# Migrate from Data-Add to Data-Correction Schema

This guide explains how to migrate an existing schema built with the **Data-Add** module to one using the **Data-Correction** module in WriteBackExtreme. The goal is to shift from a many-to-many mapping model to a precise one-to-one model for better control, traceability, and data integrity.

***

### Background: Module Differences

**Data-Add Module**:

* Uses a **many-to-many** relationship.
* Stores mapping records in the `_mapping` table in the repository.
* Every new datapoint written creates a new row.

**Data-Correction Module**:

* Uses a **one-to-one** relationship.
* Data is written directly into the schema table.
* Enables inline editing and record replacement.

***

### Why Migrate?

| Benefit             | Description                                                         |
| ------------------- | ------------------------------------------------------------------- |
| Data Integrity      | Prevents duplicates by updating existing records.                   |
| Traceability        | Maps each entry directly to a Tableau datapoint using a unique key. |
| Simplified Workflow | Removes complexity by eliminating mapping logic for updates.        |

***

### Migration Overview

1. **Create a new schema** using the **Data-Correction** module.
2. **Include all original fields** from the Data-Add schema.
3. **Add one new column**: `mapping_key` — a unique identifier for Tableau datapoint.
4. **Export existing data** from the Data-Add schema.
5. **Modify the data**: Add a `mapping_key` column in Excel or CSV.
6. **Import modified data** into the new Data-Correction schema.
7. **Update Tableau** to use the `mapping_key` for correction mapping.

### Step-by-Step Instructions

#### 1. Create a New Schema

* In the Management Console, create a new schema.
* Select the **Data-Correction** module.
* **Do not base it on the existing Data-Add schema**.

#### 2. Add Fields

* Recreate all fields from the original Data-Add schema.
* Add a new column:
  * `mapping_key` (type: String)
  * This will serve as the primary link to Tableau datapoints.

#### 3. Export Existing Data

* Use the extension to export existing data from the Data-Add schema.
* Alternatively, request a database export from your DBA.

#### 4. Add `mapping_key` to Your Data

* In Excel/CSV, create a `mapping_key` column.
* Populate it using a logic that combines one or more fields that identify the Tableau record.

**Example:**

If you have:

```
product_id = "ABC123"
country = "US"
```

Create:

```
mapping_key = "ABC123_US"
```

Use a Tableau calculated field that generates the same key.

#### 5. Import into Data-Correction Schema

* Upload the modified data with the `mapping_key` column.
* Verify all required fields match.

#### 6. Link Tableau to the New Schema

* In Tableau, ensure your dataset includes the same calculated field `mapping_key`.
* Use it as the **identifier field** when configuring the extension.

***

###  Field Mapping Example:

#### Original Data-Add Schema (`dataadd_product_pricing_for_countries`):

| Field | Type    |
| ----- | ------- |
| id    | UUID    |
| price | Decimal |

#### New Data-Correction Schema (`datacorrect_product_pricing_for_countries`):

| Field        | Type    |
| ------------ | ------- |
| id           | UUID    |
| mapping\_key | String  |
| price        | Decimal |

***

### Important Notes

* `mapping_key` must be **uniquely reproducible** in Tableau and your schema.
* Use **calculated fields** to generate the same value on both sides.
* Be sure the new schema is tested in a staging dashboard before replacing production dashboards.

***

For questions or help, contact **<support@appsfortableau.com>**.


---

# 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.infotopics.com/writebackextreme/features/management-console/schemas/migrate-from-data-add-to-data-correction-schema.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.