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docs: add German (DE) documentation + update all docs for Sessions 10-12
New German documentation (docs/de/):
- index.md, quickstart.md, installation.md
- baraql.md, graph.md, vector.md, mcp.md

Updated English documentation:
- changelog.md: all Sessions 10-12 features
- graph.md: SQL GRAPH_TABLE, CREATE GRAPH, all 8 algorithms, Cypher, similarity_nodes, node2vec
- vector.md: hybrid RAG, chunk(), embed_text(), auto-embed, nl_to_sql(), schema_prompt()
- baraql.md: new AI & Cross-Modal Functions section, updated keyword tables
- mcp.md: MCP Server documentation (new file)
- index.md: added German (DE) language link
2026-05-17 16:15:45 +03:00

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# Vector Search Engine
Native HNSW and IVF-PQ indexes for similarity search with full SQL integration.
Includes AI pipeline for chunking, embedding, and hybrid RAG search.
## SQL Usage
### Creating Vector Columns
```sql
CREATE TABLE items (
id INT PRIMARY KEY,
embedding VECTOR(768)
);
```
The `VECTOR(n)` type stores float32 arrays of fixed dimension `n`.
### Inserting Vectors
```sql
INSERT INTO items (id, embedding) VALUES (1, '[0.1, 0.2, 0.3, ...]');
```
### Vector Distance Functions
```sql
-- Cosine distance (0 = identical, 1 = orthogonal)
SELECT id, cosine_distance(embedding, '[0.1, 0.2, 0.3]') AS dist FROM items;
-- Euclidean / L2 distance
SELECT id, euclidean_distance(embedding, '[0.1, 0.2, 0.3]') AS dist FROM items;
SELECT id, embedding <-> '[0.1, 0.2, 0.3]' AS dist FROM items;
-- Inner product (negative for minimization)
SELECT id, inner_product(embedding, '[0.1, 0.2, 0.3]') AS dist FROM items;
-- Manhattan / L1 distance
SELECT id, l1_distance(embedding, '[0.1, 0.2, 0.3]') AS dist FROM items;
```
### Nearest Neighbor Search
```sql
-- Top-10 nearest neighbors by cosine distance
SELECT id FROM items
ORDER BY cosine_distance(embedding, '[0.1, 0.2, 0.3]') ASC
LIMIT 10;
```
### Vector Indexes
```sql
-- Create HNSW index
CREATE INDEX idx_items_vec ON items(embedding) USING hnsw;
-- Index is automatically maintained on INSERT and UPDATE
```
## Hybrid RAG Search
```sql
-- Combined vector + FTS search with Reciprocal Rank Fusion reranking
SELECT hybrid_search('AI query', embedding, content, 10) AS result;
-- Filtered hybrid search
SELECT hybrid_search_filtered('AI query', embedding, content, 10, 'category', 'news') AS result;
-- Comma-separated IDs only
SELECT hybrid_search_ids('AI query', embedding, content, 10) AS result;
```
## AI Pipeline
### Text Chunking
```sql
-- Split text into overlapping chunks (max 1024 chars, 128 overlap)
SELECT chunk('Long text content here...', 1024, 128) AS result;
-- Returns: [{"index":0, "text":"...", "size":124}, ...]
```
Strategies: `paragraph`, `sentence`, `fixed`, `recursive` (default).
### Embedding Generation
```sql
-- Call external embedding service for a query vector
SELECT embed_text('query text here') AS result;
```
Configure the embedder via environment variables:
```bash
export BARADB_EMBED_ENDPOINT=http://localhost:11434/api/embeddings
export BARADB_EMBED_MODEL=nomic-embed-text
export BARADB_EMBED_API_KEY=sk-... # optional, for OpenAI
```
### Auto-Embedding on INSERT
When a VECTOR column is NULL on INSERT but a TEXT column has content, the embedding
is automatically generated (if an embedder is configured):
```sql
CREATE TABLE docs (id INTEGER PRIMARY KEY, content TEXT, embedding VECTOR(768));
CREATE INDEX docs_vec ON docs(embedding) USING hnsw;
-- embedding is automatically populated
INSERT INTO docs (id, content) VALUES (1, 'This text will be auto-embedded');
```
## Natural Language → SQL
```sql
-- Generate schema prompt for LLM context
SELECT schema_prompt('users') AS result;
-- Natural language to SQL (requires configured LLM)
SELECT nl_to_sql('Show all users over 25 years old', 'users') AS result;
```
LLM configuration:
```bash
export BARADB_LLM_ENDPOINT=http://localhost:11434/api/generate
export BARADB_LLM_MODEL=llama3
export BARADB_LLM_API_KEY=sk-... # optional
```
## Distance Metrics
| Metric | SQL Function | Description |
|--------|--------------|-------------|
| `cosine` | `cosine_distance(a, b)` | Cosine dissimilarity (1 - similarity) |
| `euclidean` | `euclidean_distance(a, b)` / `<->` | L2 distance |
| `dotproduct` | `inner_product(a, b)` | Negative dot product |
| `manhattan` | `l1_distance(a, b)` | L1 distance |
## Native Nim API
```nim
import barabadb/vector/engine
var idx = newHNSWIndex(dimensions = 128)
idx.insert(1, @[1.0'f32, 0.0'f32, ...], {"category": "A"}.toTable)
let results = idx.search(queryVector, k = 10)
let filtered = idx.searchWithFilter(queryVector, k = 10,
filter = proc(meta: Table[string, string]): bool = "category" in meta)
```
## Index Types
### HNSW (Default)
```nim
var hnsw = newHNSWIndex(dimensions = 128, m = 16, efConstruction = 200)
```
### IVF-PQ
```nim
var ivfpq = newIVFPQIndex(dimensions = 128, numCentroids = 256, subQuantizers = 8)
```
## Quantization
```nim
import barabadb/vector/quant
let scalar = scalarQuantize(data, bits = 8)
let pq = productQuantize(data, subVectors = 8, bits = 8)
```
## SIMD Acceleration
```nim
import barabadb/vector/simd
let dist = simdCosineDistance(vec1, vec2)
```