This survey presents a comprehensive overview of top-k query processing techniques in relational database systems. It classifies these techniques based on five key design dimensions: query model, data access methods, implementation level, data and query uncertainty, and ranking function. The survey discusses various techniques, including top-k selection, join, and aggregate queries, and explores how different assumptions about data access (sorted, random, or a combination) affect the design of these techniques. It also addresses the impact of uncertainty in data and queries, and the role of monotonicity in ranking functions. The survey highlights the importance of efficient top-k processing in applications such as web search, multimedia retrieval, and distributed systems. It also discusses the integration of top-k processing into relational databases, including techniques like the Threshold Algorithm (TA), No Random Access (NRA), and Stream-Combine. The survey concludes with a discussion of future research directions in this area.This survey presents a comprehensive overview of top-k query processing techniques in relational database systems. It classifies these techniques based on five key design dimensions: query model, data access methods, implementation level, data and query uncertainty, and ranking function. The survey discusses various techniques, including top-k selection, join, and aggregate queries, and explores how different assumptions about data access (sorted, random, or a combination) affect the design of these techniques. It also addresses the impact of uncertainty in data and queries, and the role of monotonicity in ranking functions. The survey highlights the importance of efficient top-k processing in applications such as web search, multimedia retrieval, and distributed systems. It also discusses the integration of top-k processing into relational databases, including techniques like the Threshold Algorithm (TA), No Random Access (NRA), and Stream-Combine. The survey concludes with a discussion of future research directions in this area.