CST 363 Week 5 Report

Generally speaking, an index provides faster read times for queries in SQL. There are three elements that, when combined, can prove an index search to be slower than expected, however. The first regards the leaf node chain. The second is accessing the table. If the hits point to many table blocks, that is a bad sign for performance. The third is fetching the relevant data from table(s). Databases can actually be asked how they use an index. In the oracle database, which has three operations for describing an index lookup, the index range scan, which performs the tree traversal and follows the leaf node chain to find matching entries, is the default fallback operation if multiple potential entries are triggered. It is precisely in this scenario where a "slow index" can manifest.