Database Cursors: Row-by-Row Result Processing

A database cursor is an iterator for a query's results, letting you process a large dataset one row at a time instead of loading everything into application memory. This is essential for batch jobs that need to perform complex logic on millions of records without causing an out-of-memory error. The main footgun is performance: cursors are almost always slower than set-based SQL operations and can hold locks for extended periods, which harms database concurrency.