Understanding backup-related Waits happening to PostgreSQL

In PostgreSQL, backup-related waits refer to the wait events that occur when performing database backups using tools like pg_dump or pg_basebackup. These waits are typically associated with I/O operations, as the backup process involves reading data from disk and writing it to the backup destination. Understanding these waits can help you optimize your backup process and minimize potential bottlenecks. Here are a few common backup-related waits and their implications:

1. backup_wait_io: This wait event occurs when the backup process is waiting for I/O operations to complete. It indicates that the backup process is constrained by disk I/O performance. To mitigate this, consider optimizing your disk subsystem, using faster storage devices, or adjusting the backup configuration to minimize I/O operations.

2. backup_wait_lock: This wait event occurs when the backup process is waiting for locks on certain database objects. It can happen if there are concurrent transactions or long-running queries holding locks. To reduce this wait, ensure that your backup process is not conflicting with other database activity, such as by scheduling backups during low-usage periods or using locking mechanisms that are compatible with concurrent activity.

3. backup_wait_timeout: This wait event occurs when the backup process reaches the configured timeout limit. It indicates that the backup process took longer than expected, potentially due to high data volume or slow I/O. You can adjust the timeout settings based on your backup requirements and system performance.

4. backup_wait_relation: This wait event occurs when the backup process is waiting for a specific relation or table to become available. It can happen if there are concurrent schema changes or transactions modifying the table being backed up. Consider coordinating schema changes and backup operations to minimize conflicts and avoid this wait event.

To get more insights into backup-related waits, you can monitor the PostgreSQL system views such as pg_stat_activity, pg_stat_progress_basebackup, and pg_stat_progress_dump to track the progress and performance of ongoing backup operations. Analyzing these waits and optimizing your backup process accordingly can help ensure efficient and reliable backups in PostgreSQL.

About Shiv Iyer 452 Articles
Open Source Database Systems Engineer with a deep understanding of Optimizer Internals, Performance Engineering, Scalability and Data SRE. Shiv currently is the Founder, Investor, Board Member and CEO of multiple Database Systems Infrastructure Operations companies in the Transaction Processing Computing and ColumnStores ecosystem. He is also a frequent speaker in open source software conferences globally.