# Summary
- [Introduction](./introduction.md)
- [Overall Architecture](./architecture.md)
- [Module Overview](./modules/overview.md)
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- [Contributor's Guide](./contributing.md)
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- [SQL Front-End](./modules/sql.md)
- [Catalog](./modules/catalog.md)
- [Expression System](./modules/expression.md)
- [Query Plan](./modules/plan.md)
- [The Lifecycle of a Query](./plan/lifecycle.md)
- [Query Optimizer](./modules/optimizer.md)
- [Rule-Based Optimization](./optimizer/rules.md)
- [Execution Engine](./modules/execution.md)
- [The Volcano Model](./execution/volcano.md)
- [Transaction Manager](./modules/transaction.md)
- [MVCC and 2PL](./transaction/mvcc_and_2pl.md)
- [Storage Engine](./modules/storage.md)
- [Disk I/O](./storage/disk_io.md)
- [Page & Tuple Layout](./storage/page_layouts.md)
- [Table Heap & MVCC](./storage/table_heap.md)
- [Buffer Manager](./modules/buffer.md)
- [Page & Page Guards](./buffer/page.md)
- [The Buffer Pool](./buffer/buffer_pool.md)
- [Indexes](./modules/index.md)
- [B+Tree](./index/btree_index.md)
- [Recovery Manager (WAL)](./modules/recovery.md)
- [The ARIES Protocol](./recovery/aries.md)
- [Write-Ahead Logging](./recovery/wal.md)
- [Background Services](./modules/background.md)
- [Configuration](./modules/config.md)
- [Front-Ends (CLI / HTTP)](./modules/bin.md)
- [Testing & Documentation](./modules/tests.md)