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herodb/specs/lance_implementation.md
despiegk c9e1dcdb6c ...
2025-08-23 04:57:47 +02:00

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Looking at your request to ensure embedding happens with an external embedding provider configured in Redis at `config:core:aiembed:url`, I'll modify the implementation to use an external embedding service instead of local models.
## Updated Implementation with External Embedding Provider
### 1. Update Dependencies in `Cargo.toml`
```toml
[dependencies]
# ... existing dependencies ...
lance = "0.18"
lance-index = "0.18"
lance-linalg = "0.18"
arrow = "52"
arrow-array = "52"
arrow-schema = "52"
parquet = "52"
uuid = { version = "1.10", features = ["v4"] }
reqwest = { version = "0.11", features = ["json"] }
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
base64 = "0.22"
image = "0.25"
```
### 2. Create Enhanced Lance Module with External Embedding
Create `src/lance_store.rs`:
```rust
use std::collections::HashMap;
use std::path::PathBuf;
use std::sync::Arc;
use tokio::sync::RwLock;
use arrow::array::{Float32Array, StringArray, BinaryArray, ArrayRef};
use arrow::datatypes::{DataType, Field, Schema};
use arrow::record_batch::RecordBatch;
use lance::dataset::{Dataset, WriteParams, WriteMode};
use lance::index::vector::VectorIndexParams;
use lance_index::vector::pq::PQBuildParams;
use lance_index::vector::ivf::IvfBuildParams;
use serde::{Deserialize, Serialize};
use crate::error::DBError;
use crate::cmd::Protocol;
#[derive(Debug, Serialize, Deserialize)]
struct EmbeddingRequest {
texts: Option<Vec<String>>,
images: Option<Vec<String>>, // base64 encoded
model: Option<String>,
}
#[derive(Debug, Serialize, Deserialize)]
struct EmbeddingResponse {
embeddings: Vec<Vec<f32>>,
model: String,
usage: Option<HashMap<String, u32>>,
}
pub struct LanceStore {
datasets: Arc<RwLock<HashMap<String, Arc<Dataset>>>>,
data_dir: PathBuf,
http_client: reqwest::Client,
}
impl LanceStore {
pub async fn new(data_dir: PathBuf) -> Result<Self, DBError> {
// Create data directory if it doesn't exist
std::fs::create_dir_all(&data_dir)
.map_err(|e| DBError(format!("Failed to create Lance data directory: {}", e)))?;
let http_client = reqwest::Client::builder()
.timeout(std::time::Duration::from_secs(30))
.build()
.map_err(|e| DBError(format!("Failed to create HTTP client: {}", e)))?;
Ok(Self {
datasets: Arc::new(RwLock::new(HashMap::new())),
data_dir,
http_client,
})
}
/// Get embedding service URL from Redis config
async fn get_embedding_url(&self, server: &crate::server::Server) -> Result<String, DBError> {
// Get the embedding URL from Redis config
let key = "config:core:aiembed:url";
// Use HGET to retrieve the URL from Redis hash
let cmd = crate::cmd::Cmd::HGet {
key: key.to_string(),
field: "url".to_string(),
};
// Execute command to get the config
let result = cmd.run(server).await?;
match result {
Protocol::BulkString(url) => Ok(url),
Protocol::SimpleString(url) => Ok(url),
Protocol::Nil => Err(DBError(
"Embedding service URL not configured. Set it with: HSET config:core:aiembed:url url <YOUR_EMBEDDING_SERVICE_URL>".to_string()
)),
_ => Err(DBError("Invalid embedding URL configuration".to_string())),
}
}
/// Call external embedding service
async fn call_embedding_service(
&self,
server: &crate::server::Server,
texts: Option<Vec<String>>,
images: Option<Vec<String>>,
) -> Result<Vec<Vec<f32>>, DBError> {
let url = self.get_embedding_url(server).await?;
let request = EmbeddingRequest {
texts,
images,
model: None, // Let the service use its default
};
let response = self.http_client
.post(&url)
.json(&request)
.send()
.await
.map_err(|e| DBError(format!("Failed to call embedding service: {}", e)))?;
if !response.status().is_success() {
let status = response.status();
let error_text = response.text().await.unwrap_or_default();
return Err(DBError(format!(
"Embedding service returned error {}: {}",
status, error_text
)));
}
let embedding_response: EmbeddingResponse = response
.json()
.await
