---
title: "Use Roll Forward Logic"
slug: "use-roll-forward-logic"
updated: 2024-09-10T10:07:06Z
published: 2024-09-10T10:07:06Z
canonical: "help.mozenda.com/use-roll-forward-logic"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.mozenda.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Use Roll Forward Logic

When Roll Forward logic is enabled and unique fields are set during harvesting, Mozenda will overwrite empty values in non-unique fields with the most recently captured non-empty values. If Store Item History is enabled, this feature will also look back to the most recent previous run for the matching unique row and pull non-empty values forward.

For example, given the following rows of data (where ID is the unique field):

| Created | ItemID | ID | Full Name | Sex | Occupation |
| --- | --- | --- | --- | --- | --- |
| 2019-12-20 00:01:22 | 1001 | 1234 | John Smith | M | - |
| 2019-12-20 01:00:12 | 1002 | 1234 | John Smith | - | Explorer |
| 2019-12-20 01:30:54 | 1003 | 1234 | John Smith | - | - |

With Roll Forward logic activated during harvesting, they would be combined into:

| Created | ItemID | ID | Full Name | Sex | Occupation |
| --- | --- | --- | --- | --- | --- |
| 2019-12-20 00:01:22 | 1001 | 1234 | John Smith | M | Explorer |

Without Roll Forward logic activated during harvesting, they would be combined into:

| Created | ItemID | ID | Full Name | Sex | Occupation |
| --- | --- | --- | --- | --- | --- |
| 2019-12-20 00:01:22 | 1001 | 1234 | John Smith | - | - |

          Note

          

Roll Forward logic can't be applied to previous or active runs. Make sure to apply Roll Forward logic before you schedule or manually run your agent(s).