August 2002
Intermediate to advanced
528 pages
10h 12m
English
When the SQL statement contains a join condition, the optimizer must decide which method to use in order to combine the retrieved records. There are several available methods. Each of the methods is better in a certain situation. Normally Oracle will choose the proper join operation. However, algorithms are not always perfect. It may be necessary to change the selected join type using a hint. The following sections will describe the various join types.
In a nested-loop join, Oracle identifies target records in one table, called the driving table, and then locates corresponding records in a second table, called the inner table. Oracle generally uses an index to identify records in the driving table and scans ...