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Visual Guides/Vector Databases: Semantic Search
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Vector Databases: Semantic Search

Watch documents become vectors in 2D space. Run semantic queries and see nearest neighbors retrieved by cosine similarity, no keyword matching required.

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1The Vector Space

Each document is embedded as a point in vector space. Similar topics cluster together. Hover a dot to read its text.

Machine Learning
History
Food
Technology
★Query point

2Run a Query

Select a query to see it land in vector space. Lines show similarity to each document: the top 3 nearest are highlighted.

Click a query above to see the nearest neighbors retrieved from the vector index.

3Keyword vs Semantic Search

Query: “AI and neural nets”. See how each approach handles it.

Keyword SearchSQL LIKE '%neural%'
Deep neural networksexact match
“Machine learning basics”: not returned (no 'neural')
“Python for data science”: not returned (no 'neural')

1 result. Misses semantically related docs.

Semantic Searchcosine similarity
1.
Machine learning basics
2.
Deep neural networks
3.
Python for data science

3 results. Understands meaning, not just words.

4How It Works Under the Hood

Three stages from document to retrieval result.

1Embed
“Machine learning basics”↓ Embedding model[0.8, 0.7, -0.3, ...]1536 floats (OpenAI ada-002)
→
2Index (HNSW)
123456

Hierarchical Navigable Small World: O(log n) search

→
3ANN Retrieve
query vector↓ top-k ANN search
0.97 · doc A
0.94 · doc B
0.88 · doc C

5Popular Vector Databases

Choose the right tool for your use case.

DatabaseOpen SourceManagedBest For
PineconeNoYesProduction SaaS
WeaviateYesYesMulti-modal
QdrantYesYesHigh performance
pgvectorYesNoExisting Postgres
ChromaYesNoLocal dev
★

Key Insight

At 1M documents with 1536-dim vectors (OpenAI ada-002), you need approximately ~6 GB RAM just to store the index. Vector databases use specialized indexing (HNSW) to search millions of vectors in milliseconds; traditional SQL would require a full table scan, making it orders of magnitude slower.

Up Next

Chunking Strategies for RAG

Before you can store documents in a vector database, you need to split them into meaningful chunks. See fixed-size, recursive, and semantic chunking applied side by side.

Explore Chunking Strategies→
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