Revert "Calculation of end position of cluster was fixed."

This reverts commit 48cce235809fbfab9eb0f1f2fbe7141c0095388d.
Revert "Json: fixed map management"

This reverts commit 18bc2a730e9e57adc2febacc6606ba5c364868a7.
Fixed case when the schema record is empty: the database is opened and the schema is reset.