semantica/docs/reference/vector_store.md

title, description, icon

title	description	icon
Vector Store Module	Unified interface for FAISS, Pinecone, Weaviate, Qdrant, Milvus, and PgVector with hybrid search.	database

semantica.vector_store provides a unified API for storing and searching vector embeddings across all major backends. Swap backends with a one-line change — no application code changes needed.

Exported Classes

Class	Role
VectorStore	Unified interface: store_vectors, search_vectors, update_vectors, delete_vectors
HybridSearch	Fuses dense vector similarity with metadata filtering via RRF or weighted average
MetadataFilter	Chainable filter builder: .eq("type", "person").gt("year", 2020).in_list("tag", [...])
NamespaceManager	Multi-tenant isolation — separate index namespaces per project or user
FAISSStore	Local disk or in-memory — flat, ivf, hnsw, and pq index types
WeaviateStore	Cloud or self-hosted, schema-aware
QdrantStore	Cloud or self-hosted with payload-based filtering
PineconeStore	Managed cloud vector database with serverless and pod modes
MilvusStore	Scalable self-hosted vector database
PgVectorStore	PostgreSQL with pgvector extension — no extra infrastructure
MetadataStore	Standalone metadata indexing and querying
SearchRanker	RRF and weighted-average result fusion

What You Get

Unified interface across FAISS, Pinecone, Weaviate, Qdrant, Milvus, and PgVector. Combine dense vector similarity with metadata filtering and configurable fusion strategies. Rich metadata indexing — query by field values, update fields without re-embedding. Multi-tenant namespace isolation — structural separation, not just metadata filters. Bulk add, delete, and metadata updates — parallel embedding with configurable workers. flat, ivf, hnsw, and pq index types with full configuration control.

Getting Started

VectorStore is the main entry point. Use "inmemory" for development and "faiss" for local production:

from semantica.vector_store import VectorStore

# In-memory (development / testing — no persistence)
store = VectorStore(backend="inmemory", dimension=384)

# FAISS (local, persists to disk via save/load)
store = VectorStore(backend="faiss", dimension=384)

# Add plain text documents (auto-embedded)
ids = store.add_documents(
    documents=["Apple was founded by Steve Jobs.", "Microsoft was co-founded by Bill Gates."],
    metadata=[{"source": "wiki"}, {"source": "wiki"}]
)

# Search by text query (auto-embedded)
results = store.search("technology company founders", limit=5)
for r in results:
    print(f"{r['id']} — score: {r['score']:.3f}")

Quick Start

```python from semantica.vector_store import VectorStore

# In-memory (development)
store = VectorStore(backend="inmemory", dimension=384)

# FAISS (local production)
store = VectorStore(backend="faiss", dimension=384)
```

```python # Add text documents (auto-embedded in batches) ids = store.add_documents( documents=["text one", "text two"], metadata=[{"title": "Document 1"}, {"title": "Document 2"}] )

# Add pre-computed vectors directly
ids = store.store_vectors(
    vectors=[embedding1, embedding2],
    metadata=[{"title": "Document 1"}, {"title": "Document 2"}]
)
```

```python # Search by text query (auto-embeds the query) results = store.search("machine learning", limit=10)

# Search by pre-computed vector
results = store.search_vectors(query_vector, k=10)

for r in results:
    print(f"{r['id']} — score: {r['score']:.3f}")
```

```python from semantica.vector_store import HybridSearch, MetadataFilter

mf = MetadataFilter().eq("category", "research").gt("year", 2022)

# Pass vector_store to the constructor — search() resolves vectors automatically
search  = HybridSearch(vector_store=store)
results = search.search(query=query_vector, k=10, metadata_filter=mf)
```

Backends

# In-memory — no persistence, for development and testing
store = VectorStore(backend="inmemory", dimension=384)

# FAISS — local disk persistence via save() / load()
store = VectorStore(backend="faiss", dimension=384)
store.save("./my_store")   # save to directory
store.load("./my_store")   # restore from directory

No installation or API key required. FAISS requires pip install faiss-cpu.

