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Database

Relational algebra, query optimization, storage engines, and database internals.

1. The Relational Model & Relational Algebra

Why flat files fail, how the relational model solved data independence, and the algebra behind every SQL query.

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databaserelational model

2. Modern SQL

Aggregates, GROUP BY, string ops, nested queries, lateral joins, CTEs, and window functions — the SQL features that go beyond basic SELECT.

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databasesql

3. Database Storage (Part I)

How a disk-oriented DBMS organizes files, pages, and tuples on disk — from the storage hierarchy down to slotted pages and word-aligned tuple layouts.

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databasestorage

4. Buffer Pool Manager

How a DBMS manages memory with a buffer pool: replacement policies, why mmap fails, and optimizations like prefetching and scan sharing.

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databasestoragememory