Request for Feature: Promote Follower Instance to Primary

[jh244212647]

When the primary instance goes down, I want to switch the follower instance to become the primary. The follower instance has a complete WAL and memtable, which can reduce the switchover time and improve user experience. However, it seems that this feature is not currently supported. Is there any plan to support this in the future?

[jowlyzhang]

By follower instance, do you mean DBImplFollower, or DBImplSecondary.

The former is not following the primary's memtable yet, the latter is trailing the primary's WAL to repopulate its own memtable. But either case, there is no near future plans to support upgrading a DBImplFollower instance or a DBImplSecondary instance to be a full-fledged primary instance.

It's indeed a useful feature.

[jh244212647]

Yes, this is a very useful feature. Ideally, a secondary instance can be upgraded to a primary instance. In a distributed DFS-based system, if the primary node crashes or needs maintenance, the primary node can be switched directly to a secondary instance with a complete memtable. This can reduce the write-off time and improve system availability.