Vector Search Guide

This guide covers comprehensive vector search and indexing capabilities in the MatrixOne Python SDK, including modern vector operations for AI applications.

Important

⭐ Production Critical: If you’re using IVF indexes in production, jump directly to IVF Index Health Monitoring to learn how to monitor and maintain index quality with get_ivf_stats(). This is essential for optimal vector search performance.

Overview

MatrixOne provides powerful vector operations designed for modern AI and machine learning applications:

• Modern Vector API: High-level vector operations with vector_ops and vector_query managers

• Multiple Index Types: HNSW and IVF indexes for different performance characteristics

• ⭐ Index Health Monitoring: get_ivf_stats() for monitoring IVF index balance and performance

• Flexible Data Types: Support for vecf32 and vecf64 vector types with configurable dimensions

• Distance Metrics: L2, cosine, inner product, and negative inner product calculations

• Client Integration: Seamless integration with MatrixOne client interface

• ORM Support: Full SQLAlchemy integration with vector types

• Performance Optimization: Built-in query optimization and index management

The vector guide covers both basic vector operations and advanced indexing features.

Modern Vector Operations

The MatrixOne Python SDK provides a modern, high-level API for vector operations that simplifies common AI workflows.

Creating Vector Tables with Table Models

from matrixone import Client
from sqlalchemy import Column, Integer, String, Text
from matrixone.orm import declarative_base
from matrixone.sqlalchemy_ext import create_vector_column

# Create client and connect (see configuration_guide for connection options)
client = Client()
client.connect(host="127.0.0.1", port=6001, user="root", password="111", database="test")

# Define table models
Base = declarative_base()

class Document(Base):
    __tablename__ = 'documents'
    id = Column(Integer, primary_key=True)
    title = Column(String(200))
    content = Column(Text)
    category = Column(String(50))
    # Use create_vector_column for ORM with distance methods (l2_distance, cosine_distance, etc.)
    embedding = create_vector_column(384, precision='f32')

class Product(Base):
    __tablename__ = 'products'
    id = Column(Integer, primary_key=True)
    name = Column(String(200))
    description = Column(Text)
    category = Column(String(50))
    # Use create_vector_column for ORM with distance methods
    features = create_vector_column(512, precision='f64')

# Create tables using models
client.create_table(Document)
client.create_table(Product)

# Alternative: Create tables using create_table API with column definitions
client.create_table("documents_alt", {
    "id": "int",
    "title": "varchar(200)",
    "content": "text",
    "category": "varchar(50)",
    "embedding": "vecf32(384)"  # 384-dimensional f32 vector
}, primary_key="id")

Vector Index Management

MatrixOne provides powerful vector index management through the vector_ops API:

Important

⚠️ Critical: IVF Index Creation Timing

IVF indexes should be created AFTER inserting initial data:

# ✅ CORRECT ORDER:
# 1. Create table
client.create_table(Document)

# 2. Insert data first (bulk insert recommended)
client.batch_insert(Document, initial_documents)

# 3. Create IVF index last
client.vector_ops.enable_ivf()
client.vector_ops.create_ivf("documents", "idx_embedding", "embedding", lists=50)

# 4. Continue inserting data (IVF supports dynamic updates)
client.insert(Document, new_doc)  # ✅ Works fine with IVF

Why? Creating index after initial data provides better clustering and balance.

Unlike HNSW: IVF supports insert/update/delete after index creation ✅

# Enable IVF indexing
client.vector_ops.enable_ivf()

# Create IVF index for similarity search
client.vector_ops.create_ivf(
    "documents",
    name="idx_embedding_ivf",
    column="embedding",
    lists=50,                    # Number of clusters
    op_type="vector_l2_ops"      # Distance function
)

# Create another IVF index with different parameters
client.vector_ops.create_ivf(
    "products",
    name="idx_features_ivf",
    column="features",
    lists=100,                   # More clusters for larger datasets
    op_type="vector_cosine_ops"  # Cosine distance
)

# Enable HNSW indexing
client.vector_ops.enable_hnsw()

# Create HNSW index
client.vector_ops.create_hnsw(
    "documents",
    name="idx_embedding_hnsw",
    column="embedding",
    m=16,                        # Number of bi-directional links
    ef_construction=200,         # Size of dynamic candidate list
    ef_search=50                 # Size of dynamic candidate list for search
)

# Drop vector indexes using drop method
client.vector_ops.drop("documents", "idx_embedding_ivf")
client.vector_ops.drop("documents", "idx_embedding_hnsw")

IVF LIMIT BY RANK - Fine-Grained Search Control

The IVF LIMIT BY RANK feature provides fine-grained control over vector search execution strategies, allowing you to balance between speed and accuracy.

