sqlite

Shape: B-tree, full SQL, pure Go (modernc build) Repository: modernc.org/sqlite

sqlite is not really a key/value store, it is a full relational database, measured here through a two-column table used as one. That framing explains both ends of its results: on raw get and put it is the slowest engine here, because it is paying for a SQL layer the others do not have, and on durable writes it is the fastest, because that same mature engine practices group commit.

This is the pure-Go modernc build, so it adds no cgo and runs anywhere Go runs.

Best at

• Durable writes. 17,000 durable writes/sec, tied for the top through group commit. See durable writes.
• Actual SQL. Joins, indexes, transactions, schemas, the whole relational toolkit, if your data wants more than key/value.

Watch out for

• Slow raw key/value ops. 45,000 reads/sec and 29,000 writes/sec, the slowest here by a wide margin. The SQL machinery is overhead you do not want if all you need is get and put.
• Space. 4.5x the data, page and index overhead.

Reach for it when

Your data is relational, or will be: you want queries, joins, and a schema, not just keyed blobs. Or when you need durable writes under concurrency and value a battle-tested engine. If you genuinely only need key/value, every other engine here is faster; pick one of them and keep sqlite for when the data grows relationships.