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The use of a merge join Cartesian is very expensive for Oracle. Cartesian joins can be caused by a missing Table Join condition to the WHERE clause.
A Cartesian Join is used when one or more of the tables does not have any join conditions to any other tables in the statement. The optimizer joins every row from one data source with every row from the other data source, creating the Cartesian product of the two sets.
| Cartesian Join Used |
| Description | |
| What to do next | Examine the predicates in the statement’s WHERE clause. |
| Advice | To avoid a Cartesian Join make sure that you have provided the proper join conditions in the statement’s WHERE clause. |
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