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Storage Engine

The storage-engine service is the canonical authority for hot-tier data and core MQL semantics.

Responsibilities​

  • WAL-backed durable writes
  • Hot-tier document and index storage
  • Query filter evaluation
  • Update operator execution
  • Aggregation stage execution (including Thermocline extensions)
  • MVCC snapshot/time-travel handling

Key Modules (Code)​

  • services/storage-engine/src/engine.rs
  • services/storage-engine/src/filter/
  • services/storage-engine/src/aggregation/
  • services/storage-engine/src/index/
  • services/storage-engine/src/mvcc/
  • services/storage-engine/src/wal/

Write Path (Hot Tier)​

  1. Gateway routes write commands to storage-engine.
  2. WAL append occurs before commit acknowledgment.
  3. In-memory structures and on-disk structures are updated.
  4. Change-stream eventing and cursor wakeups are emitted through gateway integration.

Indexes​

Storage-engine handles index creation/list/drop and index-backed evaluation through command routes:

  • createIndexes
  • dropIndexes
  • listIndexes

See Supported Operations for command-level coverage.