Apama Documentation : Developing Apama Applications : Developing Apama Applications in EPL : Working with Streams and Stream Queries : Troubleshooting and stream query coding guidelines : Prefer equi-joins to cross-joins
Prefer equi-joins to cross-joins
In a query using an equi-join, the items from the two input sets are joined based on equality of key values. The identification of matching items is very efficient.
Cross-joins have no expressions, so it is more efficient to calculate them than equi-joins. However, cross-joins are less preferable to equi-joins if they produce unwanted items that must subsequently be filtered out.
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