Josh Howard, Senior Engineering Manager at Cloudflare, joins me to explain how Durable Objects and D1 work under the hood—and why Cloudflare’s approach to stateful serverless infrastructure is so unique. We get into V8 isolates, replication models, routing strategies, and even upcoming support for containers. 

Want to learn more about SQLite? Check out my SQLite course: https://highperformancesqlite.com/?ref=podcast 

Follow Josh: 
Twitter: https://twitter.com/ajoshhoward 
LinkedIn: https://www.linkedin.com/in/joshthoward 

Follow Aaron: 
Twitter: https://twitter.com/aarondfrancis 
LinkedIn: https://www.linkedin.com/in/aarondfrancis 
Website: https://aaronfrancis.com - find articles, podcasts, courses, and more.

Database school on YouTube: https://www.youtube.com/playlist?list=PLI72dgeNJtzqElnNB6sQoAn2R-F3Vqm15
Database school audio only: https://databaseschool.transistor.fm 

Chapters 
00:00 - Intro 
00:37 - What is a Durable Object? 
01:43 - Cloudflare’s serverless model and V8 isolates 
03:58 - Why stateful serverless matters 
05:14 - Durable Objects vs Workers 
06:22 - How routing to Durable Objects works 
08:01 - What makes them "durable"? 
08:51 - Tradeoffs of colocating compute and state 
10:58 - Stateless Durable Objects 
12:49 - Waking up from sleep and restoring state 
16:15 - Durable Object storage: KV and SQLite APIs 
18:49 - Relationship between D1, Workers KV, and DOs 
20:34 - Performance of local storage writes 
21:50 - Storage replication and output gating 
24:15 - Lifecycle of a request through a Durable Object 
26:46 - Replication strategy and long-term durability 
31:25 - Placement logic and sharding strategy 
36:35 - Use cases: agents, multiplayer games, chat apps 
40:33 - Scaling Durable Objects 
41:14 - Globally unique ID generation 
43:22 - Named Durable Objects and coordination 
46:07 - D1 vs Workers KV vs Durable Objects 
47:50 - Outerbase acquisition and DX improvements 
49:49 - Querying durable object storage 
51:20 - Developer Week highlights and new features 
52:44 - Read replicas and sticky sessions 
53:49 - Containers and the future of routing 
56:47 - Deployment regions and infrastructure expansion 
57:43 - Hiring and how to connect with Josh