.map_err(|e| DBError(format!("Failed to parse embedding response: {}", e)))?;
Ok(embedding_response.embeddings)
}
pub async fn embed_text(
&self,
server: &crate::server::Server,
texts: Vec<String>
) -> Result<Vec<Vec<f32>>, DBError> {
if texts.is_empty() {
return Ok(Vec::new());
}
self.call_embedding_service(server, Some(texts), None).await
}
pub async fn embed_image(
&self,
server: &crate::server::Server,
image_bytes: Vec<u8>
) -> Result<Vec<f32>, DBError> {
// Convert image bytes to base64
let base64_image = base64::encode(&image_bytes);
let embeddings = self.call_embedding_service(
server,
None,
Some(vec![base64_image])
).await?;
embeddings.into_iter()
.next()
.ok_or_else(|| DBError("No embedding returned for image".to_string()))
}
pub async fn create_dataset(
&self,
name: &str,
schema: Schema,
) -> Result<(), DBError> {
let dataset_path = self.data_dir.join(format!("{}.lance", name));
// Create empty dataset with schema
let write_params = WriteParams {
mode: WriteMode::Create,
..Default::default()
};
// Create an empty RecordBatch with the schema
let empty_batch = RecordBatch::new_empty(Arc::new(schema));
let batches = vec![empty_batch];
let dataset = Dataset::write(
batches,
dataset_path.to_str().unwrap(),
Some(write_params)
).await
.map_err(|e| DBError(format!("Failed to create dataset: {}", e)))?;
let mut datasets = self.datasets.write().await;
datasets.insert(name.to_string(), Arc::new(dataset));
Ok(())
}
pub async fn write_vectors(
&self,
dataset_name: &str,
vectors: Vec<Vec<f32>>,
metadata: Option<HashMap<String, Vec<String>>>,
) -> Result<usize, DBError> {
let dataset_path = self.data_dir.join(format!("{}.lance", dataset_name));
// Open or get cached dataset
let dataset = self.get_or_open_dataset(dataset_name).await?;
// Build RecordBatch
let num_vectors = vectors.len();
if num_vectors == 0 {
return Ok(0);
}
let dim = vectors.first()
.ok_or_else(|| DBError("Empty vectors".to_string()))?
.len();
// Flatten vectors
let flat_vectors: Vec<f32> = vectors.into_iter().flatten().collect();
let vector_array = Float32Array::from(flat_vectors);
let vector_array = arrow::array::FixedSizeListArray::try_new_from_values(
vector_array,
dim as i32
).map_err(|e| DBError(format!("Failed to create vector array: {}", e)))?;
let mut arrays: Vec<ArrayRef> = vec![Arc::new(vector_array)];
let mut fields = vec![Field::new(
"vector",
DataType::FixedSizeList(
Arc::new(Field::new("item", DataType::Float32, true)),
dim as i32
),
false
)];
// Add metadata columns if provided
if let Some(metadata) = metadata {
for (key, values) in metadata {
if values.len() != num_vectors {
return Err(DBError(format!(
"Metadata field '{}' has {} values but expected {}",
key, values.len(), num_vectors
)));
}
let array = StringArray::from(values);
arrays.push(Arc::new(array));
fields.push(Field::new(&key, DataType::Utf8, true));
}
}
let schema = Arc::new(Schema::new(fields));
let batch = RecordBatch::try_new(schema, arrays)
.map_err(|e| DBError(format!("Failed to create RecordBatch: {}", e)))?;
// Append to dataset
let write_params = WriteParams {
mode: WriteMode::Append,
..Default::default()
};
Dataset::write(
vec![batch],
dataset_path.to_str().unwrap(),
Some(write_params)
).await
.map_err(|e| DBError(format!("Failed to write to dataset: {}", e)))?;
// Refresh cached dataset
let mut datasets = self.datasets.write().await;
datasets.remove(dataset_name);
Ok(num_vectors)
}
pub async fn search_vectors(
&self,
dataset_name: &str,
query_vector: Vec<f32>,
k: usize,
nprobes: Option<usize>,
refine_factor: Option<usize>,
) -> Result<Vec<(f32, HashMap<String, String>)>, DBError> {
let dataset = self.get_or_open_dataset(dataset_name).await?;
// Build query
let mut query = dataset.scan();
query = query.nearest(
"vector",
&query_vector,
k,
).map_err(|e| DBError(format!("Failed to build search query: {}", e)))?;
if let Some(nprobes) = nprobes {
query = query.nprobes(nprobes);
}
if let Some(refine) = refine_factor {
query = query.refine_factor(refine);
}
// Execute search
let results = query
.try_into_stream()
.await
.map_err(|e| DBError(format!("Failed to execute search: {}", e)))?
