> ## 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.

# Append Unique Rows

> Insert only new records, leaving matching records unchanged

When you choose the **Append Unique Rows** option, if a row's unique key already exists in the target table, the incoming row is ignored and the existing row is left unchanged. Only rows with a unique key that doesn't yet exist in the target are inserted.

<Note>
  Unlike [Upsert Row](/data-analysis/gems/source-target/table/write/upsert), this mode never
  modifies existing records; it only inserts new ones.
</Note>

## Parameters

| Parameter                                          | Description                                                                                                                                          |
| -------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------- |
| Unique Key                                         | Column(s) used to find records that already exist in the target table. Matching records are left unchanged; only the remaining records are inserted. |
| Use Predicate                                      | Limits which target rows are checked for duplicates. Keys outside the predicate range may be re-inserted.                                            |
| Use a condition to filter data or incremental runs | Enables applying conditions for filtering the incoming data into the table.                                                                          |

<Note>
  Merge Columns, Exclude Columns, and On Schema Change don't apply to this write mode. If you
  switch to Append Unique Rows from another merge approach, any values set for those options are
  cleared.
</Note>

## Example: Append new orders only

An order table uses `ORDER_ID` as the unique key. The incoming dataset includes a status update for an existing order and one new order.

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

  | ORDER\_ID | STATUS  | AMOUNT |
  | --------- | ------- | ------ |
  | 101       | Shipped | 250    |
  | 102       | Pending | 100    |

  ### Incoming dataset

  | ORDER\_ID | STATUS    | AMOUNT |
  | --------- | --------- | ------ |
  | 101       | Cancelled | 250    |
  | 103       | Pending   | 75     |

  ### Resulting target table

  | ORDER\_ID | STATUS  | AMOUNT |
  | --------- | ------- | ------ |
  | 101       | Shipped | 250    |
  | 102       | Pending | 100    |
  | 103       | Pending | 75     |

  Because `ORDER_ID` `101` already exists in the target table, its incoming row is ignored, so the existing `Shipped` status is left unchanged.

  `ORDER_ID` `103` doesn't exist in the target, so it's inserted as a new row.

  `ORDER_ID` `102` has no matching row in the incoming dataset, so it's left as-is.
</div>