• (Formerly: Discovery AI)
  • Goal: significantly enhance shopping experience of individual buyers on e-commerce sites
  • Highly relevant and personalised product recommendations and search results
  • Multi-modal:
    • Recommendations AI
    • Retail Search
    • Vision API Product Search
      • Use images as search query

Recommendations AI

  • Improve conversion, click through rates, conversion
  • Looks at: browsing behaviour on-site, current context, SKUs available in catalog
  • Personalised and relevant search results
    • Understands intent and context
  • Features:
    • Advanced query understanding—returns product and category pages for broad queries, including non-product searches
    • Semantic search—extract product attributes and match with website content, classify products and grouping of info
    • Optimise and control—optimise results, ranking, meet business goals
    • Security and privacy—all data isolated and private

Retail API

  • Required to understand recommendations and search
  • Common endpoint
  • Ingest and manage input data
  • Request predictions based on data
  • Same ingested data used for recommendations and search
  • Fully managed
  • Global

Project Phases and Timelines

  1. Collect customer data
    • Obtain product catalog data
    • Capture user event data
    • 90 days
  2. Ingest customer data
    • Ingest catalog
    • Ingest historical events
    • Configure real-time events (GTM, JS pixel)
    • Duration varies
  3. Train models
    • Select models
    • Train
    • 1–4 days
  4. Integrate predictions
    • Integrate API into site, emails etc.
    • Set up recommendations token and experiment ID
    • Duration varies
  5. A/B testing
    • Duration varies

Data Ingestion


  • Collection of product object
  • Catalog branches—test new data before promoting to live
    • Up to 3—named 0, 1 and 2
    • Live site points to default_branch—can change to 0, 1 or 2


  • Required:
    • id
    • title
  • Optional (partial list):
    • name
    • type
    • categories
    • description
    • attributes
    • tags
    • priceinfo
  • Key-value pairs
    • e.g. store name, colour etc.
    • Strong signals for recommendations model—highly recommended
  • System attributes
    • Predefined product fields
    • More info about product
    • e.g. size, colour, brand
  • Custom attributes
    • User-defined
  • Inventory-level attributes
    • Store-level info
    • Use for products where properties significantly change between stores and regions

Product Levels

  • Hierarchy
  • Choice: single of two-level catalog
  • Types:
    • Primary items
      • Can be individual items
      • Or groups of similar items (e.g. groups of sizes/colours)
    • Variant items
      • Can only be individual items (e.g. SKUs)
    • Collection items
      • Bundles of primary or variant items (Retail Search only)
  • Type is immutable
  • Considerations:
    • Current catalog structure
    • User events—primary or variant product IDs passed?
      • If primary, use single level catalog
      • If variant, consider how many user events will be recorded for each—need to ensure enough data for each
    • What is most useful to return in search results/recommendations? Primary or variant items?


  • Price—current and original
  • Availability—in stock, out of stock, back ordered, pre-ordered
  • Quantity available
  • Fulfilment info—click and collect, next day etc.
  • Levels:
    • Product—online inventory only
    • Local—brick and mortar store inventory


Google Merchant Center (GMC)
  • Why?
    • If already using
    • Minimal dev work
  • Caveats:
    • Lacks important attributes
    • Lack of custom fields
  • Use BigQuery Data Transfer Service to stage it BigQuery—daily
  • Why?
    • Data already in BigQuery, or can easily export to
  • Caveats:
    • Tricky get schema format correct
Cloud Storage
  • Why?
    • Easiest to implement
    • Preferred if not GMC or BigQuery
  • Caveats:
    • JSONL format—File is not a JSON file, one JSON structure per line, each line is a product, no line breaks allowed
Direct Ingest—API
  • Why?
    • Fast—no need to schedule
  • Caveats:
    • Limit to number of products
    • Not suitable for large catalogs

User Events

  • Examples:
    • add-to-cart
    • category-page-view
    • detail-page-view
    • home-page-view
    • purchase-complete
    • search
    • shopping-cart-page-view
  • Recommended to log all events
  • visitorId
    • Unique to each customer
    • Across sessions and devices
    • Don’t create manually
    • Options:
      • E-commerce user ID
      • GA client ID (device-scoped)


  • Need to record historical and real time user events
  • Bulk import historical events:
    • Cloud Storage
    • BigQuery
    • GA360
    • Inline—API
    • GA4 with BigQuery
  • Real time:
    • Javascript pixel
    • Google Tag Manager
    • Direct API call
  • Send in near-real time where possible
    • Personalisation of search <1 hr, recommendations much quicker
  • Unjoined events
    • Events with product ID not in the catalog
    • Common problem
    • Monitor—keep <5%
  • Alerts
    • Cloud monitoring predefined alerts
    • e.g. User event recording reduction, high events unjoined

How much Data?

  • Depends on recommendations model type and optimisation objective
  • <100 products
    • Not a good fit—not enough variety
  • 3 months’ events—all model types
    • Product page views
    • Home page views
    • Add to cart
  • ”Frequently bought together”
    • 1–2 years purchase history
  • 1 year of data for seasonality and trends in the model

Building Recommendation Models

Optimisation Objectives

  • Types:
    • Click through rate (CTR)
    • Conversion rate (CVR)
    • Revenue per session
  • Can’t change once model is trained—training takes up to 2 days, so need to decide early
  • Config options:
    • Diversification
      • Disabled by default
      • Maximum number of items recommended from each category
    • Price reranking
      • Order by relevance and price
    • Category matching
      • Only show products which share 1+ categories with context product
      • Can truncate deeply nested hierarchies to help match better
  • Serving configurations
    • Use to change advanced model configurations options
      • Even after training
      • Near-real time changes
      • e.g. edit diversification and price reranking config in near-real time

Model Types

  • Others you may like
    • Default objective: Click through rate (can change to conversion rate)
    • Can add price ranking and diversification
    • Display on product details, add-to-cart and cart pages
  • Frequently bought together
    • Not personalised
    • Works for single or lists of products
    • Default objective: revenue per order
    • Can add diversification (not recommended)
    • Display on add-to-cart and cart pages
  • Recommended for you
    • Predicts next product user most likely to interact with or purchase
    • Most personalised
    • Default objective: Click through rate (can change to conversion rate)
    • Can add price ranking and diversification
    • Display on all pages
  • Recently viewed
    • Not ML model
    • Chronological order of products viewed
  • Similar items
    • Products with similar attributes
    • Only uses info from catalog
    • Default objective: CTR
    • Not customisable
  • Buy it again
    • Predicts products customer bought once, and often bought on a regular cadence
    • Not customisable
    • Display on any page
  • On sale
    • Personalised
    • Encourage users to purchase discounted items
    • Default objective: CTR (can change to conversion)
  • Page-level optimisation
    • Optimises an entire page
    • Automatically selects content of each panel and determines order on page

Reference Architecture

Graph View