Estimate index size and the write cost each index adds.
Index size follows from key width and fill factor. Each additional index multiplies write cost, because every insert or update must maintain all of them. Unused indexes cost storage and write throughput while delivering nothing, which makes auditing them one of the highest-value database tasks.
Index Size
Index size = ⌈rows ÷ entries per page⌉ × page size, where entries per page depends on fill factor
Index size = ⌈rows ÷ entries per page⌉ × page size, where entries per page depends on fill factor Index size follows from key width and fill factor. Each additional index multiplies write cost, because every insert or update must maintain all of them.
Unused indexes cost storage and write throughput while delivering nothing, which makes auditing them one of the highest-value database tasks.
This calculator takes 5 inputs: Rows indexed, Indexed key size, Row pointer size, Page fill factor, Number of such indexes. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.