Master Coding Skills &
System Design.

Fix slow MySQL queries — enable slow query log, read every EXPLAIN field, identify full table scans, filesorts, and apply targeted fixes.

Master PHP 8.x type system — union types, enums with methods, named arguments to skip optional parameters, and intersection types.

Design a video streaming service for 238M subscribers — transcoding pipeline, adaptive bitrate HLS, CDN architecture, and segment caching.

Master JavaScript generators — function*, yield, yield*, two-way communication, infinite sequences, and custom iterators with Symbol.iterator.

Master Python heapq — min-heap, max-heap simulation, Top K elements pattern, merge K sorted arrays, and Dijkstra with priority queue.

Master SQL Common Table Expressions — single and multiple CTEs, recursive CTEs for hierarchies, and running totals with CTEs.

Understand PHP Fibers — cooperative multitasking, how Fibers differ from generators and threads, and how async PHP frameworks use them.

Master JavaScript Symbol for unique keys, WeakMap for memory-safe caching, and WeakRef for holding objects without preventing garbage collection.

Master graph algorithms — BFS for shortest unweighted path, DFS for traversal, Dijkstra for weighted shortest path, topological sort for DAGs.