Oracle Database - Join Order


To execute a statement that joins more than two tables, Oracle joins two of the tables and then joins the resulting row source to the next table. This process is continued until all tables are joined into the result.

A join order is the order in which different join items, such as tables, are accessed and joined together.


For example, in a join order of table1, table2, and table3, table table1 is accessed first. Next, table2 is accessed, and its data is joined to table1 data to produce a join of table1 and table2. Finally, table3 is accessed, and its data is joined to the result of the join between table1 and table2.

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