Vector Stores: The Foundation of Modern AI-Powered Search and Retrieval
Vector stores have become the critical infrastructure layer enabling retrieval-augmented generation (RAG), semantic search, and recommendation systems across the AI landscape. Unlike traditional databases that rely on exact keyword matching, vector stores operate on mathematical representations of meaning, allowing systems to find conceptually similar content even when no words match.
847%
Growth in vector database adoption among enterprises
This explosive growth reflects the fundamental shift toward AI-native applications where semantic understanding trumps keyword matching.
Key Insight
Embeddings Transform Meaning Into Mathematics
Vector embeddings convert text, images, audio, and other content into dense numerical arrays that capture semantic meaning in high-dimensional space. When you embed the phrase 'machine learning engineer' and 'AI developer,' they'll occupy nearby positions in vector space despite sharing no common words.
Vector Search Architecture Flow
User Query
Embedding Model (20-...
Vector Index Search ...
Metadata Filtering
Vector Store Options on AWS
OpenSearch Serverless
Fully managed with automatic scaling from 0 to millions of q...
Native k-NN plugin with HNSW and IVF algorithms built-in
Pay-per-OCU pricing starting at $0.24/OCU-hour with 4 OCU mi...
Supports up to 16,000 dimensions per vector field
Aurora PostgreSQL pgvector
Familiar PostgreSQL interface with SQL-based vector queries
Combines vector search with relational data in single databa...
Instance-based pricing from $0.073/hour for db.t4g.medium
Supports up to 16,000 dimensions with latest pgvector versio...
N
Notion
Scaling Semantic Search to 100M+ Documents
Search latency improved from 450ms p99 to 89ms p99, while infrastructure costs d...
Framework
The DIMS Framework for Vector Store Selection
Data Volume & Velocity
Assess your current vector count and growth trajectory. Solutions that work at 1M vectors may fail c...
Integration Requirements
Evaluate how vectors interact with existing data. If you need ACID transactions combining vector upd...
Metadata Complexity
Consider your filtering requirements. Simple filters (tenant_id, timestamp) work everywhere. Complex...
SLA Requirements
Define your latency and availability targets. Real-time applications need p99 latencies under 100ms....
Embedding Model Lock-in Is Real
Your vector store contains embeddings generated by a specific model version. Switching embedding models requires re-embedding your entire corpus and rebuilding all indexes.
Creating a Vector-Enabled Table in Aurora PostgreSQL with pgvectorsql
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-- Enable the pgvector extension
CREATE EXTENSION IF NOT EXISTS vector;
-- Create a table for document embeddings
CREATE TABLE document_embeddings (
id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
document_id VARCHAR(255) NOT NULL,
chunk_index INTEGER NOT NULL,
content TEXT NOT NULL,
embedding vector(1536), -- OpenAI text-embedding-3-small dimension
metadata JSONB DEFAULT '{}',
tenant_id VARCHAR(100) NOT NULL,
Key Insight
Chunking Strategy Determines RAG Quality More Than Vector Store Choice
Before obsessing over vector store selection, recognize that how you chunk documents has 3-5x more impact on retrieval quality than infrastructure choices. Fixed-size chunking (512 tokens) is simple but often splits semantic units awkwardly.
Deploying OpenSearch Serverless for Vector Search
1
Create the Collection
2
Configure Network Access
3
Set Up Data Access Policies
4
Create the Vector Index
5
Configure Index Settings
Anti-Pattern: Storing Raw Text in Vector Indexes
❌ Problem
Index sizes balloon 10-50x larger than necessary, dramatically increasing costs ...
✓ Solution
Store only embeddings, document IDs, and essential filter metadata in your vecto...
Vector Store Production Readiness Checklist
A
Anthropic
Building Claude's Context Retrieval Infrastructure
The system handles 50,000 queries per second with p99 latency of 34ms. Cache hit...
Start with pgvector, Graduate to OpenSearch
For teams building their first RAG system, pgvector on Aurora PostgreSQL offers the fastest path to production. You likely already have PostgreSQL expertise, and the familiar SQL interface accelerates development.
Key Insight
Hybrid Search Combines Keyword and Semantic Retrieval
Pure vector search misses exact matches that keyword search handles perfectly—searching for 'error code E-4521' should return documents containing that exact string, not semantically similar error descriptions. Hybrid search combines BM25 keyword scoring with vector similarity, typically using reciprocal rank fusion to merge results.