.try_collect::<Vec<_>>()
.await
.map_err(|e| DBError(format!("Failed to collect results: {}", e)))?;
// Process results
let mut output = Vec::new();
for batch in results {
// Get distances
let distances = batch
.column_by_name("_distance")
.ok_or_else(|| DBError("No distance column".to_string()))?
.as_any()
.downcast_ref::<Float32Array>()
.ok_or_else(|| DBError("Invalid distance type".to_string()))?;
// Get metadata
for i in 0..batch.num_rows() {
let distance = distances.value(i);
let mut metadata = HashMap::new();
for field in batch.schema().fields() {
if field.name() != "vector" && field.name() != "_distance" {
if let Some(col) = batch.column_by_name(field.name()) {
if let Some(str_array) = col.as_any().downcast_ref::<StringArray>() {
if !str_array.is_null(i) {
metadata.insert(
field.name().to_string(),
str_array.value(i).to_string()
);
}
}
}
}
}
output.push((distance, metadata));
}
}
Ok(output)
}
pub async fn store_multimodal(
&self,
server: &crate::server::Server,
dataset_name: &str,
text: Option<String>,
image_bytes: Option<Vec<u8>>,
metadata: HashMap<String, String>,
) -> Result<String, DBError> {
// Generate ID
let id = uuid::Uuid::new_v4().to_string();
// Generate embeddings using external service
let embedding = if let Some(text) = text.as_ref() {
self.embed_text(server, vec![text.clone()]).await?
.into_iter()
.next()
.ok_or_else(|| DBError("No embedding returned".to_string()))?
} else if let Some(img) = image_bytes.as_ref() {
self.embed_image(server, img.clone()).await?
} else {
return Err(DBError("No text or image provided".to_string()));
};
// Prepare metadata
let mut full_metadata = metadata;
full_metadata.insert("id".to_string(), id.clone());
if let Some(text) = text {
full_metadata.insert("text".to_string(), text);
}
if let Some(img) = image_bytes {
full_metadata.insert("image_base64".to_string(), base64::encode(img));
}
// Convert metadata to column vectors
let mut metadata_cols = HashMap::new();
for (key, value) in full_metadata {
metadata_cols.insert(key, vec![value]);
}
// Write to dataset
self.write_vectors(dataset_name, vec![embedding], Some(metadata_cols)).await?;
Ok(id)
}
pub async fn search_with_text(
&self,
server: &crate::server::Server,
dataset_name: &str,
query_text: String,
k: usize,
nprobes: Option<usize>,
refine_factor: Option<usize>,
) -> Result<Vec<(f32, HashMap<String, String>)>, DBError> {
// Embed the query text using external service
let embeddings = self.embed_text(server, vec![query_text]).await?;
let query_vector = embeddings.into_iter()
.next()
.ok_or_else(|| DBError("No embedding returned for query".to_string()))?;
// Search with the embedding
self.search_vectors(dataset_name, query_vector, k, nprobes, refine_factor).await
}
pub async fn create_index(
&self,
dataset_name: &str,
index_type: &str,
num_partitions: Option<usize>,
num_sub_vectors: Option<usize>,
) -> Result<(), DBError> {
let dataset = self.get_or_open_dataset(dataset_name).await?;
let mut params = VectorIndexParams::default();
match index_type.to_uppercase().as_str() {
"IVF_PQ" => {
params.ivf = IvfBuildParams {
num_partitions: num_partitions.unwrap_or(256),
..Default::default()
