How to modify fields in data warehouse transfers

Follow these steps to add, remove, or modify fields in your data warehouse transfers.

Instructions

Step 1: Find out which table group to modify

If you're not sure which table group is used in the transfer you want to modify, follow these steps:

1. Go to Transfers on the Supermetrics Hub. 
2. Find the transfer you want to modify.
3. Click the three-dots button, and click Edit.
4. Scroll down to Schema and check the name of the table group (also known as schema).

Step 2: Modify the fields in the table group

If you know which table group to modify, follow these steps:

1. Open the Table Manager on the Supermetrics Hub.
2. Select the data source in use from the right-side panel.
3. Expand the table group that you'd like to modify.
4. Click the table that you'd like to modify.
5. Modify the fields based on your need from the left-side panel.
6. If you want, you can click Preview Data to preview the data.
7. Click Save changes, and select Save changes.

About table group migration

Table group migration is a process that updates the structure of tables in a data warehouse (destination tables) to align with the structure set in the table group. This process happens when you make changes to a table group.

This process ensures that the structure of a table in the data warehouse matches the structure set in the table group and handles the migration without losing relevant historical data. 

Here's an overview of the process:

1. Detect Changes: The process begins by identifying differences between the current destination table and the structure of each table in the group. The migration process is kicked off if changes are detected.
2. Check for locks: Before any changes are made, the system checks if the destination table is being used by another process.
3. Migration execution: If a table is free and changes are detected, the migration process starts.
   • A new temporary table is created with the updated table structure. This includes adding new columns that appear in the new table structure and removing columns that are no longer needed.
   • Data from the existing table that fits within the new table structure is transferred to the new version of the destination table, ensuring that no relevant historical data is lost.
   • Once the data is successfully transferred, the old version of the table is removed, and the new version takes its place.
4. Completion: When the migration is done, every table in the group matches the setup outlined in the table group, and all the important historical data is kept for any columns that are still there.

Note that historical data will be lost for columns that don't exist in the new table structure.