Monitors progress by displaying the number of rows processed so far on the terminal (standard error). This number is updated every second or thereabouts; if all the processing is done in under a second you may not see any output. If the total number of rows in the table is known, an ASCII-art progress bar is updated, otherwise just the number of rows seen so far is written.
Note under some circumstances progress may appear to
complete before the actual work of the task is done
since part of the processing involves slurping up the whole
table to provide random access on it.
In this case, applying the
cache upstream may help.