az sql db copy - performance characteristics: what is the impact on source db?

I just wanted to enquire, because there is nothing in the documentation, but what are the performance or uptime considerations when executing az sql db copy ?

Like, what is it actually doing behind the scenes?

I ask because for some reason, when managing via az sql db export and az sql db import of bacpacs via storage, it seems to take a very long time, say about 1 to 1.5hrs, even if all in same region, for a large (say 60gb) database. In contrast, az sql db copy seems to do the same without even breaking a sweat, sometimes completing in about 2 to 3 minutes, even between servers?

Why? How does it achieve this speed? And what happens to the source DB during the copy? Is it still available? Is there some kind of cost/pricing dimension involved?

Can bacpacs be processed with similar efficiency?

TL;DR: I want to know if az sql db copy is safe to use with production databases as the source!

Thanks!

[yonzhan]

route to SQL service team to take a look

[tkent]

@yonzhan - would be great to get some confirmation of @t-l-k’s investigation. This is something Microsoft should explain, not something users should have to try to guess at by picking through articles on the internet.