URI Register

⚠️ Beta Software: This library is in active development and the API may change. While it's being used in production environments, you should pin to a specific version and test thoroughly before upgrading.

A high-performance, async-first PostgreSQL-backed URI register service for assigning unique integer IDs to URIs. Perfect for string interning, deduplication, and systems that need consistent global identifier mappings.

Note: This library is async-only and requires an async runtime (tokio).

Overview

The URI Register provides a simple, fast way to assign unique integer IDs to URI strings. Once registered, a URI always returns the same ID, making it ideal for string interning and deduplication in distributed systems.

Features

• Simple API: Just 2 methods - register_uri() and register_uri_batch()
• Async-only: Built on tokio/sqlx for high concurrency
• Batch optimised: Process thousands of URIs in a single database round-trip
• LRU caching: In-memory cache for frequently accessed URIs (configurable size)
• Order preservation: Batch operations maintain strict order correspondence
• PostgreSQL backend: Durable, scalable, with connection pooling
• Thread-safe: Designed for concurrent access from multiple threads/processes

Use Cases

• String interning systems: Reduce memory footprint by storing strings once and referencing by ID
• URL deduplication: Assign unique IDs to URLs across distributed crawlers
• Global identifier systems: Centralised ID assignment for URIs/strings in microservices
• Data warehousing: Efficient storage of repeated string values
• Distributed caching: Consistent ID assignment across cache nodes

Installation

Rust

Add to your Cargo.toml:

[dependencies]
uri-register = "0.1.2"

Or use as a git dependency:

[dependencies]
uri-register = { git = "https://github.com/telicent-oss/uri-register" }

Python

Install from TestPyPI (during beta):

pip install --index-url https://test.pypi.org/simple/ uri-register

Requirements: Python 3.8+

Note: The package is currently published to TestPyPI for testing. Once stable, it will be available on the main PyPI repository.

Setup

1. Database Initialisation

Before using the URI Register service, you must initialise the PostgreSQL schema.

Run the schema creation script:

psql -U username -d database_name -f schema.sql

Or execute the SQL directly:

CREATE TABLE IF NOT EXISTS uri_register (
    id BIGSERIAL PRIMARY KEY,
    uri TEXT NOT NULL UNIQUE
);

CREATE INDEX IF NOT EXISTS uri_register_uri_idx ON uri_register (uri);

2. Database Configuration

The service requires a PostgreSQL connection string. Set it as an environment variable or pass it directly:

export DATABASE_URL="postgresql://username:password@localhost:5432/database_name"

Usage

Rust Example

use uri_register::{UriService, PostgresUriRegister};

#[tokio::main]
async fn main() -> uri_register::Result<()> {
    // Connect to PostgreSQL
    let register = PostgresUriRegister::new("postgres://localhost/mydb").await?;

    // Register a single URI
    let id = register.register_uri("http://example.org/resource/1").await?;
    println!("Registered URI with ID: {}", id);

    // Register the same URI again - returns the same ID
    let same_id = register.register_uri("http://example.org/resource/1").await?;
    assert_eq!(id, same_id);

    // Register multiple URIs in batch (much faster!)
    let uris = vec![
        "http://example.org/resource/2".to_string(),
        "http://example.org/resource/3".to_string(),
        "http://example.org/resource/4".to_string(),
    ];
    let ids = register.register_uri_batch(&uris).await?;

    // IDs maintain order: ids[i] corresponds to uris[i]
    for (uri, id) in uris.iter().zip(ids.iter()) {
        println!("{} -> {}", uri, id);
    }

    Ok(())
}

Python Example

import asyncio
from uri_register import UriRegister

async def main():
    # Connect to PostgreSQL
    register = await UriRegister.new("postgres://localhost/mydb")

    # Register a single URI
    id = await register.register_uri("http://example.org/resource/1")
    print(f"Registered URI with ID: {id}")

    # Register the same URI again - returns the same ID
    same_id = await register.register_uri("http://example.org/resource/1")
    assert id == same_id

