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

# Wipe and Replace Partitions

> Replace all the rows in a partition

Replaces entire partitions in the target table. Only partitions containing updated data will be overwritten; other partitions will not be modified.

## Parameters

| Parameter                   | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| --------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Partition by                | Defines the partitions of the target table.<ul><li><strong>Databricks</strong>: Each unique value of the partition column corresponds to a partition. You cannot change the granularity of the partitions.</li><li><strong>BigQuery</strong>: You must [manually define the granularity](#define-partition-granularity-bigquery-only) of your partitions. BigQuery does not automatically infer how to write the partitions.</li></ul>                                                                                                                                                                                 |
| (Advanced) On Schema Change | Specifies how schema changes should be handled during the merge process.<ul><li><strong>ignore</strong>: Newly added columns will not be written to the model. This is the default option.</li><li><strong>fail</strong>: Triggers an error message when the source and target schemas diverge.</li><li><strong>append\_new\_columns</strong>: Append new columns to the existing table.</li><li><strong>sync\_all\_columns</strong>: Adds any new columns to the existing table, and removes any columns that are now missing. Includes data type changes. This option uses the output of the previous gem.</li></ul> |

## Example: Replace one day's sales

A sales table is partitioned by the `SALE_DATE` column. A corrected dataset arrives for `2024-01-15`, so only that partition is replaced. All other partitions remain unchanged.

<div class="table-example">
  **Existing target table**

  | ORDER\_ID | PRODUCT | SALE\_DATE |
  | --------- | ------- | ---------- |
  | 101       | Laptop  | 2024-01-14 |
  | 201       | Mouse   | 2024-01-15 |
  | 202       | Monitor | 2024-01-15 |

  **Incoming dataset**

  | ORDER\_ID | PRODUCT  | SALE\_DATE |
  | --------- | -------- | ---------- |
  | 301       | Mouse    | 2024-01-15 |
  | 302       | Keyboard | 2024-01-15 |

  **Resulting target table**

  | ORDER\_ID | PRODUCT  | SALE\_DATE |
  | --------- | -------- | ---------- |
  | 101       | Laptop   | 2024-01-14 |
  | 301       | Mouse    | 2024-01-15 |
  | 302       | Keyboard | 2024-01-15 |

  Because this write mode replaces entire partitions, Prophecy removes all existing rows from any partition represented in the incoming dataset before writing the new rows. Partitions that are not represented in the incoming dataset are left unchanged. In this example, only the `2024-01-15` partition is replaced, while the `2024-01-14` partition remains unchanged.
</div>

## Define partition granularity (BigQuery only)

The following partitioning parameters allow you to define the partition granularity for this operation.

| Parameter                | Description                                                                                                                                                                                                                                                                                     |
| ------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Column Name              | The name of the column used for partitioning the target table.                                                                                                                                                                                                                                  |
| Data Type                | The data type of the partition column. <br />Supported types: `timestamp`, `date`, `datetime`, and `int64`.                                                                                                                                                                                     |
| Partition By granularity | Applicable only to `timestamp`, `date`, or `datetime` data type. <br />Defines the time-based partition granularity: `hour`, `day`, `month`, or `year`.                                                                                                                                         |
| Partition Range          | Applicable only to `int64` data type. <br />Specify a numeric range for partitioning using a **start**, **end**, and **interval** value (e.g., start=`0`, end=`1000`, interval=`10`).<br />You must define an interval value so that Prophecy knows at what intervals to create the partitions. |