extsort usage error

[datatraveller1]

I tried to use this command:
qsv extsort --select 1,7 file.csv out.csv

but I get: usage error: extsort CSV mode requires an index
Isn't 1,7 a proper index or am I doing something wrong?
Thank you!

[datatraveller1]

Ah ok, it seems I have to use the index command before:
qsv index file.csv | qsv extsort --select 1,7 file.csv out.csv

[ondohotola]

two separate commands, you don’t (have to) pipe

[datatraveller1]

Thank you, yes two commands are better readable than piping!

qsv index file.csv
qsv extsort --select 1,7 file.csv out.csv