JDBIN

30-second answer

JDBIN is a binary format designed for efficient reading from object storage.

1-minute answer

Its purpose is not to act as a general database server, but to optimize known read and query paths for immutable data.

Deeper answer

JDBIN may contain:

• segment tables
• indexes
• string pools
• materialized views

The Worker acts as a query planner that decides which byte ranges need to be fetched from R2.

JDBIN v0.1 file structure

According to the report, JDBIN v0.1 consists of a header, a segment table, and independent segment payloads.

Header

0x00 magic      char[5]  "JDBIN"
0x05 version    u16
0x07 flags      u16
0x09 endian     u8
0x10 seg_count  u32
0x14 seg_table  u64
0x1C file_size  u64
0x24 checksum   u32

Example segments

• data_page
• index_sorted
• query_plan
• string_pool_index
• string_pool_data
• materialized_top
• materialized_source
• materialized_timestamp

Key modeling decision

Title text is not stored inline in every row. Rows contain a reference into a string pool, which keeps data pages fixed-width and addressable by offset.