Vacuum and WAL Files Creation
This document explains the impact of PostgreSQL's VACUUM
command on disk space and how to prevent its usage from
triggering the a9s Parachute.
PostgreSQL's VACUUM
command is used to reclaim storage occupied
by dead tuples. To achieve this, the VACUUM
command can trigger the following operations:
- Delete old row versions
- Freeze rows
- Truncate empty pages at the end of the table
These operations generate changes that are logged in Write-Ahead Logging (WAL) files. Thus, executing VACUUM
on large
or frequently updated tables can significantly increase the number of WAL files, consuming a lot of disk space.
Since PostgreSQL retains these files for performance and recovery purposes, this can quickly reduce available disk space
and potentially trigger the a9s Parachute. For more details, see a9s Parachute Concerns.
Prevention Strategies
To avoid triggering the a9s Parachute due to high disk usage:
- Increase Persistent Disk Size: Ensure sufficient disk space before executing
VACUUM
. - Monitor Disk Usage: Regularly check disk space to prevent unexpected issues.
For more information on disk usage, refer to a9s PostgreSQL Resources Considerations - Disk Space.