Host, Database,system,default layers, Parameters configuration in SAP HANA

 Host layer: it has the highest priority when a parameter is configured in the host layer have more      importance then Database,system,default layers.
Database layer: parameters defined here are specific to tenant database, when a parameter is configured  in the Database layer have more importance then system,default layers.
System layer:parameters defined here are for all tenant databases in one system DB, when a parameter is configured  in the system layer have more importance then default layers.

Default layer: it have least priority among all the 4 parameter layers.