These are LLD questions of the kind Oracle actually asks — the patterns reported from Oracle's AI-engineering rounds, where design trade-offs, scale and failure modes matter as much as definitions. Treat this page as a mock interview: say every answer out loud before revealing it. If one surprises you, the lesson behind it is linked at the bottom.
Oracle LLD concept questions
Oracle's LLD rounds (often database-tooling flavoured) sometimes ask: design a database connection pool that reuses a fixed number of connections across many requests.
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Two threads call acquire() on the connection pool above at the same instant, and only one connection is left free. What must the design guarantee?
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A query-building tool needs to support several database dialects (Oracle SQL, MySQL, PostgreSQL) generating slightly different SQL syntax for the same logical query. What pattern fits?
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How to use this page: Oracle rarely asks something you've never seen — they ask a standard LLD concept and then push one level deeper ("why?", "what would you do if..."). Master the concept in the LLD course lessons, and the follow-up stops being scary.
Keep practising: SOLID Principles, Strategy Pattern, Design a Parking Lot and UML Diagrams cover what most Oracle LLD rounds test.