面试题与答案

Isolation level determines the degree to which one transaction must be isolated from resource changes made by other transactions.

The EXPLAIN statement is used to analyze and optimize SQL queries by providing information about the access path chosen by the DB2 optimizer.

DB2 uses various concurrency control mechanisms, including locks and isolation levels, to ensure that transactions execute without interference from other transactions.

Performance can be improved by creating indexes, optimizing SQL queries, updating statistics, and using proper join and filter conditions.

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.

The db2diag.log file contains diagnostic information about the database manager and its associated processes. It is used for troubleshooting and monitoring.

Locking can be monitored using tools like db2pd and improved by using proper isolation levels, avoiding long-running transactions, and optimizing SQL queries.

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.

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.

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.

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.