Module aggregate_helpers 

Public helpers for streaming aggregate accumulators.

These thin wrappers expose field-extraction primitives used by the handlers/aggregate.rs streaming accumulator path in the nodedb crate. Each function operates on a single raw MessagePack document byte slice and returns only the scalar value needed by the calling accumulator — no document bytes are retained after the call returns.

Functions

extract_bytes

Extract a field or expression result as raw msgpack bytes. Used by count_distinct, approx_count_distinct, approx_topk, etc.

extract_f64

Extract a numeric (f64) value from field, or evaluate expr if provided. Returns None when the field is absent or cannot be converted to f64.

extract_non_null

Returns Some(()) when the field is present and non-null. Used by count(field) accumulator to count non-null values.

extract_str

Extract a display string from field, or evaluate expr if provided. Returns None when the field is absent.

extract_value

Extract a field as Value. Uses direct msgpack→Value for scalars; falls back to full document decode only for complex types.