Storage Backends

PRX-Memory supports multiple storage backends for persisting memories and their vector embeddings. The prx-memory-storage crate provides a unified interface that all backends implement.

Available Backends

Backend	Config Value	Vector Support	Persistence	Best For
JSON	json	Embedded in entries	File-based	Development, small datasets
SQLite	sqlite	Built-in vector columns	File-based	Production, medium datasets
LanceDB	lancedb	Native vector index	Directory-based	Large datasets, fast ANN search

Default Backend

The default backend is JSON (PRX_MEMORY_BACKEND=json), which requires no additional setup. For production deployments, SQLite is recommended.

JSON Backend

The simplest backend stores all memories in a single JSON file. It is ideal for development, testing, and small memory sets (under 10,000 entries).

PRX_MEMORY_BACKEND=json
PRX_MEMORY_DB=./data/memory-db.json

Advantages:

• Zero setup -- just specify a file path.
• Human-readable -- inspect and edit with any text editor.
• Portable -- copy the file to move your entire memory database.

Limitations:

• Entire file is loaded into memory on startup.
• Write operations rewrite the full file.
• No indexed vector search -- brute-force scan for similarity.

SQLite Backend

SQLite provides ACID transactions, indexed queries, and built-in vector column support for efficient similarity search.

PRX_MEMORY_BACKEND=sqlite
PRX_MEMORY_DB=./data/memory.db

See SQLite Storage for detailed configuration.

LanceDB Backend (Optional)

LanceDB provides native approximate nearest neighbor (ANN) vector search with columnar storage. Enable it with the lancedb-backend feature flag:

cargo build --release -p prx-memory-mcp --bin prx-memoryd --features lancedb-backend

PRX_MEMORY_BACKEND=lancedb
PRX_MEMORY_DB=./data/lancedb

Feature Flag Required

LanceDB support is not included in the default build. You must enable the lancedb-backend feature flag at compile time.

Choosing a Backend

Scenario	Recommended Backend
Local development	JSON
Production with <100k entries	SQLite
Production with >100k entries	LanceDB
Need human-readable storage	JSON
Need ACID transactions	SQLite
Need fast ANN vector search	LanceDB

Storage Operations

PRX-Memory provides tools for storage maintenance:

Tool	Description
memory_export	Export all memories to a portable format
memory_import	Import memories from an export
memory_migrate	Migrate between storage backends
memory_compact	Optimize storage and reclaim space
memory_reembed	Re-embed all memories with a new model

Next Steps

• SQLite Storage -- SQLite configuration and tuning
• Vector Search -- How vector similarity search works
• Configuration Reference -- All environment variables