Three Ranking Modes:

from matrixone.ivf_rank import IVFRankMode, IVFRankOptions

# Mode 1: PRE - Pre-filter mode
# Applies WHERE clause filtering BEFORE vector search
# ⚠️  Requires high selectivity of filter condition
# ❌ Poor performance if filter selectivity is low
# Best for: Highly selective filters (e.g., filtering to <1% of data)
options_pre = IVFRankOptions(mode=IVFRankMode.PRE)

# Mode 2: POST - Post-filter mode (RECOMMENDED)
# Performs vector search FIRST using IVF index, then applies filtering
# ✅ Best performance in most cases
# ✅ Recall typically not affected
# ✅ Use as default unless you have specific reasons for PRE
# Best for: Most production scenarios, optimal performance
options_post = IVFRankOptions(mode=IVFRankMode.POST)

# Mode 3: FORCE - Force mode
# Forces IVF index usage regardless of optimizer decision
# Best for: Debugging, ensuring consistent behavior
options_force = IVFRankOptions(mode=IVFRankMode.FORCE)

Usage in Vector Search:

from matrixone.ivf_rank import IVFRankMode, IVFRankOptions
import numpy as np

# Create IVF index first
client.vector_ops.enable_ivf()
client.vector_ops.create_ivf("documents", "idx_embedding", "embedding", lists=50)

# Search with PRE mode (fast)
query_vector = np.random.rand(384).tolist()
results_fast = client.vector_ops.similarity_search(
    "documents",
    vector_column="embedding",
    query_vector=query_vector,
    limit=10,
    distance_type="cosine",
    rank_mode=IVFRankMode.PRE  # Fast approximate search
)

# Search with POST mode (accurate)
results_accurate = client.vector_ops.similarity_search(
    "documents",
    vector_column="embedding",
    query_vector=query_vector,
    limit=10,
    distance_type="cosine",
    rank_mode=IVFRankMode.POST  # Slower but more accurate
)

Important Considerations:

Warning

⚠️ PRE Mode (Pre-filter):

• Requires HIGH selectivity of the WHERE clause filter

• If filter selectivity is poor (filters out <50% of data), performance degrades significantly

• Only use when you know the filter is highly selective (e.g., filtering to <1% of data)

✅ POST Mode (Post-filter) - RECOMMENDED:

• Best performance in most cases

• Recall is typically not affected

• Use as default for production systems

• Only switch to PRE if you encounter recall issues AND have a highly selective filter

🔧 FORCE Mode:

• Use only for debugging or specific performance testing

• May override optimizer’s better choices

• Can lead to suboptimal query plans

Note

HNSW Index Requirements:

1. Primary Key: Requires BigInteger primary key (not Integer)

2. Creation Workflow:

   # HNSW: Insert ALL data → Create index → Read-only
   client.create_table(Document)
   client.batch_insert(Document, all_data)  # ALL data first
   client.vector_ops.create_hnsw(...)       # Then index
   # Cannot insert more data
   

   🚧 Dynamic updates coming soon. Current workaround: Drop → Modify → Recreate

IVF vs HNSW Quick Comparison:

Feature	IVF	HNSW
Creation Timing	After initial data	After ALL data
Dynamic Updates	✅ Yes	🚧 Coming soon
Primary Key	Any integer type	BigInteger required
Recall	95-98%	>99%
Best For	Dynamic data	Static data

Vector Data Insertion

Insert vector data using the modern insert API:

import numpy as np

# Insert single document
client.insert(Document, {
    "id": 1,
    "title": "AI Research Paper",
    "content": "Advanced artificial intelligence research",
    "category": "research",
    "embedding": np.random.rand(384).astype(np.float32).tolist()
})

# Batch insert multiple documents
documents = [
    {
        "id": 2,
        "title": "Machine Learning Guide",
        "content": "Comprehensive machine learning tutorial",
        "category": "tutorial",
        "embedding": np.random.rand(384).astype(np.float32).tolist()
    },
    {
        "id": 3,
        "title": "Data Science Handbook",
        "content": "Complete data science reference",
        "category": "reference",
        "embedding": np.random.rand(384).astype(np.float32).tolist()
    }
]

client.batch_insert(Document, documents)

