Full Table Scan
A full table scan is a database query operation where the database management system reads every row in a table to find matching records for a query, typically when no suitable index is available or when the query optimizer determines it's more efficient than using an index. It involves sequentially scanning the entire table data, which can be resource-intensive for large tables but is sometimes necessary for operations like bulk data retrieval or when indexes are not applicable. This concept is fundamental in database performance tuning and query optimization across various database systems.
Developers should understand full table scans to optimize database queries and improve application performance, as they can cause slow response times and high I/O usage in production systems. Learning about them is crucial when designing indexes, writing efficient SQL queries, or troubleshooting performance issues in databases like PostgreSQL, MySQL, or Oracle. Use cases include analyzing query execution plans, identifying bottlenecks in data-intensive applications, and making informed decisions about when to create or avoid indexes based on data access patterns.