Understanding query execution plan operators
If an information object retrieves data from only one data source, the query execution plan consists of a single node: a SQL or ODA node that displays the query sent to the data source. If an information object retrieves data from more than one data source, the query execution plan consists of several nodes, including the following:
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For example, the query execution plan in Figure 3-61 displays two SQL nodes and a join node. The SQL nodes represent the native SQL queries that are sent to two different databases. The join node indicates that the join uses the Nested Loop join algorithm.
Figure 3-61  
You can experiment with different join algorithms and determine which one performs best by doing the following:
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