DB2 Log Retention Settings and Recommendations Note from the Data Whisperer
By Tom Nonmacher
DB2 Log Retention settings are an integral part of database management and optimization in SQL Server 2019, MySQL 8.0, DB2 11.5, Azure SQL, and Azure Synapse. They provide a mechanism to control the volume of logs retained, thus directly influencing the amount of disk space consumed. This blog post will delve into best practices and recommendations for configuring DB2 Log Retention settings.
In the world of databases, logs serve as a critical element in recoverability and troubleshooting. When a database operation occurs, the details are recorded in the log files, providing a chronological record of all changes and transactions. However, without proper management, these log files can grow exponentially leading to disk space issues. This is where log retention settings come into play.
In DB2, the LOGRETAIN and USEREXIT database configuration parameters control the behavior of active and archive logging. Active logs hold data that's yet to be committed, while archive logs store committed transactions. To enable archive logging, set LOGRETAIN to RECOVERY and USEREXIT to ON.
-- DB2 code
UPDATE DATABASE CONFIGURATION FOR sample USING LOGRETAIN RECOVERY;
UPDATE DATABASE CONFIGURATION FOR sample USING USEREXIT ON;
When using SQL Server 2019 or Azure SQL, the recovery model of the database influences log retention. The FULL recovery model retains all logs, providing point-in-time restore capability, but at the cost of potential disk space issues. The SIMPLE recovery model, on the other hand, automatically reclaims log space to keep space requirements small, at the expense of point-in-time recovery.
In MySQL 8.0, the expire_logs_days system variable determines the number of days binary log files are retained. Binary logs record changes to the database, and their retention is crucial for backup and replication tasks.
-- MySQL code
SET GLOBAL expire_logs_days = 14;
For Azure Synapse, the retention period for logs is determined by the Backup Retention Period setting, which can range from 7 to 35 days.
In conclusion, log retention settings are a crucial aspect of database management across all platforms, including DB2, SQL Server, MySQL, Azure SQL, and Azure Synapse. They should be configured with a keen eye on the balance between disk space utilization and the ability to recover data. This balance hinges on understanding the nature of your data, the frequency of transactions, and the business requirement for data recovery.