CST 363 Weekly Journal #5

 If indexes are supposed to speed up performance of query,  what does the author mean by a slow index? 

- What the author means by a slow index is when an index lookup is run, this will lead to multiple matching entries in the leaf nodes. This can cause the leaf node chain to slow down the index lookup process. Furthermore, to find a match in the index, the database must perform some I/O operations to get the table data for each of the matching entries. Consequently, it means that for each hit found in the index, there is a table access, which involves reading from various table blocks and can also slow down the query if there are many hits within them.