Change Data Source

Use Change data source to replace the primary data source of an existing sheet.

Use this feature when you want to:

• switch the sheet to a source with the same structure

• replace the source with one that has fewer columns

• replace the source with one that has additional columns

1. Before you start

• The feature is available from the Model tab.

• It is not available for multi-sheets.

• The current data source is shown for reference, but it does not appear in the replacement list.

• You can switch to a source with fewer, the same number of, or more columns than the current source.

You can use this feature even if the sheet already contains charts, pivot tables, grouping, filters, formulas, lookup columns, or mapped columns.

This article uses the following example files:

• 01_base_sheet_source.csv — the original source

• 02_target_fewer_columns.csv — a compatible replacement source with fewer columns

• 03_target_auto_match_plus_3.csv — a compatible replacement source with additional columns

2. Open the dialog

1. Open the sheet.

2. Go to Model.

3. Click Change data source.

KAWA opens a 4-step flow:

1. Select source

2. Map columns

3. New columns

4. Review

3. Step 1 — Select source

Choose the new data source for the sheet.

For each available source, KAWA shows:

• the source name

• the number of columns

• the difference compared with the current source

Badges show the column-count difference:

• +N extra — the new source has more columns

• N fewer — the new source has fewer columns

3.1 Example

Suppose the sheet currently uses 01_base_sheet_source.csv.

In the source list, you may see:

• 02_target_fewer_columns.csv with 2 fewer

• 03_target_auto_match_plus_3.csv with 3 extra

This tells you that one replacement will leave some existing columns without data, while the other may let you add new columns to the sheet.

Click Next to continue.

4. Step 2 — Map columns

KAWA matches columns from the current sheet to columns in the new data source.

KAWA automatically matches columns when their name and type are compatible. Review these matches before continuing.

4.1 Current source columns

This section shows columns that are currently mapped from the active primary source.

Rules:

• Key columns must remain mapped.

• Non-key columns can be left unmapped.

• Columns with incompatible types cannot be mapped to each other.

• One target column can be used only once.

• Mapping must remain 1:1.

If a non-key column is left unmapped, it stays in the sheet but no longer receives data from the new source.

4.2 Example: replace with fewer columns

Suppose 01_base_sheet_source.csv contains these columns:

• record id

• account_id

• country

• city

• segment

• signup_date

• order_count

• lifetime_value

• last_order_date

Now replace it with 02_target_fewer_columns.csv, which contains:

• record id

• account_id

• country

• city

• signup_date

• order_count

• lifetime_value

In this case, KAWA automatically matches 7 columns and leaves these columns unmapped:

• segment

• last_order_date

These two columns remain in the sheet, but they will no longer receive data after the change.

4.3 Previously unmapped columns

If the sheet already contains columns that lost their source mapping during an earlier replacement, KAWA shows them in a separate Previously unmapped columns section.

Use this section to reconnect those columns to the new source.

Important behavior:

• KAWA can auto-match these columns when possible.

• These columns are optional to remap.

• A target column from the new source can be used only once across the entire mapping step, including both Current source columns and Previously unmapped columns.

4.4 Example: restore unmapped columns later

Suppose you first replace 01_base_sheet_source.csv with 02_target_fewer_columns.csv and leave segment and last_order_date unmapped.

Later, you run Change data source again with a source that contains compatible versions of these fields. KAWA shows them in Previously unmapped columns, so you can connect them again.

Click Next after reviewing the mappings.

5. Step 3 — New columns

This step shows columns from the new source that are not used in any existing mapping.

Select the columns you want to add to the sheet.

Extra columns are not added automatically. Only the columns you select in this step are added.

5.1 Example

Replace 01_base_sheet_source.csv with 03_target_auto_match_plus_3.csv.

In this case:

• existing compatible columns are mapped first

• unused columns from the new source appear in New columns

• only the columns you select are added to the sheet

If you do not select any extra columns, they are ignored.

Click Next to continue.

6. Step 4 — Review

Before applying the change, KAWA shows a summary of the result.

The summary includes:

• the current data source

• the new data source

• Columns mapped

• Columns with no data

• New columns

6.1 Example: fewer columns

If you replace 01_base_sheet_source.csv with 02_target_fewer_columns.csv, the review may show:

• Columns mapped: 7 / 9

• Columns with no data: segment, last_order_date

• New columns: None

6.2 Example: additional columns

If you replace 01_base_sheet_source.csv with 03_target_auto_match_plus_3.csv, the review shows:

• the mapped existing columns

• the extra columns you selected in New columns

Review the summary, then click Apply changes.

7. What happens to columns with no data

If a non-key column is left unmapped:

• the column remains in the sheet

• it no longer receives data from the primary source

• its cells remain empty

• its data source is shown as N/A in field information

• it is excluded from parts of the UI that require an active source mapping

7.1 Example

After replacing 01_base_sheet_source.csv with 02_target_fewer_columns.csv:

• segment remains visible in the sheet

• last_order_date remains visible in the sheet

• both columns stay empty until they are remapped in a later replacement

This lets you keep the sheet structure and decide later whether to remap or remove the column.