pip install "semantica[pinecone]"

import os
store = VectorStore(
    backend="pinecone",
    dimension=768,
    api_key=os.getenv("PINECONE_API_KEY"),
    index_name="semantica-index",
    environment="us-east-1-aws"
)

pip install "semantica[weaviate]"

store = VectorStore(
    backend="weaviate",
    dimension=768,
    url="http://localhost:8080",
    class_name="Document"
)

pip install "semantica[qdrant]"

store = VectorStore(
    backend="qdrant",
    dimension=768,
    url="http://localhost:6333",
    collection_name="semantica"
)

pip install "semantica[pgvector]"

store = VectorStore(
    backend="pgvector",
    dimension=768,
    connection_string="postgresql://user:pass@localhost/db",
    table_name="embeddings"
)

connection_string is required — the store raises ValueError at construction if it is absent.

pip install pymilvus

store = VectorStore(
    backend="milvus",
    dimension=768,
    host="localhost",
    port=19530,
    collection_name="semantica"
)

Backend Selection Guide

Backend	Deployment	API Key	Persistence	Best For
inmemory	Process	No	No	Development, unit tests
faiss	Local	No	Via save()/load()	On-premise, offline production
pinecone	Cloud	Yes	Managed	Managed cloud, serverless
weaviate	Self-hosted / Cloud	Optional	Managed	Rich metadata filtering
qdrant	Self-hosted / Cloud	Optional	Managed	High-performance filtering
milvus	Self-hosted	No	Managed	Large-scale production
pgvector	PostgreSQL	No	Managed	Postgres-native integration

HybridSearch

HybridSearch combines vector similarity with metadata filtering. Pass vector_store at construction to avoid supplying raw vectors on every call:

from semantica.vector_store import HybridSearch, MetadataFilter

# With vector_store — search() pulls vectors from the store automatically
search = HybridSearch(vector_store=store)
mf     = MetadataFilter().eq("category", "research").gt("year", 2022)

results = search.search(
    query=query_vector,   # np.ndarray or query string (auto-embedded)
    k=10,
    metadata_filter=mf
)

for r in results:
    print(f"{r['id']} — score: {r['score']:.3f}  metadata: {r['metadata']}")

Without a vector_store, pass vectors explicitly:

search = HybridSearch()
results = search.search(
    query=query_vector,
    vectors=my_vectors,
    metadata=my_metadata,
    vector_ids=my_ids,
    k=10,
    metadata_filter=mf,
)

Multi-source fusion across separate collections:

sources = [
    {"vectors": v1, "metadata": m1, "ids": ids1},
    {"vectors": v2, "metadata": m2, "ids": ids2},
]
fused = search.multi_source_search(query_vector, sources, k=10)

Metadata Filtering

MetadataFilter supports chained conditions — all conditions are ANDed:

from semantica.vector_store import MetadataFilter

mf = MetadataFilter().eq("author", "John Smith")          # equality
mf = MetadataFilter().ne("status", "archived")            # not equal
mf = MetadataFilter().gt("year", 2022).lte("year", 2024)  # range
mf = MetadataFilter().in_list("tag", ["ai", "ml"])        # set membership
mf = MetadataFilter().contains("title", "neural")         # substring / list contains

# Multiple conditions — all must match (AND)
mf = (
    MetadataFilter()
    .eq("category", "research")
    .gt("year", 2022)
    .contains("title", "language model")
)

MetadataFilter Methods

Method	Operator	Description
.eq(field, value)	==	Exact equality
.ne(field, value)	!=	Not equal
.gt(field, value)	>	Greater than
.gte(field, value)	>=	Greater than or equal
.lt(field, value)	<	Less than
.lte(field, value)	<=	Less than or equal
.in_list(field, values)	in	Field value is in list
.contains(field, value)	substring	String contains or list contains

SearchRanker

SearchRanker fuses results from multiple ranked lists:

from semantica.vector_store import SearchRanker

# Reciprocal Rank Fusion — robust to score scale differences
ranker  = SearchRanker(strategy="reciprocal_rank_fusion")
fused   = ranker.rank([results_list_1, results_list_2])

# Weighted average — requires normalised scores on the same scale
ranker  = SearchRanker(strategy="weighted_average")
fused   = ranker.rank([results_list_1, results_list_2], weights=[0.7, 0.3])

