ChronoMemDB ⏱️💾

A lightweight, high‑performance in‑memory database engine written in modern C++.

ChronoMemDB is a teaching/portfolio‑grade engine that focuses on clear architecture and extendability. It ships with a minimal storage layer, skeleton B+Tree index, a tiny SQL‑like REPL, and hooks for transactions and logging.

Status: Starter template — compile‑ready, unit‑tested stubs, and room to grow.

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✨ Features (MVP)

• In‑memory row store (example users table)
• Clean interfaces for Storage, Index, Transactions, and Query Processor
• Tiny SQL‑like commands (subset): CREATE, INSERT, SELECT (very limited)
• C++17 codebase with CMake build

🧭 Roadmap (Next Steps)

• Implement B+Tree index for primary key
• Add WHERE filters, range scans, and projections
• Introduce TransactionManager with WAL (Write‑Ahead Logging)
• Add persistence layer (snapshot + redo log)
• MVCC for concurrent readers/writers
• Proper parser (e.g., PEGTL) — currently a hand‑rolled minimal parser

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🔧 Build

mkdir build && cd build
cmake ..
cmake --build . -j
./chrono_mem_db

Requirements

• C++17 compatible compiler (GCC 9+/Clang 10+/MSVC 2019+)
• CMake 3.15+

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🖥️ Usage (REPL)

Run the executable and enter commands (semicolon optional for simple commands):

CREATE TABLE users;
INSERT INTO users VALUES (1, Alice, 30);
SELECT * FROM users;
SELECT BY ID 1;
QUIT

Note: This is a learning scaffold; the parser is intentionally simple. Strings without spaces work out‑of‑the‑box; quote handling is left as an exercise.

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🗂️ Project Structure

ChronoMemDB/
  ├─ src/
  │   ├─ main.cpp
  │   ├─ storage.h / storage.cpp
  │   ├─ bptree.h  / bptree.cpp       (skeleton)
  │   ├─ transaction_manager.h / transaction_manager.cpp (skeleton)
  │   └─ query_parser.h / query_parser.cpp
  ├─ tests/
  │   └─ basic_tests.cpp
  ├─ docs/
  │   └─ ARCHITECTURE.md
  ├─ CMakeLists.txt
  ├─ .gitignore
  └─ LICENSE

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📚 License

MIT — see LICENSE.

🙌 Contributions

PRs are welcome. This repo is purposefully small and approachable; design notes in docs/ highlight how to extend each subsystem.