    # Register multiple URIs in batch (much faster!)
    uris = [
        "http://example.org/resource/2",
        "http://example.org/resource/3",
        "http://example.org/resource/4",
    ]
    ids = await register.register_uri_batch(uris)

    # IDs maintain order: ids[i] corresponds to uris[i]
    for uri, id in zip(uris, ids):
        print(f"{uri} -> {id}")

    # Get statistics
    stats = await register.stats()
    print(f"Total URIs: {stats['total_uris']}")

asyncio.run(main())

API Reference

The UriService trait provides two methods:

register_uri(uri: &str) -> u64

Register a single URI and return its ID.

• If the URI exists, returns the existing ID
• If the URI is new, creates a new ID and returns it
• Uses LRU cache for fast repeated lookups

let id = register.register_uri("http://example.org/page").await?;

register_uri_batch(uris: &[String]) -> Vec<u64>

Register multiple URIs in batch and return their IDs.

• Order preserved: ids[i] corresponds to uris[i]
• Much faster than calling register_uri() multiple times
• Handles duplicate URIs in input correctly
• Cache-optimised: only queries database for cache misses

let uris = vec![
    "http://example.org/page1".to_string(),
    "http://example.org/page2".to_string(),
];
let ids = register.register_uri_batch(&uris).await?;

// Access by index
assert_eq!(ids[0], register.register_uri("http://example.org/page1").await?);

Statistics

Get information about the register:

let stats = register.stats().await?;
println!("Total URIs: {}", stats.total_uris);
println!("Storage size: {} bytes", stats.size_bytes);

Performance

Logged Tables (Default)

With default logged tables on typical hardware:

• Single registration: ~500-1K URIs/sec (with cache: 100K+/sec)
• Batch registration: ~10K-50K URIs/sec
• Batch lookup (cached): ~1M+ URIs/sec (no DB round-trip)
• Batch lookup (uncached): ~100K-200K URIs/sec

Unlogged Tables (Optional)

For 2-3x faster writes at the cost of durability:

ALTER TABLE uri_register SET UNLOGGED;

Performance with unlogged tables:

• Batch registration: ~30K-150K URIs/sec

WARNING: Unlogged tables lose all data if PostgreSQL crashes. Only use this if you can rebuild the register from source data.

To revert back to logged mode:

ALTER TABLE uri_register SET LOGGED;

LRU Cache Configuration

The service includes an in-memory LRU cache that dramatically improves performance for repeated URI lookups. Configure the cache size via environment variable:

export URI_REGISTER_CACHE_SIZE=50000  # Default: 10,000 entries

The cache provides near-instant lookups for frequently accessed URIs, completely bypassing database queries.

Performance Tips

1. Always use batch operations when processing multiple URIs
2. Connection pooling is configured by default (20 max connections)
3. Batch size: Optimal batch size is typically 1K-10K URIs per operation
4. Indexing: The URI index is essential for lookup performance
5. Consider unlogged tables for initial bulk loading, then switch to logged
6. Tune cache size based on your working set size and available memory

Architecture

Application
    ↓
UriService trait (2 methods)
    ↓
PostgresUriRegister impl
    ↓  ↓
LRU Cache  Connection Pool (20 connections)
    ↓           ↓
    └─────→ PostgreSQL Database

Schema Details

The register uses a simple two-column table:

• id: BIGSERIAL primary key (auto-incrementing u64)
• uri: TEXT with UNIQUE constraint (indexed)

The UNIQUE constraint prevents duplicate URIs, and the index provides fast lookups.

