> For the complete documentation index, see [llms.txt](https://docs.pentaho.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview/merge-rows-diff/select-an-engine-merge-rows-diff/using-merge-rows-diff-on-pentaho-engine.md). # Using Merge rows (diff) on the Pentaho engine If you are running your transformation on the Pentaho engine, use the following instructions to set up the Merge rows (diff) step. **Important:** When using the Pentaho transformation engine, the reference rows and compare rows must be sorted on the specified keys. When using the Merge rows (diff) step within a PDI transformation, such as with the [Sort rows](https://github.com/pentaho/documentation/blob/main/PDIA/9.3/PDI/Transformation%20steps/PDI%20transformation%20steps%20reference%20\(overview\)/Sort%20rows%20\(transformation%20step\)=GUID-DE76988A-FFA1-4B13-9F4D-8C357068552A=2=en=.md) step, sorting works correctly. However, if the data is sorted outside of PDI, such as in a SQL query, you may run into issues with the internal case sensitive/insensitive flag or other collations. If you are using the Merge rows (diff) step with the Spark engine, see [Using Merge rows (diff) on the Spark engine](/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview/merge-rows-diff/select-an-engine-merge-rows-diff/using-merge-rows-diff-on-spark-engine-article.md). --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/pdi-transformation-steps-reference-overview/merge-rows-diff/select-an-engine-merge-rows-diff/using-merge-rows-diff-on-pentaho-engine.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.