There is a step to track when the new heap is written, but this was
missing in the documentation.
Author: Noriyoshi Shinoda
Discussion: https://postgr.es/m/AT5PR8401MB06447FAE88E1592754E958B8EE640@AT5PR8401MB0644.NAMPRD84.PROD.OUTLOOK.COM
Backpatch-through: 12
<command>CLUSTER</command> is currently sorting tuples.
</entry>
</row>
+ <row>
+ <entry><literal>writing new heap</literal></entry>
+ <entry>
+ <command>CLUSTER</command> is currently writing the new heap.
+ </entry>
+ </row>
<row>
<entry><literal>swapping relation files</literal></entry>
<entry>