Testing

For testing purposes, an in-memory implementation is available:

#[cfg(test)]
use uri_register::InMemoryUriRegister;

#[tokio::test]
async fn test_uri_register() {
    let register = InMemoryUriRegister::new();
    let id = register.register_uri("http://example.org").await.unwrap();
    assert_eq!(id, 1); // First URI gets ID 1
}

Examples

Rust

use uri_register::{UriService, PostgresUriRegister};

#[tokio::main]
async fn main() -> uri_register::Result<()> {
    // Connect to PostgreSQL with full connection parameters
    // Format: postgres://user:password@host:port/database
    let database_url = "postgres://myuser:mypassword@localhost:5432/mydb";
    let max_connections = 20;      // Connection pool size
    let cache_size = 50_000;       // LRU cache size

    let register = PostgresUriRegister::new(database_url, max_connections, cache_size).await?;

    // Register single URIs
    let id1 = register.register_uri("http://example.org/resource/1").await?;
    let id2 = register.register_uri("http://example.org/resource/2").await?;
    println!("Registered: {} -> ID {}", "resource/1", id1);
    println!("Registered: {} -> ID {}", "resource/2", id2);

    // Register the same URI again - returns the same ID
    let id1_again = register.register_uri("http://example.org/resource/1").await?;
    assert_eq!(id1, id1_again);

    // Batch registration (faster for multiple URIs)
    let uris = vec![
        "http://example.org/a".to_string(),
        "http://example.org/b".to_string(),
        "http://example.org/c".to_string(),
        "http://example.org/a".to_string(), // Duplicate
    ];
    let ids = register.register_uri_batch(&uris).await?;
    // Order preserved: ids[i] corresponds to uris[i]
    assert_eq!(ids[0], ids[3]); // Duplicates get same ID

    // Batch registration with hashmap (automatic deduplication)
    let mapping = register.register_uri_batch_hashmap(&uris).await?;
    println!("Unique URIs: {}", mapping.len()); // 3 unique URIs

    // Get statistics
    let stats = register.stats().await?;
    println!("Total URIs: {}", stats.total_uris);
    println!("Storage: {} bytes", stats.size_bytes);

    Ok(())
}

Python

import asyncio
from uri_register import UriRegister

async def main():
    # Connect to PostgreSQL with full connection parameters
    # Format: postgres://user:password@host:port/database
    database_url = "postgres://myuser:mypassword@localhost:5432/mydb"
    max_connections = 20      # Connection pool size
    cache_size = 50_000       # LRU cache size

    register = await UriRegister.new(database_url, max_connections, cache_size)

    # Register single URIs
    id1 = await register.register_uri("http://example.org/resource/1")
    id2 = await register.register_uri("http://example.org/resource/2")
    print(f"Registered: resource/1 -> ID {id1}")
    print(f"Registered: resource/2 -> ID {id2}")

    # Register the same URI again - returns the same ID
    id1_again = await register.register_uri("http://example.org/resource/1")
    assert id1 == id1_again

    # Batch registration (faster for multiple URIs)
    uris = [
        "http://example.org/a",
        "http://example.org/b",
        "http://example.org/c",
        "http://example.org/a",  # Duplicate
    ]
    ids = await register.register_uri_batch(uris)
    # Order preserved: ids[i] corresponds to uris[i]
    assert ids[0] == ids[3]  # Duplicates get same ID

    # Batch registration with hashmap (automatic deduplication)
    mapping = await register.register_uri_batch_hashmap(uris)
    print(f"Unique URIs: {len(mapping)}")  # 3 unique URIs

    # Get statistics
    stats = await register.stats()
    print(f"Total URIs: {stats['total_uris']}")
    print(f"Storage: {stats['size_bytes']} bytes")

asyncio.run(main())

Error Handling

The library uses custom error types for better error handling:

use uri_register::{Error, Result};

match register.register_uri("http://example.org").await {
    Ok(id) => println!("Registered with ID: {}", id),
    Err(Error::Database(e)) => eprintln!("Database error: {}", e),
    Err(Error::ConnectionPool(e)) => eprintln!("Connection pool error: {}", e),
    Err(e) => eprintln!("Other error: {}", e),
}

License

Licensed under the Apache License, Version 2.0 (LICENSE or http://www.apache.org/licenses/LICENSE-2.0).

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.