supertable-core 0.1.0

Core library for SuperTable, a next-generation open table format
Documentation
//! # Table Optimization
//!
//! This module provides tools for optimizing table layout, such as compacting small files
//! (bin-packing) and sorting data (Z-Ordering).

use crate::table::Table;
use crate::transaction::Transaction;
use anyhow::Result;

/// Options for compaction.
#[derive(Debug, Clone)]
pub struct CompactOptions {
    /// Target file size in bytes (e.g., 128MB).
    pub target_size_bytes: u64,
    /// Minimum number of files to trigger compaction.
    pub min_files_to_compact: usize,
    /// Filter for compaction
    pub filter: Option<String>,
}

impl Default for CompactOptions {
    fn default() -> Self {
        Self {
            target_size_bytes: 128 * 1024 * 1024,
            min_files_to_compact: 5,
            filter: None,
        }
    }
}

/// Scheduler for running compaction tasks.
pub struct CompactionScheduler {
    // Placeholder for scheduler state
}

impl CompactionScheduler {
    pub fn new() -> Self {
        Self {}
    }

    pub async fn schedule_compaction(&self, _table: &Table) -> Result<()> {
        // Placeholder
        Ok(())
    }
}

/// Strategy for compaction.
#[derive(Debug, Clone)]
pub enum CompactionStrategy {
    /// Combines small files into larger ones.
    BinPack,
    /// Sorts data by specific columns (e.g., Z-Order).
    Sort {
        /// Columns to sort by.
        sort_columns: Vec<String>,
    },
}

/// Main optimizer entry point.
pub struct Optimizer {
    table: Table,
    options: CompactOptions,
    strategy: CompactionStrategy,
}

impl Optimizer {
    pub fn new(table: Table) -> Self {
        Self {
            table,
            options: CompactOptions::default(),
            strategy: CompactionStrategy::BinPack,
        }
    }

    /// Sets the compaction options.
    pub fn with_options(mut self, options: CompactOptions) -> Self {
        self.options = options;
        self
    }

    /// Sets the compaction strategy.
    pub fn with_strategy(mut self, strategy: CompactionStrategy) -> Self {
        self.strategy = strategy;
        self
    }

    /// Executes the optimization.
    pub async fn execute(self) -> Result<Transaction> {
        let snapshot = self.table.metadata.current_snapshot();
        if snapshot.is_none() {
            return Ok(self.table.new_transaction());
        }
        let snapshot = snapshot.unwrap();

        let all_files = snapshot.all_data_files(&self.table.storage).await?;

        // Filter files based on self.filter (Placeholder)
        // Identify small files

        let mut files_to_compact = Vec::new();
        // let mut other_files = Vec::new();

        let target_size = self.options.target_size_bytes;

        for file in all_files {
            if (file.file_size_in_bytes as u64) < target_size {
                files_to_compact.push(file);
            } else {
                // other_files.push(file);
            }
        }

        if files_to_compact.len() < self.options.min_files_to_compact {
            return Ok(self.table.new_transaction());
        }

        // Implementation limitation:
        // Real compaction requires reading these files, merging them, and writing new ones.
        // For this prototype, we will just return a transaction that *would* replace them,
        // but since we can't easily read/write locally without full context, we'll
        // leave it as a placeholder that does no-op but compiles.

        // In a real implementation:
        // 1. Group files into bins of target_size
        // 2. Read each bin -> RecordBatch
        // 3. Write RecordBatch -> New DataFile
        // 4. Create Transaction: Remove old files, Add new files

        let tx = self.table.new_transaction();
        // tx.remove_files(files_to_compact.iter().map(|f| f.file_path.clone()).collect());
        // tx.add_files(new_files);

        Ok(tx)
    }
}