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Release notes

What each doc release contains.

The authoritative, commit-level history lives in CHANGELOG.md and on the releases page. This page summarises each version.

v0.1.0

The first public release. doc is feature-complete across milestones M0 through M9. It is pre-1.0, so the library API is still settling toward 1.0; see the stability page for what that means.

What a .doc file and binary give you:

  • The MongoDB document model and query language. BSON documents in collections with ObjectId _ids, the MQL comparison, logical, element, and array operators, dotted-path access with array fan-out, MongoDB null and missing semantics, and the BSON cross-type total order.
  • A driver-shaped Go API. Open returns a DB; Database and Collection walk down to the same InsertOne, Find, UpdateMany, ReplaceOne, BulkWrite, FindOneAndUpdate, Distinct, Aggregate, and index-view methods the official MongoDB Go driver exposes, with matching result types and cursors.
  • The aggregation pipeline. $match, $project, $group with the accumulators, $sort, $skip, $limit, $unwind, and $lookup including the MongoDB 5.0 pipeline form.
  • Indexes and a planner. Single-field, compound, multikey, unique, sparse, partial, and TTL indexes, maintained on the commit path, with order-preserving key encoding and a cost-based planner that chooses between collection, index, and covered scans, with Explain.
  • Transactions. Multi-document, multi-collection transactions through sessions, under snapshot isolation by default or serializable (SSI) on request, on an MVCC core where readers never block writers.
  • Durability and recovery. A WAL-mode pager with a 2Q buffer pool and group commit, crash recovery to the last committed transaction, online backup, incremental backup, WAL archiving, and point-in-time restore.
  • A MongoDB wire server. doc <file> serve answers the wire protocol so mongosh and the official Go, Node, and Python drivers connect unchanged, with SCRAM-SHA-256 authentication, role-based access control, TLS including x509, wire compression, and wire-level sessions and transactions.
  • Operational tooling. validate, compact, checkpoint, vacuum, backup, restore, import, export, dump, load, stats, schema, and rekey, plus an interactive mongosh-style shell.
  • At-rest encryption. Page-level encryption with a passphrase or a raw key, and rekey to rotate it.
  • Hardening. A fuzz suite over the BSON codec, the MQL parser, the update operators, and WAL replay; property tests for MVCC snapshot isolation and recovery; and a crash-injection recovery campaign.
  • A versioned, forward-checked file format. The header records a format major and minor version. A file whose major version is newer than the build is rejected with a clear error instead of misread, so an upgrade is safe.

How it was built

The engine was built bottom-up across ten milestones, each compiled, tested, and benchmarked before the next:

  • M0 the file format, the storage SPI seam, the WAL substrate, and the WAL-mode pager with a 2Q buffer pool.
  • M1 the slotted-page record store with durable inserts and the _id B-tree.
  • M2 the BSON codec, the snapshot-isolation MVCC core, and the Collection layer, verified against live MongoDB.
  • M3 the read query path (MQL, projection, sort, skip, limit), the document-mutation write path (the update operators, updateOne/updateMany/replaceOne, the find-and-modify family, distinct), and secondary indexes with the cost-based planner.
  • M4 array updates and $setOnInsert, bulk writes and upsert, and the aggregation pipeline.
  • M5 sessions and multi-document transactions, serializable snapshot isolation, and the linearizability corpus.
  • M6 the multi-collection engine, the public library API, document validation, capped and TTL collections, and the CLI and shell.
  • M7 observability, online checkpoint and vacuum, online backup, WAL archiving and point-in-time recovery, and the bench and soak harnesses.
  • M8 the full MongoDB wire server: framing and handshake, the data commands and compression, authentication and RBAC, TLS and at-rest encryption, wire sessions and transactions, and driver-compatibility checks.
  • M9 hardened fuzz corpora, $lookup with a pipeline, the columnar projection store, crash and recovery at scale, the performance polish, and this first release.
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