The difference between count (1) and COUNT (*) in Oracle

2. Ount (1) compared to count (*):
4. If your data table does not have a primary key, then count (1) is faster than COUNT (*)
6. If there is a primary key, then the primary key (the Federated primary key) as the count condition is also faster than COUNT (*)
8. If your table has only one field, then count (*) is the quickest.
10. COUNT (*) count (1) compares the two.   The data field that corresponds to count (1) is mostly still.
12. If count (1) is a clustered index, ID, that must be count (1) fast.   But the difference is very small.
14. Because count (*), automatically optimizes the specified field to that one. So there is no need to count (?), with count (*), SQL will help you to complete the optimized
18. Count Detailed:
    
20. COUNT (*) returns the total number of rows that exist in the table, including rows with a value of null, whereas count (column name) returns the total number of all rows except null in the table (columns with default values will also be counted).
22. Distinct the column name, the result will be the result of dropping the value null and repeating the data
    

The difference between count (1) and COUNT (*) in Oracle