Retrieve a pre-existing big object via metadata in order to add new fields

Question

Goal

1. Retrieve a pre-existing big object in salesforce.
2. Add new Fields to the metadata
3. and deploy it back to the same org

Question

Can this be done via the workbenches retrieve tool?

Steps Taken so far

I found a previous post with some steps to do this via the ANT migration tool.

So I tried to replicate the steps accept using workbench. I attempted to retrieve the record using the following package.xml file

<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
    <types>
        <members>*</members>
        <name>DCT__b</name>
    </types>
  <version>46.0</version>
</Package>

And got the following:

"problem: Entity type: 'DCT__b' is unknown"

So im definitely doing this wrong. But im struggling to find resources or posts on it. Anyone have advice or resources on how to accomplish my goals above.

Answer 1

The <name> element of the package.xml is the name of the metadata entity you wish to retrieve. The API names of the individual items within that entity which you desire go in the <members> elements.

Here, you need to do something like this:

<types>
    <members>DCT__b</members>
    <name>CustomObject</name>
</types>

The Metadata API functionality is at its core the same regardless of which tool you use (Workbench, Ant, SFDX, CumulusCI, and so on).