The problem was that the optimize code was not closing both the reader and writer streams before attempting
to rename the file. This will not work on Windows where all file handles have to be closed before the
file can be renamed, moved, or deleted. The fix was to move the close calls before the rename.
We return the error code from my_rename in case of failure but we attempt to reopen the writers and readers
even in the case of failure so that the table can still be usable.
