CREATE INDEX first_name_idx ON user_data (UPPER(first_name));
WHERE UPPER(first_name) = 'JOHN2';
- Function based index means, creating index based on a function.
- If in search (where clause), frequently any function is used, it's better to create index based on that function.
- Here, in the example, for search, Upper() function is being used. So, it's better to create index using upper function.