# Join Rows
##  Join Rows
### Description
The Join Rows (cartesian product) transform allows you to combine/join multiple input streams ([Cartesian product](https://en.wikipedia.org/wiki/Cartesian_product)) without joining on keys. It works best with one row from each stream. You can add a condition to only join when a condition is met.
| Hop Engine | ✓ |
| ---------- | ------------ |
| Spark | ? |
| Flink | ? |
| Dataflow | ? |
### Options
| Option | Description |
| --------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Transform name | Name of the transform this name has to be unique in a single pipeline. |
| Temp directory | Specify the name of the directory where the system stores temporary files in case you want to combine more then the cached number of rows. |
| TMP-file prefix | This is the prefix of the temporary files that will be generated. |
| Max. cache size | The number of rows to cache before the system reads data from temporary files; required when you want to combine large row sets that do not fit into memory. |
| Main transform to read from | Specifies the transform from which to read most of the data; while the data from other transforms are cached or spooled to disk, the data from this transform is not. |
| The Condition(s) | You can enter a complex condition to limit the number of output row. |
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