help required in Tuning this query

 Hi,

The below query runs for more than 30 hrs,the query tries to fetch rows through db link 

can some one help me in tuning this query,

Version :10.2.0.4

O/s: linux

Waitevent: Db file sequential read

Optimizer_mode :first _rows

select

dept,

eqtype,

COUNT (qlims_test),

qlims_test,

analyte,

mfmethod,

mrttmethod,

qmethodname,

servgrp,

frequency_type,

schedule,

needdbde

from

(

select distinct

s.id_text,

a.testcode as "NewLIMS TestCode",

q.qlims_test,

q.analyte as "Analyte Number",

a.analyte,

a.dilute,

mrtt.eqtype,

t.teststatus,

a.status as "Analyte Status",

mf.frequency_type,

mf.schedule,

mf.dept,

mf.load_type as "Individual or Batch",