Simon Willison’s Weblog

9 items tagged “benjohnson”


[On SQLite for production concurrent writes] In general, WAL mode “just works” as Simon said. You just need to make sure you don’t have long running write transactions, although those are somewhat problematic in any database system. Don’t do stuff like starting a write txn and then calling a remote API and then committing. That’ll kill your write throughout.

Ben Johnson # 26th January 2023, 7:36 pm


Introducing LiteFS (via) LiteFS is the new SQLite replication solution from Fly, now ready for beta testing. It’s from the same author as Litestream but has a very different architecture; LiteFS works by implementing a custom FUSE filesystem which spies on SQLite transactions being written to the journal file and forwards them on to other nodes in the cluster, providing full read-replication. The signature Litestream feature of streaming a backup to S3 should be coming within the next few months. # 21st September 2022, 6:56 pm

How the SQLite Virtual Machine Works. The latest entry in Ben Johnson’s series about SQLite internals. # 7th September 2022, 8:49 pm

How SQLite Scales Read Concurrency (via) Ben Johnson’s series on SQLite internals continues—this time with a detailed explanation of how the SQLite WAL (Write-Ahead Log) is implemented. # 24th August 2022, 4:16 pm

How SQLite Helps You Do ACID (via) Ben Johnson’s series of posts explaining the internals of SQLite continues with a deep look at how the rollback journal works. I’m learning SO much from this series. # 10th August 2022, 3:39 pm

SQLite Internals: Pages & B-trees (via) Ben Johnson provides a delightfully clear introduction to SQLite internals, describing the binary format used to store rows on disk and how SQLite uses 4KB pages for both row storage and for the b-trees used to look up records. # 27th July 2022, 2:57 pm

SQLite Happy Hour—a Twitter Spaces conversation about three interesting projects building on SQLite

Yesterday I hosted SQLite Happy Hour. my first conversation using Twitter Spaces. The idea was to dig into three different projects that were doing interesting things on top of SQLite. I think it worked pretty well, and I’m curious to explore this format more in the future.

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Litestream runs continuously on a test server with generated load and streams backups to S3. It uses physical replication so it’ll actually restore the data from S3 periodically and compare the checksum byte-for-byte with the current database.

Ben Johnson # 11th February 2021, 8:50 pm

Why I Built Litestream. Litestream is a really exciting new piece of technology by Ben Johnson, who previously built BoltDB, the key-value store written in Go that is used by etcd. It adds replication to SQLite by running a process that converts the SQLite WAL log into a stream that can be saved to another folder or pushed to S3. The S3 option is particularly exciting—Ben estimates that keeping a full point-in-time recovery log of a high write SQLite database should cost in the order of a few dollars a month. I think this could greatly expand the set of use-cases for which SQLite is sensible choice. # 11th February 2021, 7:25 pm