Module large_event 

Large event fragment reassembly for MongoDB change streams.

MongoDB ≥ 6.0.9 supports the $changeStreamSplitLargeEvent pipeline stage, which splits change events exceeding the 16 MiB BSON limit into ordered fragments. Each fragment carries:

• splitEvent.fragment: 1-based ordinal of this fragment
• splitEvent.of: total number of fragments

This module buffers fragments by their resume token prefix and reassembles them into a single event once all fragments arrive.

Error Handling

If fragments arrive out of order or are incomplete after the configured timeout, LargeEventReassemblyFailed is emitted.

Structs

EventFragment

A single fragment of a large change event.

LargeEventReassembler

Buffers and reassembles split large change events.

SplitEventInfo

Metadata about a split event fragment.

Enums

LargeEventError

Error when large event reassembly fails.