Whenever SAP system is restarted, data is fetched from database and later it is kept in the buffer cache.
Every screen in SAP has the screen number and when anything is queried, dialog work process tries to search the database for screen and then returns the value/screen.
This process is recorded in the temporary memory called ‘Buffer’.
Next time when we try to get the same screen –> SQL query is passed and if the information is present in buffer, it will reuse it instead of fetching it from DB. This is called as Hit
If the data is not present in Database Buffer Cache, it will be a ‘Miss/Fail’ and system has to pull the data from database.
So Hit Ratio is generally the ratio between data retrieval from Database buffer cache and database.
Usually Hit ratio more than 95% is considered as a sign of healthy system.
Excellent Hit Ratio:
Buffered objects can be searched via ST02:
