What
happens if you set the $o ut stage to output to a
collection that already exists?

Question

What
happens if you set the $o ut  stage to output to a
collection that already exists?

Answer

A new database with the specified name of the
collection is created.

Answer

The existing
collection is erased and replaced with the outputted documents.

Answer

An error is returned, and the existing collection is
not modified.

Answer

A second collection with "_1" appended to
the name is created.

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