add data packages and remove empty submodule

packages/data/radixtree/README.md

@@ -0,0 +1,189 @@
+# RadixTree
+
+A persistent radix tree implementation in Rust using OurDB for storage.
+
+## Overview
+
+RadixTree is a space-optimized tree data structure that enables efficient string key operations with persistent storage. This implementation provides a persistent radix tree that can be used for efficient prefix-based key operations, such as auto-complete, routing tables, and more.
+
+A radix tree (also known as a patricia trie or radix trie) is a space-optimized tree data structure that enables efficient string key operations. Unlike a standard trie where each node represents a single character, a radix tree compresses paths by allowing nodes to represent multiple characters (key segments).
+
+Key characteristics:
+- Each node stores a segment of a key (not just a single character)
+- Nodes can have multiple children, each representing a different branch
+- Leaf nodes contain the actual values
+- Optimizes storage by compressing common prefixes
+
+## Features
+
+- Efficient prefix-based key operations
+- Persistent storage using OurDB backend
+- Memory-efficient storage of strings with common prefixes
+- Support for binary values
+- Thread-safe operations through OurDB
+
+## Usage
+
+Add the dependency to your `Cargo.toml`:
+
+```toml
+[dependencies]
+radixtree = { path = "../radixtree" }
+```
+
+### Basic Example
+
+```rust
+use radixtree::RadixTree;
+
+fn main() -> Result<(), radixtree::Error> {
+    // Create a new radix tree
+    let mut tree = RadixTree::new("/tmp/radix", false)?;
+    
+    // Set key-value pairs
+    tree.set("hello", b"world".to_vec())?;
+    tree.set("help", b"me".to_vec())?;
+    
+    // Get values by key
+    let value = tree.get("hello")?;
+    println!("hello: {}", String::from_utf8_lossy(&value)); // Prints: world
+    
+    // List keys by prefix
+    let keys = tree.list("hel")?; // Returns ["hello", "help"]
+    println!("Keys with prefix 'hel': {:?}", keys);
+    
+    // Get all values by prefix
+    let values = tree.getall("hel")?; // Returns [b"world", b"me"]
+    
+    // Delete keys
+    tree.delete("help")?;
+    
+    Ok(())
+}
+```
+
+## API
+
+### Creating a RadixTree
+
+```rust
+// Create a new radix tree
+let mut tree = RadixTree::new("/tmp/radix", false)?;
+
+// Create a new radix tree and reset if it exists
+let mut tree = RadixTree::new("/tmp/radix", true)?;
+```
+
+### Setting Values
+
+```rust
+// Set a key-value pair
+tree.set("key", b"value".to_vec())?;
+```
+
+### Getting Values
+
+```rust
+// Get a value by key
+let value = tree.get("key")?;
+```
+
+### Updating Values
+
+```rust
+// Update a value at a given prefix
+tree.update("prefix", b"new_value".to_vec())?;
+```
+
+### Deleting Keys
+
+```rust
+// Delete a key
+tree.delete("key")?;
+```
+
+### Listing Keys by Prefix
+
+```rust
+// List all keys with a given prefix
+let keys = tree.list("prefix")?;
+```
+
+### Getting All Values by Prefix
+
+```rust
+// Get all values for keys with a given prefix
+let values = tree.getall("prefix")?;
+```
+
+## Performance Characteristics
+
+- Search: O(k) where k is the key length
+- Insert: O(k) for new keys, may require node splitting
+- Delete: O(k) plus potential node cleanup
+- Space: O(n) where n is the total length of all keys
+
+## Use Cases
+
+RadixTree is particularly useful for:
+- Prefix-based searching
+- IP routing tables
+- Dictionary implementations
+- Auto-complete systems
+- File system paths
+- Any application requiring efficient string key operations with persistence
+
+## Implementation Details
+
+The RadixTree implementation uses OurDB for persistent storage:
+- Each node is serialized and stored as a record in OurDB
+- Node references use OurDB record IDs
+- The tree maintains a root node ID for traversal
+- Node serialization includes version tracking for format evolution
+
+For more detailed information about the implementation, see the [ARCHITECTURE.md](./ARCHITECTURE.md) file.
+
+## Running Tests
+
+The project includes a comprehensive test suite that verifies all functionality:
+
+```bash
+# Run all tests
+cargo test
+
+# Run specific test file
+cargo test --test basic_test
+cargo test --test prefix_test
+cargo test --test getall_test
+cargo test --test serialize_test
+```
+
+## Running Examples
+
+The project includes example applications that demonstrate how to use the RadixTree:
+
+```bash
+# Run the basic usage example
+cargo run --example basic_usage
+
+# Run the prefix operations example
+cargo run --example prefix_operations
+```
+
+## Benchmarking
+
+The project includes benchmarks to measure performance:
+
+```bash
+# Run all benchmarks
+cargo bench
+
+# Run specific benchmark
+cargo bench -- set
+cargo bench -- get
+cargo bench -- prefix_operations
+```
+
+## License
+
+This project is licensed under the same license as the HeroCode project.