Substrate & Views

A Substrate is a pluggable storage backend. It provides transactional views for reading and writing chunks.

View Pattern

All storage access goes through views:

SubstrateView — read-only, supports key lookup and prefix scanning
SubstrateMutableView — extends SubstrateView with write staging and atomic commit (to underlying storage)

# Read-only view (context manager)
with storage.new_view() as view:
    # Check if chunk exists, without actually reading it back.
    exists = view.chunk_exists("animals", "cat")

    cat_chunk = view.read_chunk("animals", "cat")

# Mutable view (auto-commits on clean exit, rollback on exception)
with storage.new_mutable_view() as view:
    view.write_chunk(sparkle, code=some_code, note="my note")

    # commits automatically

Storage Backends

InMemory

Volatile, in-process storage. All data lost on exit. Best for testing and ephemeral caches.

storage = memory.InMemory(hv.MODEL_64K_8BIT, "my_store")

Embedded

Persistent, single-machine storage backed by an embedded key-value store. Suitable for local development and moderate-scale deployments.

storage = memory.Embedded(hv.MODEL_64K_8BIT, "/path/to/store")

ScyllaDB (Distributed)

Distributed storage via Cassandra-compatible ScyllaDB. For high-scale, multi-node deployments.

# Not exposed yet...

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