According to v12 docs
Cluster with index scan requires
free space on disk at least equal to the sum of the table size and the index sizes
and cluster with sequential scan and sort requires
as much as double the table size, plus the index sizes
Is there any way out if I do not have that much free space? i.e. can it be run in portions somehow?
If I run CLUSTER command and it fails because of insufficient free disk space will the performed work be entirely rolled back (when run with or without any parameter if it matters)?