Module lag_lead 

LAG/LEAD Operator

Per-row analytic window functions for streaming event processing.

Streaming Semantics

• LAG(col, offset, default): Look back offset events in the partition’s history buffer. Emit immediately since history is always available.
• LEAD(col, offset, default): Buffer current event and wait for offset future events in the partition. Flush remaining with defaults on watermark.

Memory Bounds

Memory is O(P * max(lag_offset, lead_offset)) where P = distinct partitions. A max_partitions limit prevents unbounded partition growth.

Structs

LagLeadConfig

Configuration for a LAG/LEAD operator.

LagLeadFunctionSpec

Specification for a single analytic function (LAG, LEAD, FIRST_VALUE, etc.).

LagLeadMetrics

Metrics for LAG/LEAD operator.

LagLeadOperator

LAG/LEAD streaming operator.

Enums

AnalyticFunctionKind

The kind of analytic window function.