Pulse Documentation

name: type-categorical-u16
kind: type
description: 2-byte categorical with inline dictionary up to 65,536 labels.
type: reference
applies_to: inspect, predict

Bytes

Fixed-width: 2 bytes per record (dictionary index, little-endian). Not bit-packed. Stride contributes 2 bytes to Schema.RecordByteSize. The inline dictionary block lives in the schema.

Range

MaxCategoricalEntries() = 65,536 distinct labels. Right-sized for medium-cardinality enums — city, product SKU within a department, vendor codes. Overflow on import → PULSE_IMPORT_CATEGORICAL_OVERFLOW; shard insert past the width → PULSE_SHARD_DICT_WIDTH_OVERFLOW.

Null

Orthogonal. Nullable: true participates in the per-record null bitmap. Index 0 is the first dictionary entry, never null. IsCategorical() is true; default aggregator is AGG_MODE_COUNT; default grouper is GROUP_CATEGORY.

Dictionary

Present (HasDictionary() = true). Inline schema block; MaxDictEntries() = 65,536. Shard cohesion: union-merge — incoming records byte-rewritten with remapped indices when canonical dict diverges.

See

• Skill: cohort-schema-design (Field-type matrix, Width overflow, Sharded cohorts — Cohesion).
• Cross-link: type-set-u16 for multi-select up to 16 distinct labels.