microvector 0.1.0

Lightweight local vector database with persistence to disk, supporting multiple similarity metrics and easy-to-use API.

microvector

Lightweight local vector database with persistence to disk, supporting multiple similarity metrics and an easy-to-use API.

A refactor and repackaging of HyperDB optimized for CPU-only environments with improved type safety and developer experience.

Features

• 🚀 Simple API: Clean, intuitive interface with just two main methods: save() and search()
• 💾 Persistent Storage: Automatically caches vector stores to .pickle.gz files
• 🔍 Multiple Similarity Metrics: Choose from cosine, dot product, Euclidean, or Derrida distance
• 🎯 Type Safe: Full type annotations with strict pyright compliance
• ⚡ CPU Optimized: Designed for CPU-only environments (no CUDA required)
• 🔄 Flexible Caching: Use persistent stores or create temporary in-memory collections
• 📦 Easy Installation: One-command setup with automatic PyTorch CPU configuration

Installation

pip install microvector

Or for development:

git clone https://github.com/loganpowell/microvector.git
cd microvector
uv sync

Quick Start

from microvector import Client

# Initialize the client
client = Client()

# Save a collection with automatic persistence
client.save(
    partition_name="my_documents",
    collection=[
        {"text": "Python is a popular programming language", "category": "tech"},
        {"text": "Machine learning models learn from data", "category": "ai"},
        {"text": "The quick brown fox jumps over the lazy dog", "category": "example"},
    ]
)

# Search the persisted collection
results = client.search(
    term="artificial intelligence and ML",
    partition_name="my_documents",
    key="text",
    top_k=5
)

for result in results:
    print(f"Score: {result['similarity_score']:.4f} - {result['text']}")

API Reference

Client

The main interface for all vector operations.

Client(
    cache_models: str = "./.cached_models",
    cache_vectors: str = "./.vector_cache",
    embedding_model: str = "infgrad/stella-base-en-v2"
)

Parameters:

• cache_models: Directory for caching downloaded embedding models
• cache_vectors: Directory for persisting vector stores
• embedding_model: HuggingFace model name for generating embeddings

save()

Save a collection to a persistent vector store.

client.save(
    partition_name: str,
    collection: list[dict[str, Any]],
    key: str = "text",
    algo: str = "cosine"
) -> dict[str, Any]

Parameters:

• partition_name: Unique identifier for this vector store
• collection: List of documents (dictionaries) to vectorize
• key: Field name to use for embedding (default: "text")
• algo: Similarity metric - "cosine", "dot", "euclidean", or "derrida"

Returns:

{
    "status": "success",
    "partition": "my_documents",
    "documents_saved": 42,
    "key": "text",
    "algorithm": "cosine"
}

Example:

result = client.save(
    partition_name="products",
    collection=[
        {"description": "Wireless headphones", "price": 99.99},
        {"description": "Smart watch", "price": 299.99},
    ],
    key="description",
    algo="cosine"
)

search()

Search a vector store with semantic similarity.

client.search(
    term: str,
    partition_name: str,
    key: str = "text",
    top_k: int = 5,
    collection: Optional[list[dict[str, Any]]] = None,
    cache: bool = True,
    algo: str = "cosine"
) -> list[dict[str, Any]]

Parameters:

• term: Search query string
• partition_name: Name of the vector store to query
• key: Field name that was used for embedding
• top_k: Maximum number of results to return
• collection: Optional temporary collection (for non-persistent search)
• cache: If True, persist the collection; if False, keep in-memory only
• algo: Similarity metric to use

Returns: List of documents with similarity scores

[
    {
        "text": "Machine learning is awesome",
        "category": "ai",
        "similarity_score": 0.923
    },
    ...
]

Example - Search existing store:

results = client.search(
    term="laptop computers",
    partition_name="products",
    key="description",
    top_k=3
)

Example - Temporary search (no persistence):

results = client.search(
    term="budget phones",
    partition_name="temp_search",
    key="description",
    top_k=5,
    collection=[
        {"description": "iPhone 15 Pro", "price": 999},
        {"description": "Samsung Galaxy S24", "price": 899},
    ],
    cache=False  # Don't save to disk
)

Similarity Algorithms

Algorithm	Best For	Range
cosine	General text similarity (default)	0-1 (higher is more similar)
dot	When magnitude matters	Unbounded
euclidean	Spatial distance	0-∞ (lower is more similar)
derrida	Experimental alternative distance	0-∞ (lower is more similar)

Advanced Usage

Custom Embedding Models

Use any HuggingFace sentence-transformer model:

client = Client(
    embedding_model="sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2"
)

Nested Key Paths

Access nested fields using dot notation:

collection = [
    {
        "product": {
            "name": "Laptop",
            "specs": {"cpu": "Intel i7"}
        }
    }
]

client.save(
    partition_name="products",
    collection=collection,
    key="product.name"
)

Working with Multiple Partitions

Organize different datasets in separate partitions:

# Save different content types
client.save("news_articles", news_data, key="content")
client.save("product_reviews", review_data, key="review_text")
client.save("support_tickets", tickets, key="description")

# Search each independently
news_results = client.search("economy", "news_articles", key="content")
review_results = client.search("quality", "product_reviews", key="review_text")

Development Setup

This project uses uv for dependency management and automatically configures CPU-only PyTorch.

Quick Start

1. Install dependencies:

   uv sync
   

2. Verify setup:

   uv run python setup_dev.py
   

3. Run tests:

   uv run pytest
   

4. Type checking:

   uv run pyright
   

What Gets Installed

• PyTorch (CPU-only): Automatically from PyTorch CPU index
• Transformers: HuggingFace transformers library
• Sentence Transformers: For embedding generation
• NumPy: Numerical computing

No special flags or manual PyTorch installation needed - just uv sync and go!

Performance Tips

1. Reuse Client instances - Model loading is expensive
2. Use persistent caching - Vector computation is cached automatically
3. Batch your saves - Save collections together when possible
4. Choose the right algorithm - Cosine is fastest for most use cases
5. Adjust top_k - Lower values are faster

Architecture

microvector/
├── main.py          # Client API
├── store.py         # Vector storage and similarity search
├── cache.py         # Persistence layer
├── embed.py         # Embedding generation
├── algos.py         # Similarity algorithms
└── utils.py         # Helper functions

License

MIT License - see LICENSE file for details.

Credits

Based on HyperDB by John Dagdelen. Refactored and maintained by Logan Powell.