Real-World Datomic - An Experience Report

Explore a comprehensive experience report on implementing and optimizing Datomic in a real-world production system during this 41-minute conference talk from Strange Loop 2013. Gain deep insights into Datomic's indexing process, schema design, query behavior, and transactor operational characteristics. Learn how to leverage Datomic's architecture for solving complex problems, illustrated through a practical sales funnel event tracking system. Discover the intricacies of Datomic's data model, event capture techniques, and efficient data storage and retrieval mechanisms. Delve into advanced topics such as index storage, segment management, and entity ID anatomy. Suitable for both Datomic beginners and experienced users, this talk provides valuable knowledge for optimizing Datomic implementations in production environments.

Intro
The Problem • Provide a summary of sales funnel events for Room Key • Users move through the website impression - hotel details - lead - booking . Want per-day event counts by hotel & event type
Datomic's Architecture
Datomic's Data Model
Capturing Events - Schema Type Qualifiers
Capturing Events - Example
Capturing Events - Refs
Storing and Retrieving Data in Datomic • One or more EAV tuples submitted to the transactor All are given the same value . Datoms written transactionally to the log . All datoms also stored redundantly in the indexes
EAVT and AEVT
Capturing Events - EAVT
AVET and VAET
Index Storage and Retrieval . Datoms are stored in compressed chunks called segments • Segments are stored as a tree • Segments are immutable once written • Each transaction conceptually creates a new root
Indexing - Append
Anatomy of an Entity ID
A Change In Approach
The Code