# How the parameter pushdown optimization technique works

To set up the parameter pushdown optimization, first set up the optimization, then add the parameter to the transformation step.

![PDI Parameter Pushdown Optimization Workflow](/files/qIU6tM8ZkvRtsJ1QZYWQ)

If you combine this optimization technique with Service Cache optimization and if you query the data service more than once before the cache expires, the query will run against the cached data set if the cached data set contains all of the matching records in the original data set. Also, when you run a test in in the Test Data Service window, then adjust the query and run the test again, the query is not run against the cache. When you run the test, the results only return a certain number of records (100, 500, or 1000, depending on what you selected for **Max Rows**). For more information on the optimization technique, see the **Apply a Service Cache Optimization** section.


---

# Agent Instructions: 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:

```
GET https://docs.pentaho.com/pdia-data-integration/9.3-data-integration/advanced-topics-pentaho-data-integration-overview/pentaho-data-services/optimize-a-pentaho-data-service/apply-a-parameter-pushdown-optimization/how-the-parameter-pushdown-optimization-technique-works.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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.