Multi-level Indices
Indices themselves may become too large for efficient processing.
Example:
- Consider file with 100000 records with 10 records in a block.
- With sparse index and one index per block we have about 10,000 indices.
- Assuming 100 indices fit into a block we need about 100 blocks.
- It is desirable to keep the index file in the main memory.
- Problem: Searching a large index file becomes expensive.