Indexing depends upon the queries in the application.
There is no one-size-fits-all break-even point for indexed versus table scan access. If only a few rows are being accessed, the index will be preferred.
If almost all the rows are being accessed, the full table scan will be preferred. In between these two extremes, your “mileage” will vary.
A concatenated index is more useful if it also supports queries where not all columns are specified. For instance SURNAME, FIRSTNAME is more useful than FIRSTNAME, SURNAME because queries against SURNAME only are more likely to occur than queries against FIRSTNAME only.
Global indexes provide better performance for queries that must span all partitions.
There is no one-size-fits-all break-even point for indexed versus table scan access. If only a few rows are being accessed, the index will be preferred.
If almost all the rows are being accessed, the full table scan will be preferred. In between these two extremes, your “mileage” will vary.
A concatenated index is more useful if it also supports queries where not all columns are specified. For instance SURNAME, FIRSTNAME is more useful than FIRSTNAME, SURNAME because queries against SURNAME only are more likely to occur than queries against FIRSTNAME only.
Global indexes provide better performance for queries that must span all partitions.