Partitioning and Shards

Partitioning and Shards

The compact-CSR partition path is separate from GraphBrew's canonical kernel and reordering experiments. It provides deterministic ownership, ghost metadata, runtime-traffic accounting, and the versioned graph.shard.v1 package.

Build and smoke test

make bfs_p graph_shard_export
./bench/bin/bfs_p -f scripts/test/data/tiny.el -s \
  -n 1 -r 0 -v -P 4 -B total
make check-partition

-P selects the shard count. -B accepts vertices, out, or total.

Export a package

./bench/bin/graph_shard_export \
  -f /path/to/graph.sg \
  -P 16 -B total \
  -E /path/to/output-package

graph.shard.v1 contains a manifest, source/internal mapping sidecars, and per-shard little-endian CSR/ghost arrays. The streamed exporter builds and writes one shard at a time instead of materializing every shard concurrently.

Required invariants

Partition changes must preserve:

• deterministic fingerprints across supported thread counts;
• exact source-ID mappings;
• ownership and ghost coverage;
• valid compact CSR offsets and local slots;
• byte-identical streamed and in-memory package output;
• complete runtime-traffic and capacity accounting.

make check-partition is the authoritative integration gate for these contracts. Partition experiments and evidence are not part of the primary kernel-speedup evaluation unless explicitly selected.