Vector Similarity Search

The vector_query API provides powerful similarity search capabilities:

# Perform vector similarity search
query_vector = np.random.rand(384).astype(np.float32).tolist()

# L2 distance search (returns list of tuples)
results = client.vector_ops.similarity_search(
    "documents",
    vector_column="embedding",
    query_vector=query_vector,
    limit=5,
    distance_type="l2"
)

print("L2 Distance Search Results:")
for result in results:
    print(f"  ID: {result[0]}, Title: {result[1]}, Distance: {result[-1]:.4f}")

# Cosine distance search (returns list of tuples)
cosine_results = client.vector_ops.similarity_search(
    "documents",
    vector_column="embedding",
    query_vector=query_vector,
    limit=5,
    distance_type="cosine"
)

print("Cosine Distance Search Results:")
for result in cosine_results:
    print(f"  ID: {result[0]}, Title: {result[1]}, Distance: {result[-1]:.4f}")

Advanced Vector Search

# Search with offset for pagination
results = client.vector_ops.similarity_search(
    "documents",
    vector_column="embedding",
    query_vector=query_vector,
    limit=10,
    offset=20,  # Skip first 20 results
    distance_type="l2"
)

# Search with custom select columns
results = client.vector_ops.similarity_search(
    "documents",
    vector_column="embedding",
    query_vector=query_vector,
    limit=5,
    distance_type="l2",
    select_columns=["id", "title", "content"]  # Only return these columns
)

# Search with category filtering
results = client.vector_ops.similarity_search(
    "documents",
    vector_column="embedding",
    query_vector=query_vector,
    limit=5,
    distance_type="l2",
    where_conditions=["category = ?"],
    where_params=["research"]
)

Complex Vector Queries with Query Builder

For complex vector queries, use the query builder with vector functions:

 # Complex vector query with JOIN
# ORM-style query with JOIN and vector filtering using client.query
from sqlalchemy import and_

results = client.query(Document).select(
    Document.id,
    Document.title,
    Document.content,
    Document.embedding.l2_distance(query_vector).label('distance')
).join(
    Category, Document.category_id == Category.id
).filter(
    and_(
        Document.embedding.l2_distance(query_vector) < 0.5,
        Category.name == 'AI'
    )
).order_by(
    Document.embedding.l2_distance(query_vector)
).limit(10).all()

# ORM-style subquery for complex vector filtering
from sqlalchemy import select

# Create subquery for similar documents
similar_docs = select(
    Document.id,
    Document.title,
    Document.embedding.l2_distance(query_vector).label('distance')
).where(
    Document.embedding.l2_distance(query_vector) < 0.8
).order_by('distance').limit(20).subquery('similar_docs')

# Join subquery with full document data (use session.query for subquery joins)
results = session.query(
    similar_docs.c.id,
    similar_docs.c.title,
    similar_docs.c.distance,
    Document.content
).join(
    Document, similar_docs.c.id == Document.id
).all()

# ORM-style vector query with aggregation using client.query
from sqlalchemy import func

results = client.query(Document).select(
    Document.category,
    func.count(Document.id).label('doc_count'),
    func.avg(Document.embedding.l2_distance(query_vector)).label('avg_distance')
).filter(
    Document.embedding.l2_distance(query_vector) < 1.0
).group_by(
    Document.category
).having(
    func.count(Document.id) > 5
).all()

 # ORM-style IN subquery for top-k vector results using client.query
 from sqlalchemy import select

 # Create subquery to get top-k similar document IDs
 top_ids = select(Document.id).where(
     Document.embedding.l2_distance(query_vector) < 0.5
 ).order_by(
     Document.embedding.l2_distance(query_vector)
 ).limit(10).scalar_subquery()

 # Query full documents using IN clause
 results = client.query(Document).filter(
     Document.id.in_(top_ids)
 ).all()

Async Vector Operations

import asyncio
from matrixone import AsyncClient

async def async_vector_operations():
    # Get connection parameters
    host, port, user, password, database = get_connection_params()

    client = AsyncClient()
    await client.connect(host=host, port=port, user=user, password=password, database=database)

    # Create vector table using async create_table API
    await client.create_table("async_documents", {
        "id": "int",
        "title": "varchar(200)",
        "embedding": "vecf32(256)"
    }, primary_key="id")

