# Which Problems Are Solved
Scheduled handlers use `eventstore.InstanceIDs` to get the all active
instances within a given timeframe. This function scrapes through all
events written within that time frame which can cause heavy load on the
database.
# How the Problems Are Solved
A new query cache `activeInstances` is introduced which caches the ids
of all instances queried by id or host within the configured timeframe.
# Additional Changes
- Changed `default.yaml`
- Removed `HandleActiveInstances` from custom handler configs
- Added `MaxActiveInstances` to define the maximal amount of cached
instance ids
- fixed start-from-init and start-from-setup to start auth and admin
projections twice
- fixed org cache invalidation to use correct index
# Additional Context
- part of #8999
# Which Problems Are Solved
Instance domains are only computed on read side. This can cause missing
domains if calls are executed shortly after a instance domain (or
instance) was added.
# How the Problems Are Solved
The instance domain is added to the fields table which is filled on
command side.
# Additional Changes
- added setup step to compute instance domains
- instance by host uses fields table instead of instance_domains table
# Additional Context
- part of https://github.com/zitadel/zitadel/issues/8999
