Database and Querying

Database opens and queries databases. See First Database with Rust for a tutorial.

Opening a Database

Basic Opening

#![allow(unused)]
fn main() {
use matchy::Database;

// Simple - uses defaults (cache enabled, validation on)
let db = Database::from("database.mxy").open()?;
}

The database is memory-mapped and loads in under 1 millisecond regardless of size.

Builder API

The recommended way to open databases uses the fluent builder API:

#![allow(unused)]
fn main() {
use matchy::Database;

// With custom cache size
let db = Database::from("database.mxy")
    .cache_capacity(1000)
    .open()?;

// Performance mode (skip validation, large cache)
let db = Database::from("threats.mxy")
    .trusted()
    .cache_capacity(100_000)
    .open()?;

// No cache (for unique queries)
let db = Database::from("database.mxy")
    .no_cache()
    .open()?;
}

Builder Methods

Cache Size Guidelines:

• 0 (via .no_cache()): No caching - best for diverse queries
• 100-1000: Good for moderate repetition
• 10,000 (default): Optimal for typical workloads
• 100,000+: For very high repetition (80%+ hit rate)

Note: Caching only benefits pattern lookups with high repetition. IP and literal lookups are already fast and don't benefit from caching.

Error Handling

#![allow(unused)]
fn main() {
match Database::open("database.mxy") {
    Ok(db) => { /* success */ }
    Err(MatchyError::FileNotFound { path }) => {
        eprintln!("Database not found: {}", path);
    }
    Err(MatchyError::InvalidFormat { reason }) => {
        eprintln!("Invalid database format: {}", reason);
    }
    Err(e) => eprintln!("Error: {}", e),
}
}

Querying

Method Signature

#![allow(unused)]
fn main() {
pub fn lookup<S: AsRef<str>>(&self, query: S) -> Result<Option<QueryResult>, MatchyError>
}

Basic Usage

#![allow(unused)]
fn main() {
match db.lookup("192.0.2.1")? {
    Some(result) => println!("Found: {:?}", result),
    None => println!("Not found"),
}
}

QueryResult Types

QueryResult is an enum with three variants:

IP Match

#![allow(unused)]
fn main() {
QueryResult::Ip {
    data: Option<HashMap<String, DataValue>>,
    prefix_len: u8,
}
}

Example:

#![allow(unused)]
fn main() {
match db.lookup("192.0.2.1")? {
    Some(QueryResult::Ip { data, prefix_len }) => {
        println!("Matched IP with prefix /{}", prefix_len);
        if let Some(d) = data {
            println!("Data: {:?}", d);
        }
    }
    _ => {}
}
}

Pattern Match

#![allow(unused)]
fn main() {
QueryResult::Pattern {
    pattern_ids: Vec<u32>,
    data: Vec<Option<HashMap<String, DataValue>>>,
}
}

Example:

#![allow(unused)]
fn main() {
match db.lookup("mail.google.com")? {
    Some(QueryResult::Pattern { pattern_ids, data }) => {
        println!("Matched {} pattern(s)", pattern_ids.len());
        for (i, pattern_data) in data.iter().enumerate() {
            println!("Pattern {}: {:?}", pattern_ids[i], pattern_data);
        }
    }
    _ => {}
}
}

Note: A query can match multiple patterns. All matching patterns are returned.

Exact String Match

#![allow(unused)]
fn main() {
QueryResult::ExactString {
    data: Option<HashMap<String, DataValue>>,
}
}

Example:

#![allow(unused)]
fn main() {
match db.lookup("example.com")? {
    Some(QueryResult::ExactString { data }) => {
        println!("Exact match: {:?}", data);
    }
    _ => {}
}
}

Complete Example

use matchy::{Database, QueryResult};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let db = Database::open("database.mxy")?;
    
    // Query different types
    let queries = vec![
        "192.0.2.1",           // IP
        "10.5.5.5",            // CIDR
        "test.example.com",    // Pattern
        "example.com",         // Exact string
    ];
    
    for query in queries {
        match db.lookup(query)? {
            Some(QueryResult::Ip { prefix_len, .. }) => {
                println!("{}: IP match (/{prefix_len})", query);
            }
            Some(QueryResult::Pattern { pattern_ids, .. }) => {
                println!("{}: Pattern match ({} patterns)", query, pattern_ids.len());
            }
            Some(QueryResult::ExactString { .. }) => {
                println!("{}: Exact match", query);
            }
            None => {
                println!("{}: No match", query);
            }
        }
    }
    
