Programming Impact DS0-001 Practice Questions (Page 3)

Questions 11–15

1. 11foundation · easy

   In Entity Framework, what is the purpose of the DbContext class?

   • AIt executes raw SQL queries without using LINQ
   • BIt generates the database tables automatically without any configuration
   • CIt defines the database schema using C# attributes
   • DIt represents a session with the database and manages entity objects
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2. 12foundation · easy

   What is the primary purpose of an Object-Relational Mapping (ORM) tool?

   • ATo generate database schemas automatically without any developer input
   • BTo replace the need for a relational database by storing objects directly
   • CTo optimize SQL queries by rewriting them at runtime
   • DTo translate between object-oriented code and relational database structures
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4. 13expert · hard

   A Hibernate-based application is running a batch job that inserts 100,000 records into a table. The job is slow and the database server's transaction log is growing rapidly. The DBA notices that each insert is committed individually. Which Hibernate configuration change would most effectively improve the performance of this batch insert?

   • AUse `session.clear()` after each insert to free memory.
   • BSet `hibernate.jdbc.batch_size` to a value like 50 and use a transaction that commits at the end.
   • CEnable the second-level cache for the entity being inserted.
   • DChange the entity's ID generation strategy to `IDENTITY`.
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5. 14application · medium

   A Java developer is using Hibernate with a `Session` object. The developer needs to ensure that changes made to a persistent object are saved to the database. Which method should be called to synchronize the state of the session with the database?

   • A`session.close()`
   • B`session.flush()`
   • C`session.save()`
   • D`session.update()`
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6. 15expert · hard

   A database administrator is validating a SQL query that uses a `UNION` to combine results from two large tables. The query is slow. The DBA notices that the `UNION` is causing a sort operation to remove duplicates. The DBA knows that the two result sets are already distinct. Which change would improve performance?

   • AChange `UNION` to `UNION ALL`.
   • BUse `EXCEPT` instead of `UNION`.
   • CIncrease the server's memory to speed up the sort.
   • DAdd an index on the columns in the `WHERE` clause of each SELECT.
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