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Will this bring a random selection of the data across for each object I select? Can I exclude the record data on an object or would I have to just delete it using dataloader?
I created a Partial copy sandbox just now to verify all details. First you define a Sandbox template, in which you select Objects whose data you want to copy into the sandbox, If data is less than 10000 records it copies whole data.
If data is more than 10000 records i assume it copies any 10000 records.(As in my production there was only limited data).