IBM DB2 Interview Questions and Answers
Experienced / Expert level questions & answers
Ques 1. How does isolation level affect database transactions in DB2?
Isolation level determines the degree to which one transaction must be isolated from resource changes made by other transactions.
Ques 2. What is the purpose of the EXPLAIN statement in DB2?
The EXPLAIN statement is used to analyze and optimize SQL queries by providing information about the access path chosen by the DB2 optimizer.
Ques 3. How does DB2 handle concurrency control in a multi-user environment?
DB2 uses various concurrency control mechanisms, including locks and isolation levels, to ensure that transactions execute without interference from other transactions.
Ques 4. How can you improve the performance of a DB2 query?
Performance can be improved by creating indexes, optimizing SQL queries, updating statistics, and using proper join and filter conditions.
Ques 5. What is a DB2 index and how does it improve query performance?
An index is a data structure that provides a quick and efficient way to look up and access data in a table. It improves query performance by reducing the number of rows that need to be scanned.
Ques 6. Explain the purpose of the db2diag.log file in DB2.
The db2diag.log file contains diagnostic information about the database manager and its associated processes. It is used for troubleshooting and monitoring.
Ques 7. How can you monitor and optimize locking in DB2?
Locking can be monitored using tools like db2pd and improved by using proper isolation levels, avoiding long-running transactions, and optimizing SQL queries.
Ques 8. What is a data partitioning feature in DB2?
Data partitioning is a feature in DB2 that allows tables and indexes to be divided into smaller, more manageable pieces, improving query performance and parallelism.
Ques 9. What is the purpose of the db2dart utility in DB2?
The db2dart utility is used for database analysis and recovery. It can be used to check the consistency of database objects and repair certain types of corruption.
Ques 10. How can you monitor and manage database performance in DB2?
Database performance can be monitored using tools like db2top and db2mon. Performance can be managed by optimizing SQL queries, updating statistics, and configuring buffer pools.
Ques 11. What is the purpose of the db2relocatedb command in DB2?
The db2relocatedb command is used to move a database from one directory path to another. It helps in relocating databases without requiring a full backup and restore.
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