RFC-001: Symbol Sharding for Quote Fan-Out

Not financial advice. Verify claims independently.

Open for comment: the partitioning scheme behind 1M+ concurrent subscribers.

Status: Open for comment · RFC: 001 · Component: fan-out layer

Proposal: partition the outbound channel space by ticker symbol, with hot symbols (top ~20 by subscriber count) getting dedicated shards and the tail sharing a hash partition.

Motivation: during a Micron-scale earnings event, a single symbol generates 40%+ of outbound volume. Unsharded, that volume delays every other symbol's delivery. Sharded, MU's burst is isolated to its own lane.

Open questions for comment:

Shard rebalancing: dynamic (watch subscriber counts) vs. static (pre-assigned)?
Cross-shard ordering: do subscribers need causal ordering across symbols, or is per-symbol ordering sufficient?

Reference implementation: Stock Picks's quote layer. Comments open on the repo.