Fusion strategy	Description
reciprocal_rank_fusion	Rank-based combination via RRF — robust to score scale differences (default)
weighted_average	Weighted sum of scores — pass weights=[...] to rank()

Namespace Isolation

Use NamespaceManager to assign vectors to named namespaces for multi-tenant isolation:

from semantica.vector_store import NamespaceManager, VectorStore

store      = VectorStore(backend="inmemory", dimension=384)
ns_manager = NamespaceManager()

ns_manager.create_namespace("tenant_a", description="Customer A data")
ns_manager.create_namespace("tenant_b", description="Customer B data")

# Store vectors, then assign them to a namespace
ids_a = store.store_vectors(embeddings_a, metadata=metadata_a)
for vid in ids_a:
    ns_manager.add_vector_to_namespace(vid, "tenant_a")

# List all namespace names
for name in ns_manager.list_namespaces():     # returns List[str]
    print(name)

# Get all vectors in a namespace
vectors_in_a = ns_manager.get_namespace_vectors("tenant_a")

# Look up which namespace a vector belongs to
ns = ns_manager.get_vector_namespace("vec_0")

ns_manager.delete_namespace("tenant_a")

Batch Operations

# Batch add text documents — parallel embedding with configurable workers
ids = store.add_documents(
    documents=large_doc_list,
    metadata=large_meta_list,
    batch_size=32,     # texts per embedding batch
    parallel=True,     # use ThreadPoolExecutor
)

# Batch add pre-computed vectors
ids = store.store_vectors(vectors=embeddings_list, metadata=meta_list)

# Delete by vector ID list
store.delete_vectors(vector_ids=["vec_0", "vec_1", "vec_2"])

# Update vectors in-place (rebuilds index for inmemory backend)
store.update_vectors(
    vector_ids=["vec_0"],
    new_vectors=[new_embedding]
)

Persistence (FAISS and in-memory)

store = VectorStore(backend="faiss", dimension=384)
store.add_documents(documents=docs, metadata=meta)

# Save to a directory — creates index.bin and store_data.pkl
store.save("./vector_store_backup")

# Restore in a new process
store2 = VectorStore(backend="faiss", dimension=384)
store2.load("./vector_store_backup")

Cloud backends (Pinecone, Weaviate, Qdrant, Milvus, PgVector) manage persistence themselves. `save()`/`load()` are for the in-memory and FAISS backends only.

MetadataStore

MetadataStore indexes structured metadata and lets you query by field values without a vector:

from semantica.vector_store import MetadataStore

meta_store = MetadataStore()

# Store and retrieve metadata
meta_store.store_metadata("doc1", {"author": "Alice", "year": 2024, "category": "research"})
meta_store.store_metadata("doc2", {"author": "Bob",   "year": 2023, "category": "review"})

# Query — returns List[str] of matching vector IDs
ids = meta_store.query_metadata({"category": "research", "year": 2024})

# OR query
ids = meta_store.query_metadata({"category": "research"}, operator="OR")

# Get and update metadata for a specific vector
meta = meta_store.get_metadata("doc1")
meta_store.update_metadata("doc1", {"score": 0.92})

# Get all unique values for a field
years = meta_store.get_field_values("year")

# Statistics
stats = meta_store.get_stats()
# {"total_vectors": 2, "indexed_fields": 3, "field_counts": {...}}

FAISS Index Type Reference

FAISS index type is configured by creating a FAISSStore directly and calling create_index(). Use lowercase type names:

from semantica.vector_store import FAISSStore

store = FAISSStore(dimension=384)

# flat — brute-force exact search
store.create_index(index_type="flat", metric="L2")

# ivf — inverted file index
store.create_index(index_type="ivf", metric="L2", nlist=100)

# hnsw — hierarchical navigable small world graph
store.create_index(index_type="hnsw", metric="L2", M=32)

# pq — product quantization for memory efficiency
store.create_index(index_type="pq", metric="L2", m=8)

Index	Memory	Speed	Accuracy	When to Use
flat	High	Slow	Exact (100%)	< 100K vectors, correctness critical
ivf	Medium	Fast	~95–98%	100K–10M vectors, good balance
hnsw	Medium-High	Very fast	~97–99%	Low latency, production retrieval
pq	Low	Fast	~90–95%	Millions of vectors, memory-constrained

When using `VectorStore(backend="faiss")`, the underlying `FAISSStore` is initialised with a flat index by default. To use ivf/hnsw/pq, construct `FAISSStore` directly and call `create_index()` with the desired type.