Average vector search latency on OpenSearch Serverless
This benchmark reflects queries against indexes with 10 million 1536-dimensional vectors using HNSW with ef_search=100.
Framework
The Vector Store Cost Model
Storage Costs
Raw vector storage plus index overhead. HNSW indexes add 40-60% overhead. Calculate: (vector_count ×...
Compute Costs
Query processing and index maintenance. OpenSearch Serverless uses OCUs ($0.24/hour minimum 4 OCUs)....
Embedding Generation
Often the largest cost component. OpenAI text-embedding-3-small costs $0.02/1M tokens. At 500 tokens...
Data Transfer
Frequently overlooked but significant at scale. Cross-AZ transfer costs $0.01/GB. Embedding API call...
Framework
Vector Store Selection Matrix
Query Pattern Analysis
Evaluate whether your workload is read-heavy (RAG applications), write-heavy (continuous embedding u...
Scale Trajectory Assessment
Project your vector count growth over 12-24 months. If you're starting under 1 million vectors but e...
Integration Complexity Score
Audit your existing data infrastructure. If you already use PostgreSQL for application data, pgvecto...
Latency Budget Allocation
Define your P99 latency requirements. Real-time applications like chatbots need sub-100ms responses,...
N
Notion
Building AI-Powered Search Across 200 Million Pages
Achieved 89ms average query latency across their entire corpus, reduced infrastr...
OpenSearch Serverless vs Aurora pgvector: Deep Technical Analysis
OpenSearch Serverless
Native k-NN plugin with HNSW and IVF algorithms, supporting ...
Automatic scaling from 0 to thousands of OCUs based on query...
Built-in hybrid search combining BM25 text relevance with ve...
Distributed architecture handles billions of vectors across ...
Aurora PostgreSQL pgvector
pgvector extension supports up to 2,000 dimensions with HNSW...
Vertical scaling through instance resizing, horizontal read ...
Requires application-level implementation for hybrid search ...
Single-node index limits practical vector counts to 50-100 m...
Implementing Production-Grade RAG with OpenSearch Serverless
1
Create Collection with Optimal Settings
2
Design Your Index Mapping
3
Implement Chunking Pipeline
4
Generate and Index Embeddings
5
Build Query Pipeline with Reranking
Anti-Pattern: The Monolithic Vector Index
❌ Problem
Query relevance plummeted because the embedding space became polluted with seman...
✓ Solution
Implement domain-specific indices with a routing layer. Create separate indices ...
Hybrid Search Query with OpenSearch Serverlesspython
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from opensearchpy import OpenSearch, RequestsHttpConnection
from requests_aws4auth import AWS4Auth
import boto3
# Initialize client with IAM authentication
region = 'us-east-1'
service = 'aoss'
credentials = boto3.Session().get_credentials()
awsauth = AWS4Auth(credentials.access_key, credentials.secret_key,
region, service, session_token=credentials.token)
client = OpenSearch(
47%
Reduction in hallucinations with proper chunking strategies
Anthropic's research found that RAG systems using semantic chunking with appropriate overlap reduced hallucination rates by 47% compared to fixed-size chunking.
Key Insight
The Hidden Cost of Vector Dimension Inflation
Many teams default to OpenAI's text-embedding-ada-002 (1536 dimensions) or larger models without considering the compound costs. Each dimension adds storage, memory, and compute overhead that scales linearly with your vector count.
Vector Store Production Readiness Assessment
S
Stripe
Scaling Document Intelligence with Aurora pgvector
Achieved 45ms average query latency for their AI documentation assistant, reduce...
OpenSearch Serverless Cold Start Implications
OpenSearch Serverless can scale to zero OCUs during periods of inactivity, but cold starts add 30-60 seconds to the first query. For production RAG applications, configure minimum OCU capacity (at least 2 OCUs for search) to eliminate cold starts.
Framework
RAG Quality Optimization Loop
Retrieval Metrics Collection
Instrument your pipeline to log query text, retrieved chunks, relevance scores, and final LLM respon...
Based on failure analysis, form specific hypotheses (e.g., 'reducing chunk size from 512 to 256 toke...
Embedding Model Evaluation
Quarterly, benchmark your current embedding model against newer alternatives using your production q...
