Amazon Database Administrator DBA Interview Questions and Answers

Different types of explain plans include basic, serial, parallel, and statement-level.

• Basic explain plan shows the execution plan of a SQL statement

• Serial explain plan shows the execution plan for a serial query

• Parallel explain plan shows the execution plan for a parallel query

• Statement-level explain plan shows the execution plan for each SQL statement in a PL/SQL block

MVCC stands for Multi-Version Concurrency Control, a technique used in database management systems to allow multiple transactions to access the same data simultaneously.

• MVCC is used to maintain data consistency and prevent conflicts between transactions.

• It works by creating multiple versions of a data item, each with a timestamp indicating when it was created.

• When a transaction reads a data item, it sees the version wi...read more