Module segment 

Unified Segment System

Implements the Growing → Sealed segment lifecycle pattern. Segments are the fundamental unit of storage that handle entities of all types.

Write Path

1. WAL write (durability)
2. Growing-segment entity storage in RAM (HashMap mode or flat-vector mode with epoch-published lock-free reads)
3. seal() freezes the growing segment into a Sealed segment and builds pruning summaries over the immutable data

Read Path

1. Growing segment entity storage (most recent writes)
2. Sealed segments (older, immutable, zone-map guarded)

Lifecycle

Growing (in-memory, accepts writes)
   ↓ seal() when full or manually triggered
Sealed (immutable, zone maps built)
   ↓ flush() for persistence
Flushed (on disk, can be mmap'd)
   ↓ archive() for cold storage
Archived (compressed, infrequently accessed)

Structs

ColZone

Tracks the min and max observed Value for one column in a segment. Used to skip segments that cannot satisfy a range or equality predicate.

GraphIndexCursor

One indexed key at a time, with an exclusive resume ID and a source-wide upper bound captured before any batch. MVCC is checked during live hydration.

GrowingSegment

Growing segment implementation (in-memory, writable)

MultiColZone

SegmentConfig

Configuration for segments

SegmentScanCursor

Stable append-only positions, bounded when a scan opens the segment.

SegmentStats

Segment statistics

Enums

GraphEntityKind

The two physical kinds used by graph materialization passes.

SegmentError

Segment error types

SegmentState

Segment state in its lifecycle

ZoneColPred

A predicate on a single column that can be checked against a ColZone.

ZoneColPredKind

Tag-only variant of ZoneColPred — used where the Value is stored separately.

Constants

CHECKPOINT_MUTATIONS_MAX

Maximum distinct dirty physical IDs tracked per segment and checkpoint projection.

SCAN_BATCH_SIZE

Maximum physical positions examined under one segment read guard.

Traits

UnifiedSegment

A unified segment that stores all entity types

Type Aliases

SegmentId

Unique identifier for a segment