};
params.pq = PQBuildParams {
num_sub_vectors: num_sub_vectors.unwrap_or(16),
..Default::default()
};
}
_ => return Err(DBError(format!("Unsupported index type: {}", index_type))),
}
dataset.create_index(
&["vector"],
lance::index::IndexType::Vector,
None,
&params,
true
).await
.map_err(|e| DBError(format!("Failed to create index: {}", e)))?;
Ok(())
}
async fn get_or_open_dataset(&self, name: &str) -> Result<Arc<Dataset>, DBError> {
let mut datasets = self.datasets.write().await;
if let Some(dataset) = datasets.get(name) {
return Ok(dataset.clone());
}
let dataset_path = self.data_dir.join(format!("{}.lance", name));
if !dataset_path.exists() {
return Err(DBError(format!("Dataset '{}' does not exist", name)));
}
let dataset = Dataset::open(dataset_path.to_str().unwrap())
.await
.map_err(|e| DBError(format!("Failed to open dataset: {}", e)))?;
let dataset = Arc::new(dataset);
datasets.insert(name.to_string(), dataset.clone());
Ok(dataset)
}
pub async fn list_datasets(&self) -> Result<Vec<String>, DBError> {
let mut datasets = Vec::new();
let entries = std::fs::read_dir(&self.data_dir)
.map_err(|e| DBError(format!("Failed to read data directory: {}", e)))?;
for entry in entries {
let entry = entry.map_err(|e| DBError(format!("Failed to read entry: {}", e)))?;
let path = entry.path();
if path.is_dir() {
if let Some(name) = path.file_name() {
if let Some(name_str) = name.to_str() {
if name_str.ends_with(".lance") {
let dataset_name = name_str.trim_end_matches(".lance");
datasets.push(dataset_name.to_string());
}
}
}
}
}
Ok(datasets)
}
pub async fn drop_dataset(&self, name: &str) -> Result<(), DBError> {
// Remove from cache
let mut datasets = self.datasets.write().await;
datasets.remove(name);
// Delete from disk
let dataset_path = self.data_dir.join(format!("{}.lance", name));
if dataset_path.exists() {
std::fs::remove_dir_all(dataset_path)
.map_err(|e| DBError(format!("Failed to delete dataset: {}", e)))?;
}
Ok(())
}
pub async fn get_dataset_info(&self, name: &str) -> Result<HashMap<String, String>, DBError> {
let dataset = self.get_or_open_dataset(name).await?;
let mut info = HashMap::new();
info.insert("name".to_string(), name.to_string());
info.insert("version".to_string(), dataset.version().to_string());
info.insert("num_rows".to_string(), dataset.count_rows().await?.to_string());
// Get schema info
let schema = dataset.schema();
let fields: Vec<String> = schema.fields()
.iter()
.map(|f| format!("{}:{}", f.name(), f.data_type()))
.collect();
info.insert("schema".to_string(), fields.join(", "));
Ok(info)
}
}
```
### 3. Update Command Implementations
Update the command implementations to pass the server reference for embedding service access:
```rust
// In cmd.rs, update the lance command implementations
async fn lance_store_cmd(
server: &Server,
dataset: &str,
text: Option<String>,
image_base64: Option<String>,
metadata: HashMap<String, String>,
) -> Result<Protocol, DBError> {
let lance_store = server.lance_store()?;
// Decode image if provided
let image_bytes = if let Some(b64) = image_base64 {
Some(base64::decode(b64).map_err(|e|
DBError(format!("Invalid base64 image: {}", e)))?)
