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name: type-u64
kind: type
description: 8-byte unsigned integer; for sub-day timestamps and very wide cardinals.
type: reference
applies_to: inspect, predict

Bytes

Fixed-width: 8 bytes per record, little-endian. Not bit-packed. Stride contributes 8 bytes to Schema.RecordByteSize; reader uses binary.LittleEndian.Uint64.

Range

0..2^64 − 1. The canonical home for sub-day timestamps stored as microseconds (or nanoseconds) since epoch — Pulse has no native sub-day temporal type, so the convention is u64 micros. Also fits very wide surrogate keys and hash-derived identifiers.

Null

Orthogonal. Nullable: true participates in the per-record null bitmap. 0 is the integer zero, never a sentinel. IsNumeric() and IsNumericForAnalytics() are both true; null-skip semantics apply.

Dictionary

Absent. There is no categorical_u64 (the u32 index already exceeds practical dictionary sizes) — labeled enums top out at categorical_u32.

See

  • Skill: cohort-schema-design (Field-type matrix, Selection heuristics — sub-day timestamps as u64 micros).
  • Cross-link: type-date for day-granularity dates.