Left joins on multi-million rows

Question

i have a simple query doing left joining on several tables, upward of 7 tables. each table has several hundred million rows.
tblA is 1:M tblB and tblB is 1:M tblC and so on.
how to tune a query liked that?
sample query is
select distinct
a.col,b.col,c.col
from tblA a left join tblB b
on a.id=b.id
and a.col is not null
left join tblC
on b.id=c.id
and c.col > criteria
thanks.

Answer 1

hi
a simple query is liked
SELECT my_DEP.description,
my_DEP.addr_id,
hundredRowsTbl.address,
5MillTbl.checkin_TIME,
5MillTbl.checkout_TIME,
hundredRowsTbl.ID2,
5MillTbl.ID,
5MillTbl.col2,
my_DEP.col3,
5MillTbl.col13,
hundreds.desc,
50mmTbl.col6,
50mmTbl.col5,
5MillTbl.col33
FROM
my.5MillTbl 5MillTbl
LEFT OUTER JOIN
my.50mmTbl 50mmTbl
ON 5MillTbl.ID = 50mmTbl.ID
LEFT OUTER JOIN my.hundreds hundreds
ON 5MillTbl.banding =
hundreds.banding
INNER JOIN my.my_DEP my_DEP
ON 5MillTbl.organization_ID = my_DEP.organization_ID
INNER JOIN my.my_40millTbl
ON 5MillTbl.seqID = my_40millTbl.seqID
LEFT OUTER JOIN my.hundredRowsTbl hundredRowsTbl
ON my_DEP.addr_id = hundredRowsTbl.ID2
LEFT OUTER JOIN my.30millTbl 30millTbl
ON my_DEP.organization_ID = 30millTbl.dept_id
WHERE 1=1
AND 5MillTbl.ID IS NOT NULL
AND ( 5MillTbl.checkout_TIME >= TO_DATE ('01-01-2009 00:00:00', 'DD-MM-YYYY HH24:MI:SS')
AND 5MillTbl.checkout_TIME <TO_DATE ('12-31-2010 00:00:00', 'DD-MM-YYYY HH24:MI:SS')
AND ( 5MillTbl.col2 IS NULL
OR NOT (5MillTbl.col2 = 5
OR 5MillTbl.col2 = 6)
AND 5MillTbl.ID IS NOT NULL
AND 30millTbl.TYPE= '30'
AND my_DEP.addr_id = 61