Unlocking Semantic Search and Generative-AI with Vector Databases on OCI: A Deep Dive into Oracle’s AI Vector Search

In the age of generative AI and LLM-driven applications, one of the biggest challenges enterprises face is how to connect their business-critical data (structured and unstructured) to AI models in a performant, scalable and governed way. Enter vector databases and vector search: these allow you to represent unstructured data (documents, images, embeddings) as high-dimensional “vectors”, index them for speedy similarity or semantic search, and combine them with relational business data.

With the Oracle stack — particularly the release of Oracle Database 23 ai / AI Database 26 ai — this capability is built into the database, giving you a unified platform for relational, JSON, spatial, graph and vector data.

In this article you’ll learn:

• What vector databases and vector search are, and why they matter for AI use-cases.
• How Oracle’s AI Vector Search works: data types, indexes, distance functions.
• A step-by-step example: ingest text embeddings into Oracle, query them via SQL using the VECTOR data type, combine with business metadata.
• Architectural and operational considerations: when to use, how to scale, best practices.
• Real-world use cases and governance implications.
  
  
  

Vector Databases & Why They Matter

What is a vector?

A vector is simply a list of numbers that represent features of an object: could be a sentence, document, image or audio snippet. By converting raw content into vectors (embeddings) via a model, you can perform similarity or semantic search in a high-dimensional space. Oracle+1

What is a vector database / vector search?

A vector database supports the storage, indexing and efficient querying of vectors — typically enabling nearest-neighbour or similarity search. According to Oracle:

“A vector database is any database that can natively store and manage vector embeddings and handle the unstructured data they describe.”

Importantly, in Oracle’s case, they’ve integrated vector search into their flagship database platform so you don’t need a separate vector store — you can keep relational data + vector embeddings in one system.

Why does this matter for AI and enterprise apps?

• Search not just by keywords, but by meaning. For example: “find all documents about contracts with high risk” might match content without the word “risk” explicitly.
• Enables Retrieval-Augmented Generation (RAG): your LLM can query your private business data (via vector search) and feed it into the prompt to generate more accurate responses.
• Combines unstructured data (embeddings) with structured business data (metadata, JSON, graph) in one platform — leading to simpler architecture, fewer data silos

How Oracle’s AI Vector Search Works

New data type: VECTOR

With Oracle Database 23 ai / AI Database 26 ai, the VECTOR data type is introduced: you can define table columns as VECTOR, store high-dimensional embeddings, and perform vector-specific operations.

Example:

CREATE TABLE docs (
  doc_id   INT,
  doc_text CLOB,
  doc_vector VECTOR  -- storing embedding
);

Vector Indexes & Distance Metrics

To deliver performant searches, Oracle supports vector indexes and distance functions (cosine, Euclidean, etc.). You can build indexes on the VECTOR column. oracle-base.com+1

SQL Example – similarity query:

SELECT doc_id, doc_text
FROM docs
WHERE vector_distance(doc_vector, :query_vector) < 0.3
ORDER BY vector_distance(doc_vector, :query_vector)
FETCH FIRST 10 ROWS ONLY;

Embedding generation & model support

You have two broad options:

• Generate embeddings externally (for example using an open-source transformer model) and load them into the VECTOR column.
• Use built-in or integrated embedding models (Oracle offers embedding generation or ONNX support) so that vector creation and storage is closer to the database.

Hybrid queries: relational + vector

Because everything is in the same database, you can combine structured filters (e.g., WHERE region = 'EMEA') with vector similarity queries. This enables richer semantics. Example: “Find contract documents similar to this one and related to Europe market” in one query.

Retrieval-Augmented Generation (RAG) support

By using vector search to fetch relevant documents and feeding them into your LLM prompt, you create a pipeline where your AI model is grounded in your private enterprise data. Oracle emphasises this with the AI Vector Search feature.

3. Example Walk-through: Text Embeddings + Similarity Search on OCI

Let’s walk through a practical example of how you might use Oracle AI Vector Search on OCI.

Step 1: Set up the environment

• Provision the Oracle AI Database 26 ai service in your OCI tenancy (or use Exadata/Autonomous with vector support).
• Ensure compatible version (VECTOR data type support requires version 23.7+ or similar). Oracle Documentation
• Create a user/table space for embeddings.