    # Enable IVF indexing
    await client.vector_ops.enable_ivf()

    # Create vector index
    await client.vector_ops.create_ivf(
        "async_documents",
        name="idx_async_embedding",
        column="embedding",
        lists=25,
        op_type="vector_l2_ops"
    )

    # Insert data using async insert API
    await client.insert(AsyncDocument, {
        "id": 1,
        "title": "Async Document",
        "embedding": np.random.rand(256).astype(np.float32).tolist()
    })

    # Vector similarity search using async vector_query API
    query_vector = np.random.rand(256).astype(np.float32).tolist()
    results = await client.vector_ops.similarity_search(
        "async_documents",
        vector_column="embedding",
        query_vector=query_vector,
        limit=3,
        distance_type="l2"
    )

    print("Async Vector Search Results:")
    for result in results.rows:
        print(f"  {result[1]} (Distance: {result[-1]:.4f})")

    # Clean up
    await client.drop_table("async_documents")
    await client.disconnect()

asyncio.run(async_vector_operations())

ORM with Vector Types

from sqlalchemy import Column, Integer, String, Text
from matrixone.orm import declarative_base
from matrixone.sqlalchemy_ext import create_vector_column

# Define ORM models with vector columns
Base = declarative_base()

class Document(Base):
    __tablename__ = 'orm_documents'

    id = Column(Integer, primary_key=True, autoincrement=True)
    title = Column(String(200), nullable=False)
    content = Column(Text)
    category = Column(String(50))
    embedding = create_vector_column(384, "f32")  # 384-dimensional f32 vector

# Create table using ORM model
client.create_table(Document)

# Insert data using client API
client.insert(Document, {
    "title": "ORM Document",
    "content": "This is a document created using ORM",
    "category": "tutorial",
    "embedding": np.random.rand(384).astype(np.float32).tolist()
})

# Query using client API with filtering
documents = client.query(Document).filter(Document.category == "tutorial").all()
for doc in documents:
    print(f"Document: {doc.title}, Category: {doc.category}")

# Clean up
client.drop_table(Document)

Vector Index Types and Performance

MatrixOne supports different vector index types for different use cases:

# IVF Index - Good for large datasets (first argument is positional)
client.vector_ops.create_ivf(
    "large_dataset",  # table name - positional argument
    name="idx_ivf_large",
    column="embedding",
    lists=1000,  # More lists for larger datasets
    op_type="vector_l2_ops"
)

# IVF Index with cosine distance
client.vector_ops.create_ivf(
    "recommendations",  # table name - positional argument
    name="idx_ivf_cosine",
    column="features",
    lists=100,
    op_type="vector_cosine_ops"
)

# IVF Index with inner product
client.vector_ops.create_ivf(
    "similarity",  # table name - positional argument
    name="idx_ivf_inner",
    column="vectors",
    lists=50,
    op_type="vector_inner_product_ops"
)

Vector Data Management

from sqlalchemy import func

# Update vector data using client.query
doc = client.query(Document).filter(Document.id == 1).first()
if doc:
    doc.embedding = new_embedding_vector
    # Note: Changes are automatically committed with client.query

# Or use bulk update
client.query(Document).filter(Document.id == 1).update(
    {Document.embedding: new_embedding_vector}
)

# Delete vector data using client.query
client.query(Document).filter(Document.id == 1).delete()

# Query vector data with conditions
results = client.query(Document).filter(Document.id > 5).all()
for doc in results:
    print(f"Document: {doc.title}")

# Get vector statistics using client.query
total_docs = client.query(Document).select(
    func.count(Document.id)
).scalar()
print(f"Total documents: {total_docs}")

Performance Optimization

# Batch operations for better performance
large_batch = []
for i in range(1000):
    large_batch.append({
        "id": i,
        "title": f"Document {i}",
        "embedding": np.random.rand(384).astype(np.float32).tolist()
    })

# Use batch_insert for large datasets
client.batch_insert(Document, large_batch)

# Optimize index parameters for your use case
client.vector_ops.create_ivf(
    "documents",
    name="idx_optimized",
    column="embedding",
    lists=200,  # Adjust based on dataset size
    op_type="vector_l2_ops"
)

# Use appropriate distance functions
# - L2: Good for general similarity
# - Cosine: Good for normalized vectors
# - Inner Product: Good for specific similarity measures

