postgresql - Delete duplicate rows without altering serial number -

i have table duplicate rows except serial number column. want delete rows, have maintain serial number ordering.

what did deleted rows (by using delete command select) , removed serial number column (cid) in tables property section , again add column.

this solved problem there should query update serial numbering.

the query used:

delete ccdoc exists (         select 'x'         ccdoc         i.ref=ccdoc.ref , i.cid < ccdoc.cid);