- The DBMS determines the page on secondary storage that contains the required record
using indexes or table scans, as appropriate (see Section 21.4). The DBMS then reads
that page from secondary storage and copies it into its cache.
- The DBMS subsequently transfers the required parts of the record from the cache into
the application’s memory space. Conversions may be necessary to convert the SQL data
types into the application’s data types.
- The application can then update the record’s fields in its own memory space.
- The application transfers the modified fields back to the DBMS cache using SQL, again
requiring conversions between data types.
- Finally, at an appropriate point the DBMS writes the updated page of the cache back to
secondary storage.