Error Handling

from matrixone.exceptions import QueryError, ConnectionError

def robust_vector_operations():
    try:
        # Create vector table with error handling
        try:
            client.create_table("robust_docs", {
                "id": "int",
                "embedding": "vecf32(128)"
            }, primary_key="id")
        except QueryError as e:
            print(f"Table creation failed: {e}")

        # Create index with error handling
        try:
            client.vector_ops.create_ivf(
                "robust_docs",
                name="idx_robust",
                column="embedding",
                lists=10,
                op_type="vector_l2_ops"
            )
        except QueryError as e:
            print(f"Index creation failed: {e}")

        # Insert data with error handling
        try:
            client.insert(RobustDocument, {
                "id": 1,
                "embedding": [0.1] * 128
            })
        except QueryError as e:
            print(f"Data insertion failed: {e}")

        # Vector search with error handling
        try:
            results = client.vector_ops.similarity_search(
                "robust_docs",
                vector_column="embedding",
                query_vector=[0.1] * 128,
                limit=5,
                distance_type="l2"
            )
            print(f"Search successful: {len(results.rows)} results")
        except QueryError as e:
            print(f"Vector search failed: {e}")

    except ConnectionError as e:
        print(f"Connection failed: {e}")
    finally:
        # Clean up
        try:
            client.drop_table("robust_docs")
        except Exception as e:
            print(f"Cleanup warning: {e}")

robust_vector_operations()

Best Practices

1. Choose the right vector type: - Use vecf32 for memory efficiency - Use vecf64 for higher precision

2. Optimize IVF index parameters:

   Lists Selection: <1K: 10-20 | 1K-100K: 50-200 | >100K: √N to 4×√N

   Balance Ratio: <2.0 ✅ Good | 2.0-2.5 ⚠️ Monitor | >2.5 ❌ Rebuild

   Rebuild When: New data >20%, ratio >2.5, or performance degrades

3. Use batch operations: - Use batch_insert for large datasets (much faster than individual inserts) - Use batch_update for bulk updates - Batch size recommendation: 1000-10000 records per batch

4. Choose appropriate distance functions:

   • L2 (Euclidean): General purpose, geometric similarity

   • Cosine: Normalized vectors, direction-based similarity (text embeddings)

   • Inner Product: When magnitude matters (recommendation systems)

   Note

   Distance Type Options:

   • distance_type="l2" - L2 distance (Euclidean)

   • distance_type="l2_sq" - L2 squared distance (faster, no sqrt)

   • distance_type="cosine" - Cosine distance

   • distance_type="inner_product" - Inner product

   SDK uses correct L2 (not squared) by default. Use l2_sq if you need squared distance.

5. Monitor IVF index health (⭐ Production Critical): - Check index health after bulk data operations - Set up periodic health checks (daily/weekly) - Track metrics over time to identify degradation - Use get_ivf_stats() to monitor balance ratio - Rebuild proactively when balance ratio > 2.5

6. Monitor performance: - Use performance logging - Monitor query execution times - Track slow query thresholds - Optimize based on usage patterns

IVF Index Health Monitoring

⭐ PRODUCTION CRITICAL ⭐

Monitor IVF index health to ensure optimal performance. The get_ivf_stats method is critical for evaluating index quality and determining when to rebuild indexes.

Why IVF Stats Matter:

• Evaluate index balance - unbalanced indexes lead to poor query performance

• Monitor cluster distribution - identify hot spots and load imbalance

• Determine rebuild timing - know when index quality has degraded

• Capacity planning - understand how data distributes across centroids

Basic Usage

from matrixone import Client

client = Client()
client.connect(host="127.0.0.1", port=6001, user="root", password="111", database="test")

# Get IVF index statistics for a table
# Method 1: Specify column name explicitly
stats = client.vector_ops.get_ivf_stats("documents", "embedding")

# Method 2: Auto-infer column name (if only one vector column exists)
stats = client.vector_ops.get_ivf_stats("documents")

# Method 3: Use with ORM model
from matrixone.orm import declarative_base
from sqlalchemy import Column, Integer, String
from matrixone.sqlalchemy_ext import create_vector_column

Base = declarative_base()

class Document(Base):
    __tablename__ = 'documents'
    id = Column(Integer, primary_key=True)
    title = Column(String(200))
    embedding = create_vector_column(384, 'f32')

stats = client.vector_ops.get_ivf_stats(Document, "embedding")