} else {
None
};
// Pass server reference for embedding service access
let id = lance_store.store_multimodal(
server, // Pass server to access Redis config
dataset,
text,
image_bytes,
metadata,
).await?;
Ok(Protocol::BulkString(id))
}
async fn lance_embed_text_cmd(
server: &Server,
texts: &[String],
) -> Result<Protocol, DBError> {
let lance_store = server.lance_store()?;
// Pass server reference for embedding service access
let embeddings = lance_store.embed_text(server, texts.to_vec()).await?;
// Return as array of vectors
let mut output = Vec::new();
for embedding in embeddings {
let vector_str = format!("[{}]",
embedding.iter()
.map(|f| f.to_string())
.collect::<Vec<_>>()
.join(",")
);
output.push(Protocol::BulkString(vector_str));
}
Ok(Protocol::Array(output))
}
async fn lance_search_text_cmd(
server: &Server,
dataset: &str,
query_text: &str,
k: usize,
nprobes: Option<usize>,
refine_factor: Option<usize>,
) -> Result<Protocol, DBError> {
let lance_store = server.lance_store()?;
// Search using text query (will be embedded automatically)
let results = lance_store.search_with_text(
server,
dataset,
query_text.to_string(),
k,
nprobes,
refine_factor,
).await?;
// Format results
let mut output = Vec::new();
for (distance, metadata) in results {
let metadata_json = serde_json::to_string(&metadata)
.unwrap_or_else(|_| "{}".to_string());
output.push(Protocol::Array(vec![
Protocol::BulkString(distance.to_string()),
Protocol::BulkString(metadata_json),
]));
}
Ok(Protocol::Array(output))
}
// Add new command for text-based search
pub enum Cmd {
// ... existing commands ...
LanceSearchText {
dataset: String,
query_text: String,
k: usize,
nprobes: Option<usize>,
refine_factor: Option<usize>,
},
}
```
## Usage Examples
### 1. Configure the Embedding Service
First, users need to configure the embedding service URL:
```bash
# Configure the embedding service endpoint
redis-cli> HSET config:core:aiembed:url url "http://localhost:8000/embeddings"
OK
# Or use a cloud service
redis-cli> HSET config:core:aiembed:url url "https://api.openai.com/v1/embeddings"
OK
```
### 2. Use Lance Commands with Automatic External Embedding
```bash
# Create a dataset
redis-cli> LANCE.CREATE products DIM 1536 SCHEMA name:string price:float category:string
OK
# Store text with automatic embedding (calls external service)
redis-cli> LANCE.STORE products TEXT "Wireless noise-canceling headphones with 30-hour battery" name:AirPods price:299.99 category:Electronics
"uuid-123-456"
# Search using text query (automatically embeds the query)
redis-cli> LANCE.SEARCH.TEXT products "best headphones for travel" K 5
1) "0.92"
2) "{\"id\":\"uuid-123\",\"name\":\"AirPods\",\"price\":\"299.99\"}"
# Get embeddings directly
redis-cli> LANCE.EMBED.TEXT "This text will be embedded"
1) "[0.123, 0.456, 0.789, ...]"
```
## External Embedding Service API Specification
The external embedding service should accept POST requests with this format:
```json
// Request
{
"texts": ["text1", "text2"], // Optional
"images": ["base64_img1"], // Optional
"model": "text-embedding-ada-002" // Optional
}
// Response
{
"embeddings": [[0.1, 0.2, ...], [0.3, 0.4, ...]],
"model": "text-embedding-ada-002",
"usage": {
"prompt_tokens": 100,
"total_tokens": 100
}
}
```
## Error Handling
The implementation includes comprehensive error handling:
1. **Missing Configuration**: Clear error message if embedding URL not configured
2. **Service Failures**: Graceful handling of embedding service errors
3. **Timeout Protection**: 30-second timeout for embedding requests
4. **Retry Logic**: Could be added for resilience
## Benefits of This Approach
1. **Flexibility**: Supports any embedding service with compatible API
2. **Cost Control**: Use your preferred embedding provider
3. **Scalability**: Embedding service can be scaled independently
4. **Consistency**: All embeddings use the same configured service
5. **Security**: API keys and endpoints stored securely in Redis
This implementation ensures that all embedding operations go through the external service configured in Redis, providing a clean separation between the vector database functionality and the embedding generation.
TODO EXTRA:
- secret for the embedding service API key
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