@StephanHaarmann Is there a way to see the C8 DB schema details of execution, ACT, RE,HI, Deployment and variables?
Since we can see the DB scheme details in C7 right?
No, there is no relational database in Camunda 8.
Data is exported to Elasticsearch, you can peek into the indices to see the schema - however, the schema differs per App (Optimize/Operate/Tasklist)
ohh 
do we have any example for this? data will be automatically exported to Elasticsearch or have to do and how to do??
You can only access Elasticsearch in Self-Managed Camunda 8. In SaaS, you cannot access Elasticsearch directly and would need to extract the required information via one of the APIs.
If you deployed Camunda 8 Using the Helm Charts, the Elasticsearch exporter is activated automatically.
You can use Elasticsearches REST API to get and inspect all indices.
What are you planning to do with this data? Maybe there is an alternative.
I want to analyze or patch the process variable in case of failure, also can help during migration to analyze the data before migration and reconciling the data for report.
You have given me Elasticsearch docs and tutorial details. I am looking how can we use this Elasticsearch with C8 to export the data.
You can also write your own exporter: