please help me tune the following query:
INSERT INTO rptkys (rptkyskey,runid,tablename,tableky)
(SELECT s_catalog4.nextval, 'R0276518', 'TESTREQ',testreq.testreqkey
FROM testreq,entorder,patient
WHERE (testreq.established
BETWEEN '01/01/2010 00:00'
AND '02/01/2010 00:00' )
AND testreq.requesttype = 'C'
AND entorder.entorderkey = testreq.entorderkey
AND entorder.patientkey = patient.patientkey
AND not testreq.status = 'X'
AND EXISTS (SELECT * from rptkys pssitekeys
WHERE pssitekeys.runid = 'R0276518'
AND pssitekeys.tablename = 'PS_SITE'
AND pssitekeys.tableky = testreq.prea_sitekey)
AND EXISTS (SELECT * from rptkys pwmethkeys
WHERE pwmethkeys.runid = 'R0276518'
AND pwmethkeys.tablename = 'PWMETH'
AND pwmethkeys.tableky = testreq.prea_pwmethkey)
AND 1 = pkg_rptpatsec.ps_granted('R0276518' , 'MGR', NULL,NULL,patient.patseckey)
AND 1 = pkg_rptpatsec.ps_granted('R0276518' , 'MGR', entorder.sfkey,entorder.ptkey)
AND 1 = pkg_rptpatsec.ps_granted('R0276518',testreq.testkey,testreq.issecure))