Step 2: Create tables for content and embeddings

CREATE TABLE knowledge_base (
  kb_id       NUMBER GENERATED BY DEFAULT AS IDENTITY,
  title       VARCHAR2(500),
  content     CLOB,
  embed_vector VECTOR
);

Step 3: Generate embeddings and load them

Example with Python using sentence-transformers to generate embeddings, and oracledb python driver to insert:

import oracledb
from sentence_transformers import SentenceTransformer

model = SentenceTransformer('all-MiniLM-L12-v2')
texts = ["Contract for vendor A", "Service Level Agreement for cloud services", ...]
embeds = model.encode(texts).tolist()

conn = oracledb.connect(user="vector_usr", password="pwd", dsn="your_dsn")
cursor = conn.cursor()

for text, embed in zip(texts, embeds):
    cursor.execute("""
        INSERT INTO knowledge_base(title, content, embed_vector)
        VALUES(:1, :2, :3)
    """, (text, text, embed))
conn.commit()

Step 4: Build a vector index (optional but recommended)

CREATE INDEX idx_kb_embed ON knowledge_base(embed_vector)
INDEXTYPE IS vector_ann INDEX_PARAMETERS('distance_metric=cosine, dimension=384');

Step 5: Run a similarity search query

Suppose you want documents similar to a query “cloud SLA compliance vendor”:

query_text = "cloud SLA compliance vendor"
query_embed = model.encode([query_text]).tolist()[0]

cursor.execute("""
  SELECT kb_id, title, vector_distance(embed_vector, :qb) AS dist
  FROM knowledge_base
  ORDER BY vector_distance(embed_vector, :qb)
  FETCH FIRST 5 ROWS ONLY
""", {"qb": query_embed})
for row in cursor:
    print(row)

Step 6: Combine with relational filters

For example: only search documents where region = 'EMEA' and then do vector search on their embeddings.

SELECT kb_id, title
FROM knowledge_base
WHERE region = 'EMEA'
ORDER BY vector_distance(embed_vector, :qb)
FETCH FIRST 5 ROWS ONLY;

Step 7: Build RAG pipeline

• Use vector search to fetch top K relevant documents for a given input.
• Pass those documents plus user input to an LLM in your application layer (OCI Functions, Data Science notebook, etc).
• Return generated answer citing which documents were used.
• Store feedback/metrics to refine embeddings over time.

4. Architecture & Operational Considerations

When to use vector databases

Use cases:

• Semantic document search across large unstructured corpora
• Recommendation engines (product similarity, content suggestions)
• Anomaly/outlier detection (embeddings of transactions or sessions)
• RAG workflows, chatbots backed by enterprise data

Architecture variations

• Fully integrated: Use Oracle AI Database / Exadata with vector support. One system for relational + vector.
• Hybrid: Vector store + separate LLM + service layer (if you already have a vector DB elsewhere). But the integrated approach simplifies data movement and governance.
  Oracle emphasises eliminating data silos by embedding vector search within the database.

Performance & scaling

• Choose appropriate vector index type (ANN, HNSW, IVF) according to scale.
• Ensure correct dimension of embeddings (e.g., 384, 768) and index parameters (e.g., nlist,nprobe).
• Use horizontal scalability: Oracle supports sharding, parallel SQL, and Exadata acceleration for vector workloads.
• Keep control of memory and storage: high-dimensional embeddings and large volumes need planning (embedding store size, index maintenance).

Data governance, security & maintainability

• Embeddings often represent sensitive data: apply encryption / access controls as you would relational data.
• Versioning of embeddings: if you regenerate embeddings (new model version), you need to update vectors & indexes.
• Monitoring & freshness: track metrics like query latency, drift in embeddings, relevance degradation.
• Explainability: embeddings are opaque. When building enterprise apps, you may need audit trails showing “why” a result was returned.

Best practices

• Define embedding generation strategy: consistent model, dimension size, pipeline for updating.
• Build hybrid search queries to mix semantic + business filters.
• Keep embedding tables small and well-partitioned (e.g., by date or region) if you expect high volumes.
• Automate index rebuilds/maintenance during low traffic periods.
• Cache top results where appropriate if you have frequent similar queries.
• Perform A/B testing: compare semantic search vs keyword search to measure lift.
• Document and govern vector fields: vector type, model version, embedding timestamp.

5. Use-Cases and Business Value

Use-case: Contract Search & Compliance

Imagine a legal department with thousands of contracts. Traditional keyword search misses meaning (“vendor terminated for cause”) if wording varies. With vector search you embed all contracts, allow semantic queries (“supplier termination risk Europe”), retrieve relevant ones quickly, and then feed into an LLM to summarise risk across contracts.

Use-case: Product Recommendation & RAG-enabled chatbot

Retailer: store product embeddings + user behaviour embeddings in vector table. When a user asks “What new hiking boots would you recommend given my past purchases?”, the system vector-searches similar items + user profile, then uses RAG+LLM to explain recommendations (“Based on your past purchase of Trailblazer 200 and preference for Gore-Tex, here are these three options…”).

Business value

• Faster time-to-insight from unstructured data.
• More relevant search & recommendations → higher engagement or productivity.
• Better AI confidence: feeding enterprise data through vector search into LLM reduces hallucinations by anchoring responses.
• Unified cost & architecture: no separate vector store means less operational overhead and fewer data-movement risks.