Common Workflows

```python from semantica.vector_store import VectorStore

store = VectorStore(backend="faiss", dimension=384)

# Index documents
store.add_documents(
    documents=corpus_texts,
    metadata=[{"source": src} for src in sources],
    batch_size=64,
)

# Persist
store.save("./corpus_index")

# Query
results = store.search("What is knowledge graph construction?", limit=5)
for r in results:
    print(f"[{r['score']:.3f}] {r['metadata']['source']}")
```

```python from semantica.vector_store import VectorStore, HybridSearch, MetadataFilter

store  = VectorStore(backend="inmemory", dimension=384)
search = HybridSearch(vector_store=store)

# Only return results from 2023+ with category "research"
mf = MetadataFilter().gte("year", 2023).eq("category", "research")
results = search.search(query=query_vector, k=10, metadata_filter=mf)
```

```python from semantica.vector_store import HybridSearch, SearchRanker

search = HybridSearch()
sources = [
    {"vectors": v1, "metadata": m1, "ids": ids1},
    {"vectors": v2, "metadata": m2, "ids": ids2},
]
fused = search.multi_source_search(query_vector, sources, k=10)

# Custom fusion weights
ranker = SearchRanker(strategy="weighted_average")
fused  = ranker.rank([results_a, results_b], weights=[0.7, 0.3])
```

```python from semantica.vector_store import VectorStore, NamespaceManager

store = VectorStore(backend="inmemory", dimension=384)
ns    = NamespaceManager()

ns.create_namespace("project_a")
ns.create_namespace("project_b")

ids = store.add_documents(docs_a, metadata=meta_a)
for vid in ids:
    ns.add_vector_to_namespace(vid, "project_a")

# Check ownership
print(ns.get_vector_namespace(ids[0]))  # "project_a"
print(ns.get_namespace_stats("project_a"))
```

Tips and Common Pitfalls

**Match vector dimension to your embedding model.** The `dimension` parameter must exactly match your embedding model's output size — `BAAI/bge-small-en-v1.5` = 384, `all-MiniLM-L6-v2` = 384, `all-mpnet-base-v2` = 768, `bge-large-en-v1.5` = 1024. A mismatch raises an error at insert time. **FAISS index type names are lowercase.** The `FAISSStore.create_index()` method expects `"flat"`, `"ivf"`, `"hnsw"`, `"pq"` — not `"Flat"`, `"IVF"`, `"HNSW"`, `"PQ"`. Uppercase values raise `ValidationError`. **inmemory and faiss backends lose data on process exit without `save()`.** Call `store.save(path)` after adding vectors. Cloud backends (Pinecone, Qdrant, Weaviate, Milvus, PgVector) persist automatically. **Use `HybridSearch(vector_store=store)` to avoid passing raw vectors on every call.** When `vector_store` is set, `search()` pulls vectors and metadata from the store automatically — you only need to pass the query and filter. **Use `add_documents()` for text, `store_vectors()` for pre-computed embeddings.** `add_documents()` auto-embeds in parallel batches. If your embeddings are already computed (e.g. from a fine-tuned model), use `store_vectors()` directly to skip re-embedding. **Use `NamespaceManager` for multi-tenant applications.** Storing all tenants' vectors in the same collection and filtering by metadata at query time is slow and risks data leakage if a filter is accidentally omitted. Namespace isolation is both faster (smaller search space) and safer (structural isolation). **Update metadata without re-embedding.** `MetadataStore.update_metadata(id, {...})` changes attached fields (status, tags, review date) without re-running the embedding model. Use this for state changes that don't affect semantic content. Generate the vectors stored here. AgentContext uses VectorStore for memory retrieval. Chunk documents before embedding and storing. Ingest documents before embedding and storing.