery(feature_list=["f_location_avg_fare"], key=[location_id])

# Observation dataset settings
settings = ObservationSettings(
    observation_path="abfss://green_tripdata_2020-04.csv",    # Path to your observation data
    event_timestamp_column="lpep_dropoff_datetime",           # Event timestamp field for your data, optional
    timestamp_format="yyyy-MM-dd HH:mm:ss")                   # Event timestamp format， optional

# Prepare training data by joining features to the input (observation) data.
# feature-join.conf and features.conf are detected and used automatically.
client.get_offline_features(observation_settings=settings,
                                   output_path="abfss://output.avro",
                                   feature_query=feature_query)

The following feature join config is used:

feature_query = [FeatureQuery(feature_list=["f_location_avg_fare"], key=["DOLocationID"])]
        settings = ObservationSettings(
            observation_path="abfss://{adls_fs_name}@{adls_account}.dfs.core.windows.net/demo_data/green_tripdata_2020-04.csv",
            output_path="abfss://{adls_fs_name}@{adls_account}.dfs.core.windows.net/demo_data/output.avro",
            event_timestamp_column="lpep_dropoff_datetime", timestamp_format="yyyy-MM-dd HH:mm:ss")
client.get_offline_features(feature_query=feature_query, observation_settings=settings)

Step 9: Materialize feature value into offline/online storage

While Feathr can compute the feature value from the feature definition on-the-fly at request time, it can also pre-compute and materialize the feature value to offline and/or online storage.

Step 10: Fetching feature value for online inference

For features that are already materialized by the previous step, their latest value can be queried via the client’s get_online_features or multi_get_online_features API.

client.get_online_features("nycTaxiDemoFeature", "265", ['f_location_avg_fare', 'f_location_max_fare'])
client.multi_get_online_features("nycTaxiDemoFeature", ["239", "265"], ['f_location_avg_fare', 'f_location_max_fare'])

Next steps