`log2`

Generic Description

Computes a base-2 logarithm for positive numeric values. It is documented separately because numeric transforms change ranking, thresholds, and buckets in ways planner tools must not guess.

Simple example:

RETURN log2(8.0) AS value

Consumer-Level Explanation

Use it for doubling-scale interpretations such as capacity, fanout, or binary growth. Prefer this function when the transformation is a deliberate part of the model or report, and name the derived value in a WITH stage when it will be reused.

More Detailed Explanation

log2 is scalar math, so it is evaluated per row after graph patterns, procedure output, or map projections have produced values. Keep it close to the query when thresholds, ranking, and derived fields need to be auditable and reproducible.

Advanced Example

This example applies log2 to a named score component after matching graph data, making the derived metric reviewable before ordering.

MATCH (d:Document)
WITH d, properties(d).prize + 1.0 AS adjusted_priority
RETURN d.title AS document,
       log2(adjusted_priority) AS doubling_scale_priority
ORDER BY doubling_scale_priority DESC

Real Use Cases

• distance-from-target scoring
• numeric bucketing and normalization before ORDER BY or aggregation
• making scoring formulas visible to query review and assistant tooling

Real Limitations And Tradeoffs

• invalid numeric inputs produce null-like results rather than a repaired value
• math functions do not fix poor feature scaling; choose transformations intentionally
• nondeterministic functions such as random sampling are not appropriate for persisted decisions