Detailed Design of the Typeahead Suggestion System

Detailed design

The illustration below outlines the flow and interaction of the system components. The design consists of two main parts:

• Suggestion service

• Assembler

Suggestion service

As a user types a query, getSuggestions(prefix) API calls reach the suggestion service. The service retrieves up to ten eligible candidates from Redis, using a key that includes the normalized prefix, locale, and relevant index version. On a miss, read the serving trie or another prepared index, then populate the cache. Aggregated counts in Cassandra are build inputs, not a reason to rebuild a trie during a user request.

Assembler