Understanding the Return Value

The get_ivf_stats method returns a comprehensive dictionary with the following structure:

Example Return Value:

{
    'database': 'test',
    'table_name': 'documents',
    'column_name': 'embedding',
    'index_tables': {
        'metadata': '__mo_index_ivf_0012e2e4-0153-7bd7-acf0-1f32def60681',
        'centroids': '__mo_index_ivf_0012e2e4-0153-7bd7-acf0-1f32def60682',
        'entries': '__mo_index_ivf_0012e2e4-0153-7bd7-acf0-1f32def60683'
    },
    'distribution': {
        'centroid_id': [0, 1, 2, 3, 4],
        'centroid_count': [8, 5, 7, 6, 4],
        'centroid_version': [0, 0, 0, 0, 0]
    }
}

Field Descriptions:

• database: Name of the database containing the table

• table_name: Name of the table with the IVF index

• column_name: Name of the vector column being indexed

• index_tables: Internal IVF index table names (metadata, centroids, entries)

• distribution: The most important section for monitoring:

  • centroid_id: List of centroid cluster IDs

  • centroid_count: Number of vectors assigned to each centroid (critical for balance analysis)

  • centroid_version: Version number of each centroid (usually all 0 for stable indexes)

Analyzing Index Balance

Key Metrics to Evaluate:

# Get statistics
stats = client.vector_ops.get_ivf_stats("documents", "embedding")

# Extract distribution data
distribution = stats['distribution']
centroid_ids = distribution['centroid_id']
centroid_counts = distribution['centroid_count']
centroid_versions = distribution['centroid_version']

# Calculate balance metrics
total_centroids = len(centroid_ids)
total_vectors = sum(centroid_counts)
min_count = min(centroid_counts) if centroid_counts else 0
max_count = max(centroid_counts) if centroid_counts else 0
avg_count = total_vectors / total_centroids if total_centroids > 0 else 0

# Balance ratio: ideal is 1.0, higher values indicate imbalance
balance_ratio = max_count / min_count if min_count > 0 else float('inf')

# Standard deviation: measure of distribution spread
import statistics
std_dev = statistics.stdev(centroid_counts) if len(centroid_counts) > 1 else 0

print("=" * 60)
print("IVF INDEX HEALTH REPORT")
print("=" * 60)
print(f"Database: {stats['database']}")
print(f"Table: {stats['table_name']}")
print(f"Column: {stats['column_name']}")
print(f"\nIndex Tables:")
print(f"  - Metadata: {stats['index_tables']['metadata']}")
print(f"  - Centroids: {stats['index_tables']['centroids']}")
print(f"  - Entries: {stats['index_tables']['entries']}")
print(f"\nDistribution Metrics:")
print(f"  - Total Centroids: {total_centroids}")
print(f"  - Total Vectors: {total_vectors}")
print(f"  - Vectors per Centroid (avg): {avg_count:.2f}")
print(f"  - Min Vectors in Centroid: {min_count}")
print(f"  - Max Vectors in Centroid: {max_count}")
print(f"  - Balance Ratio (max/min): {balance_ratio:.2f}")
print(f"  - Standard Deviation: {std_dev:.2f}")
print(f"\nCentroid Details:")
for cid, count, version in zip(centroid_ids, centroid_counts, centroid_versions):
    percentage = (count / total_vectors * 100) if total_vectors > 0 else 0
    bar = "█" * int(count / max_count * 40) if max_count > 0 else ""
    print(f"  Centroid {cid:3d}: {count:5d} vectors ({percentage:5.1f}%) {bar}")
print("=" * 60)

Example Output:

============================================================
IVF INDEX HEALTH REPORT
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Database: test
Table: documents
Column: embedding

Index Tables:
  - Metadata: __mo_index_ivf_0012e2e4-0153-7bd7-acf0-1f32def60681
  - Centroids: __mo_index_ivf_0012e2e4-0153-7bd7-acf0-1f32def60682
  - Entries: __mo_index_ivf_0012e2e4-0153-7bd7-acf0-1f32def60683

Distribution Metrics:
  - Total Centroids: 5
  - Total Vectors: 30
  - Vectors per Centroid (avg): 6.00
  - Min Vectors in Centroid: 4
  - Max Vectors in Centroid: 8
  - Balance Ratio (max/min): 2.00
  - Standard Deviation: 1.58