Aurora pgvector with Metadata Filteringpython
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import psycopg2
from pgvector.psycopg2 import register_vector
import numpy as np
# Connection with pgvector extension
conn = psycopg2.connect(
host="your-aurora-cluster.cluster-xxx.us-east-1.rds.amazonaws.com",
database="vectors_db",
user="admin",
password="your-password"
)
register_vector(conn)
Key Insight
Amazon Kendra: When Semantic Search Isn't Enough
While vector databases excel at semantic similarity, Amazon Kendra provides enterprise search capabilities that pure vector stores lack. Kendra's ML-powered ranking considers document authority, freshness, user feedback signals, and organizational context—factors that embedding similarity alone cannot capture.
Multi-Stage RAG Pipeline Architecture
User Query
Query Cache (ElastiC...
Query Embedding (Bed...
Metadata Filter (SQL...
Practice Exercise
Build a Hybrid Search Benchmark Suite
90 min
Leverage OpenSearch Index State Management
Configure ISM policies to automatically manage vector index lifecycle. Set up policies that move indices older than 30 days to warm storage (UltraWarm), reducing costs by 90% while maintaining query capability.
Anti-Pattern: Ignoring Query-Document Asymmetry
❌ Problem
Short queries produce embeddings that don't align well with document chunk embed...
✓ Solution
Use asymmetric embedding models designed for query-document retrieval (like Cohe...
Practice Exercise
Build a Complete RAG Pipeline with OpenSearch Serverless
Anti-Pattern: Using Single-Threaded Batch Indexing
❌ Problem
A 10 million document migration takes 2-3 days instead of 2-3 hours. During this...
✓ Solution
Implement parallel batch indexing with configurable concurrency. Use asyncio or ...
Embedding Model Lock-In Risk
Your vector store is tightly coupled to your embedding model's output dimensions and semantic space. Changing embedding models requires complete reindexing of all vectors—a process that can take days for large datasets and requires maintaining dual indexes during migration.
Practice Exercise
Build a Multi-Tenant Vector Search System
120 min
Framework
Vector Store Observability Framework
Query Performance Monitoring
Track latency distributions (p50, p95, p99) for embedding generation, vector search, and total reque...
Search Quality Metrics
Implement offline evaluation using labeled test sets to measure precision, recall, and NDCG. Track o...
AWS re:Invent 2023: Building RAG Applications with OpenSearch Serverless
video
pgvector GitHub Repository and Documentation
tool
LangChain Vector Store Integration Guide
article
Anti-Pattern: Ignoring Query Result Diversity
❌ Problem
LLM responses become repetitive and miss important information that exists in th...
✓ Solution
Implement Maximum Marginal Relevance (MMR) or similar diversity algorithms that ...
Maximum Marginal Relevance Implementationpython
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import numpy as np
from typing import List, Tuple
def maximal_marginal_relevance(
query_embedding: np.ndarray,
candidate_embeddings: np.ndarray,
candidate_contents: List[str],
k: int = 5,
lambda_param: float = 0.7,
initial_k: int = 20
) -> List[Tuple[int, str, float]]:
"""
Cost Optimization Through Tiered Storage
Implement a tiered vector storage strategy based on access patterns. Keep frequently accessed vectors (last 30 days, high-traffic documents) in your primary vector store with fast retrieval.
67%
of RAG system latency comes from embedding generation
Most teams focus on optimizing vector search when the real bottleneck is embedding API calls.
Practice Exercise
Implement Vector Search Caching Layer
45 min
Anti-Pattern: Treating Vector Search as Exact Match
❌ Problem
Applications fail silently when semantic search returns related but not exact ma...
✓ Solution
Design for probabilistic retrieval by implementing confidence thresholds and res...
Test with Production-Scale Data
Vector search performance characteristics change dramatically at scale. An index that performs perfectly with 100,000 vectors may have completely different latency and recall characteristics at 10 million vectors.
Chapter Complete!
AWS offers three primary vector store options: OpenSearch Se...
Production vector search requires comprehensive infrastructu...
Chunk size and overlap significantly impact retrieval qualit...
Hybrid search combining semantic vectors with keyword matchi...
Next: Start by deploying a proof-of-concept with OpenSearch Serverless using the code examples provided, indexing 10,000 representative documents from your corpus