    Ok(())
}

Thread Safety

Database is Send + Sync and can be safely shared across threads:

#![allow(unused)]
fn main() {
use std::sync::Arc;
use std::thread;

let db = Arc::new(Database::open("database.mxy")?);

let handles: Vec<_> = (0..4).map(|i| {
    let db = Arc::clone(&db);
    thread::spawn(move || {
        db.lookup(&format!("192.0.2.{}", i))
    })
}).collect();

for handle in handles {
    handle.join().unwrap()?;
}
}

Performance

Query performance by entry type:

• IP addresses: ~7 million queries/second (138ns avg)
• Exact strings: ~8 million queries/second (112ns avg)
• Patterns: ~1-2 million queries/second (500ns-1μs avg)

See Performance Considerations for details.

Database Statistics

Get Statistics

Retrieve comprehensive statistics about database usage:

#![allow(unused)]
fn main() {
use matchy::Database;

let db = Database::from("threats.mxy").open()?;

// Do some queries
db.lookup("1.2.3.4")?;
db.lookup("example.com")?;
db.lookup("test.com")?;

// Get stats
let stats = db.stats();
println!("Total queries: {}", stats.total_queries);
println!("Queries with match: {}", stats.queries_with_match);
println!("Cache hit rate: {:.1}%", stats.cache_hit_rate() * 100.0);
println!("Match rate: {:.1}%", stats.match_rate() * 100.0);
println!("IP queries: {}", stats.ip_queries);
println!("String queries: {}", stats.string_queries);
}

DatabaseStats Structure

#![allow(unused)]
fn main() {
pub struct DatabaseStats {
    pub total_queries: u64,
    pub queries_with_match: u64,
    pub queries_without_match: u64,
    pub cache_hits: u64,
    pub cache_misses: u64,
    pub ip_queries: u64,
    pub string_queries: u64,
}

impl DatabaseStats {
    pub fn cache_hit_rate(&self) -> f64
    pub fn match_rate(&self) -> f64
}
}

Helper Methods:

• cache_hit_rate() - Returns cache hit rate as a value from 0.0 to 1.0
• match_rate() - Returns query match rate as a value from 0.0 to 1.0

Interpreting Statistics

Cache Performance:

• Hit rate < 50%: Consider disabling cache (.no_cache())
• Hit rate 50-80%: Cache is helping moderately
• Hit rate > 80%: Cache is very effective

Query Distribution:

• High ip_queries: Database is being used for IP lookups
• High string_queries: Database is being used for domain/pattern matching

Cache Management

Clear Cache

Remove all cached query results:

#![allow(unused)]
fn main() {
use matchy::Database;

let db = Database::from("threats.mxy").open()?;

// Do some queries (fills cache)
db.lookup("example.com")?;

// Clear cache to force fresh lookups
db.clear_cache();
}

Useful for benchmarking or when you need to ensure fresh lookups without reopening the database.

Helper Methods

Checking Entry Types

#![allow(unused)]
fn main() {
if let Some(QueryResult::Ip { .. }) = result {
    // Handle IP match
}
}

Or using match guards:

#![allow(unused)]
fn main() {
match db.lookup(query)? {
    Some(QueryResult::Ip { prefix_len, .. }) if prefix_len == 32 => {
        println!("Exact IP match");
    }
    Some(QueryResult::Ip { prefix_len, .. }) => {
        println!("CIDR match /{}", prefix_len);
    }
    _ => {}
}
}

Database Lifecycle

Databases are immutable once opened:

#![allow(unused)]
fn main() {
let db = Database::open("database.mxy")?;
// db.lookup(...) - OK
// db.add_entry(...) - No such method!
}

To update a database:

1. Build a new database with DatabaseBuilder
2. Write to a temporary file
3. Atomically replace the old database

#![allow(unused)]
fn main() {
// Build new database
let db_bytes = builder.build()?;
std::fs::write("database.mxy.tmp", &db_bytes)?;
std::fs::rename("database.mxy.tmp", "database.mxy")?;

// Reopen
let db = Database::open("database.mxy")?;
}

See Also

• DatabaseBuilder - Building databases
• Data Types Reference - Data value types
• Performance Considerations - Optimization