Appends one or more new row groups to the end of an existing .vtr file
without touching or recompressing existing row groups. The schema of x
must exactly match the schema of the target file (same column names and
types, in the same order).
Details
The operation is not fully atomic: if the process is interrupted after
new row groups are written but before the header is patched, the file
will be in a corrupted state. Use write_vtr() for safety-critical
write-once workloads.