The Backend Engineering Show with Hussein Nasser The Internals of MongoDB
Feb 19, 2024
Explore the evolution of MongoDB's internal architecture, from document storage to index representation. Learn about page sizes in MongoDB, MySQL, and PostgreSQL. Delve into the importance of efficient disk I/O and backend engineering fundamentals. Discover the transition to document-oriented storage and cluster B-tree indexing in MongoDB, comparing it with other DBMS.
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Database Core Architecture
- Databases fundamentally consist of a front end (API) and a storage engine handling how data is stored on disk.
- The storage engine treats all data as bytes in fixed-size pages, optimizing I/O efficiency rather than data format.
Durability via Write-Ahead Logs
- Databases use a write-ahead log (WAL) to ensure durability and aid crash recovery.
- Changes are first written to RAM pages and logged in WAL on disk before being flushed in batches to the data files.
SQL vs NoSQL Difference
- The key difference between SQL and NoSQL databases lies in their front-end APIs and data formats.
- SQL uses tables and rows accessed via structured queries, while NoSQL like MongoDB uses flexible document storage with get/set style API.