Module topk 

Streaming Top-K Operator

Bounded heap of top-K items with retraction-based changelog emission.

Supports ORDER BY ... LIMIT N on unbounded streams by maintaining a sorted buffer of at most K entries. New events that rank within the top-K cause eviction of the worst entry and optional rank-change retractions.

Emit Strategies

• OnUpdate: Emit changelog on every state change (lowest latency)
• OnWatermark: Buffer changes, emit on watermark advance
• Periodic(interval): Emit on timer interval

Ring 0 Constraints

• entries pre-allocated to capacity K — no reallocation during process()
• Sort keys use Vec<u8> memcomparable encoding for zero-branch comparison
• Sorted Vec with binary search: O(log K) search + O(K) shift

Structs

StreamingTopKOperator

Streaming top-K operator for ORDER BY ... LIMIT N.

TopKSortColumn

Configuration for a sort column in the top-K operator.

Enums

TopKEmitStrategy

Emit strategy for the streaming top-K operator.

Functions

encode_f64

Encodes an f64 value as memcomparable bytes.

encode_i64

Encodes an i64 value as memcomparable bytes.

encode_not_null

Encodes a non-null value marker into the sort key.

encode_null

Encodes a null value marker into the sort key.

encode_utf8

Encodes a UTF-8 string as memcomparable bytes.