Data coherency between trusted DBMS and untrusted DBMS

A method for processing data in a database engine, the method comprising:

• storing, by the database engine, a first instance of a first table in plaintext on a first storage device of a first computer system;
• maintaining encryption information about encryption methods and encryption keys of at least one predefined column of the first table;
• creating encrypted data on the first storage device based on the encryption methods and encryption keys of the at least one predefined column of the first table by creating a temporary table, encrypting data of the first table resulting in the encrypted data, and storing the encrypted data in the temporary table;
• loading the encrypted data of the temporary table into a second instance of the first table on a second storage device of a second computer system using a further database engine, and deleting the temporary table after the loading of the encrypted data;
• in response to data changes in the column, writing first log entries for the data changes in plaintext to the first storage device;
• encrypting the data changes by an encryption component using the encryption information, resulting in creation of encrypted data changes in the temporary table;
• and
• writing second log entries for the encrypted data changes and applying the encrypted data changes to the second instance of the first table based on the temporary table.