Centroid Details:
  Centroid   0:     8 vectors ( 26.7%) ████████████████████████████████████████
  Centroid   1:     5 vectors ( 16.7%) █████████████████████████
  Centroid   2:     7 vectors ( 23.3%) ███████████████████████████████████
  Centroid   3:     6 vectors ( 20.0%) ██████████████████████████████
  Centroid   4:     4 vectors ( 13.3%) ████████████████████
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Health Check and Decision Making

Automated Health Checks:

def check_ivf_index_health(client, table_name, column_name):
    """Quick IVF health check - see best_practices.rst for detailed version."""
    stats = client.vector_ops.get_ivf_stats(table_name, column_name)
    counts = stats['distribution']['centroid_count']

    balance_ratio = max(counts) / min(counts) if min(counts) > 0 else float('inf')

    if balance_ratio < 2.0:
        return {'status': 'HEALTHY', 'balance_ratio': balance_ratio}
    elif balance_ratio < 2.5:
        return {'status': 'FAIR', 'balance_ratio': balance_ratio}
    else:
        return {'status': 'CRITICAL', 'balance_ratio': balance_ratio}

# Quick health check
health = check_ivf_index_health(client, "documents", "embedding")
print(f"Status: {health['status']}, Balance: {health['balance_ratio']:.2f}")

When to Rebuild the IVF Index

Rebuild when: Balance ratio >2.5, bulk data changes (>20%), or performance degrades

Rebuild Process:

import math

# Check and rebuild if needed
stats = client.vector_ops.get_ivf_stats("documents", "embedding")
counts = stats['distribution']['centroid_count']
balance_ratio = max(counts) / min(counts) if min(counts) > 0 else float('inf')

if balance_ratio > 2.5:
    # Drop and recreate with optimal lists
    client.vector_ops.drop("documents", "idx_embedding_ivf")

    optimal_lists = int(math.sqrt(sum(counts)) * 2)
    client.vector_ops.create_ivf("documents", "idx_embedding_ivf", "embedding",
                                  lists=optimal_lists, op_type="vector_l2_ops")
    print(f"✅ Index rebuilt with {optimal_lists} lists")

Best Practices for IVF Index Monitoring

• Check health weekly or after bulk operations

• Alert when balance ratio > 2.5

• Rebuild proactively (don’t wait for severe degradation)

• See Best Practices Guide for detailed monitoring setup

Simple Production Monitor:

from datetime import datetime

# Simple periodic check (run as cron job or scheduler)
def check_and_alert(client, table_name, column_name):
    stats = client.vector_ops.get_ivf_stats(table_name, column_name)
    counts = stats['distribution']['centroid_count']
    balance = max(counts) / min(counts) if min(counts) > 0 else float('inf')

    status = "OK" if balance <= 2.5 else "CRITICAL"
    print(f"[{datetime.now()}] {table_name}: Balance={balance:.2f}, Status={status}")

    if status == "CRITICAL":
        # Send alert (email, Slack, PagerDuty, etc.)
        print(f"🚨 ALERT: Rebuild needed!")

check_and_alert(client, "documents", "embedding")

Note

get_ivf_stats works in transactions: tx.vector_ops.get_ivf_stats(table, column)

Pinecone-Compatible Interface

MatrixOne provides a Pinecone-compatible interface for easy migration from Pinecone:

from matrixone import Client
from matrixone.search_vector_index import PineconeCompatibleIndex

client = Client()
client.connect(host="127.0.0.1", port=6001, user="root", password="111", database="test")

# Create Pinecone-compatible index
index = PineconeCompatibleIndex(
    client=client,
    table_name="documents",
    vector_column="embedding",
    dimension=384
)

# Pinecone-style operations
index.upsert([
    {"id": "1", "values": [0.1, 0.2, 0.3] * 128, "metadata": {"title": "Document 1"}},
    {"id": "2", "values": [0.4, 0.5, 0.6] * 128, "metadata": {"title": "Document 2"}}
])

# Query with Pinecone-style interface
results = index.query(
    vector=[0.1, 0.2, 0.3] * 128,
    top_k=5,
    include_metadata=True
)

Next Steps

• Read the Vector Manager for detailed vector query API

• Check out the Vector Index Extensions for vector index management

• Learn about ORM Usage Guide for ORM patterns with vectors

• Check out the Examples for comprehensive usage examples