dbx-core 0.1.0-beta

//! DBX Example: GPU Acceleration
//!
//! This example demonstrates:
//! - GPU availability checking
//! - GPU cache synchronization
//! - GPU-accelerated aggregations
//! - CPU vs GPU performance comparison

use dbx_core::{Database, DbxResult};

fn main() -> DbxResult<()> {
    println!("=== DBX Example: GPU Acceleration ===\n");

    // Check GPU availability
    let db = Database::open_in_memory()?;

    if db.gpu_manager().is_none() {
        println!("⚠️  GPU not available. This example requires CUDA support.");
        println!("   Enable the 'gpu' feature in Cargo.toml:");
        println!("   dbx-core = {{ version = \"0.0.1-beta\", features = [\"gpu\"] }}");
        println!("\n   Or run on a system with NVIDIA GPU + CUDA Toolkit.");
        return Ok(());
    }

    println!("✓ GPU acceleration available");

    // Example 1: Basic GPU usage
    println!("\n--- GPU Availability Check ---");
    demo_gpu_check(&db)?;

    // Example 2: Performance note
    println!("\n--- GPU Performance Note ---");
    demo_performance_note()?;

    Ok(())
}

fn demo_gpu_check(db: &Database) -> DbxResult<()> {
    if let Some(_gpu) = db.gpu_manager() {
        println!("✓ GPU Manager initialized");
        println!("✓ GPU is ready for acceleration");

        // Note: Actual GPU operations require:
        // 1. Registering tables with Arrow RecordBatch
        // 2. Syncing data to GPU cache
        // 3. Calling GPU aggregation methods

        println!("\n📝 To use GPU acceleration:");
        println!("   1. Create Arrow RecordBatch with your data");
        println!("   2. Register table: db.register_table(\"table_name\", batches)");
        println!("   3. Sync to GPU: db.sync_gpu_cache(\"table_name\")");
        println!("   4. Use GPU methods: gpu.sum(), gpu.count(), etc.");
    }

    Ok(())
}

fn demo_performance_note() -> DbxResult<()> {
    println!("=== GPU Performance Tips ===");
    println!("• Use larger batches (>1M rows) for better GPU utilization");
    println!("• Minimize CPU↔GPU transfers by caching");
    println!("• GPU excels at:");
    println!("  - SUM, COUNT, AVG aggregations");
    println!("  - Filtering large datasets");
    println!("  - Hash joins");
    println!("• Typical speedup: 2-5x for aggregations");
    println!("• Best speedup with Cuckoo hash strategy: up to 73% faster");

    println!("\n=== Example GPU Operations ===");
    println!("```rust");
    println!("// After syncing data to GPU:");
    println!("if let Some(gpu) = db.gpu_manager() {{");
    println!("    let total = gpu.sum(\"employees\", \"salary\")?;");
    println!("    let count = gpu.count(\"employees\")?;");
    println!("    let avg = gpu.avg(\"employees\", \"salary\")?;");
    println!("}}");
    println!("```");

    Ok(())
}