Auto scaling: A shutdown worker cluster may cause the database to become unreachable

Detail name	Value
Changelog Number	24284
Type	Bug
Status	Resolved
Affected Versions	Exasol 8.29.0
Fix Versions	Exasol 2025.1.0, Exasol 8.29.11
Resolution Date	2025-07-08

Description

When using auto scaling, if a worker cluster which was listed in the auto scaling policy was shutdown or otherwise not active, the entire database may have become unreachable for new connections.

Fix

This issue has been fixed such that a shutdown worker cluster will be ignored for the session-autobalance and session-round-robin policies.

When using the {{session-weighted}}policy, multiple attempts will be made to select an active cluster; however since this policy is probabilistic, it can happen that a connection attempt could fail even after trying multiple times. In this case, the client can simply try to connect again.

Workaround

Any shutdown worker clusters should be removed from the auto scaling policy.