The following table shows some of the common join operations you may encounter while using the Explain SQL window.
| Operation | Option | Description |
|---|---|---|
|
CONNECT BY |
A hierarchical self-join is performed on the output of the preceding steps. | |
|
MERGE JOIN |
A merge join is performed on the output of the preceding steps. | |
|
MERGE JOIN |
OUTER |
An outer join is implemented by a merge join. |
|
NESTED LOOPS |
A Nested Loops join is performed on the preceding steps. For each row in the upper result set, the lower result set is scanned to find a matching row. | |
|
MERGE JOIN |
SEMI |
Denotes a sort-merge semi-join. |
|
HASH JOIN |
SEMI |
Denotes a hash semi-join. |
|
MERGE JOIN |
ANTI |
Denotes a hash anti-join. |
|
NESTED LOOPS |
OUTER |
An outer join is implemented by a nested loop join. |
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