CST 363 Module 5

What does the author mean by a slow index?

What the author means by a 'slow index' is that it refers to a query still running slowly. Basically, a 'slow index' is a situation where an index to look up data in a query runs slowly, even though it should've speed up the performance of the look up, which doesn't happen as expected. 

Why does a slow index happen?

The author goes further on what a 'slow index' is by explaining the reasons behind it. Stating that a 'slow index' happens due to the index lookup involving more than a quick traversal of an index tree. Therefore, the author highlights how the database would need to scan though multiple leaf nodes to find a matching index entry, while fetching the table rows. 

What does this slow index mean overall based on the author?

In the end, the author's overall meaning about a 'slow index' is that the overall process of using the index to find and retrieve data is slow. However, it isn't due to the index itself but due to the extra work required to handle multiple matches and table rows.