Fill factor for later bigserial + index I'm planning to import and update a huge table (3 Bil. rows) in the following step:


create table with fill factor x
import the data from csv files (6 files, ~21GB each)
add a BIGSERIAL column
create index for the BIGSERIAL column
cluster the table by the BIGSERIAL column?
update one column in the table in batches specified by a range of the BIGSERIAL column


It's a huge operation for me, so I really need your advice on the fill factor x I need to set in step 1, so that it'll have the best impact on the subsequent steps. All columns in the table definition are fixed size. Step 6 is supposed to be most CPU-intensive, since it involves spatial queries (postGIS).
Assuming you are using COPY to populate the table I don't see a reason to create the table without the bigserial column. 

Just create the table including the bigserial, but don't specify it in the COPY command. It will then automatically be filled with values during the import.

create table foobar (id bigserial, col1 text, col2 text);
copy foobar (col1, col2) 
   from 'foobar.txt'
   with (format csv, header false, delimiter ',');


That would remove steps 3,4 and 5.

I'm not sure what you mean with "range of bigserial" in step 6.