Need guidance on re-writing this query - hadoop

Question

Current Scenario => We have a query which we are running on our prod cluster.
this query selects just 3 fields from a join between 1 table and ( nested way of join )another huge table and then performs a groupby at the end but runs for 2 hours on production and it hits one huge table in that join
Query :
INSERT OVERWRITE TABLE mstr_wrk.final_acct_data
SELECT
a0,
a1,
a2,
a3
FROM
(
SELECT
t1.a0 as a0
FROM
(
SELECT
t1.a0 as a0
FROM
(
SELECT
CAST(t1.acct_id AS STRING) as a0
FROM
mstr_wrk.cust_xref t1
)
t1
GROUP BY
t1.a0
)
t1
)
tab1
RIGHT OUTER JOIN
(
SELECT
a0,
a1,
a2
FROM
(
SELECT
(
CASE
WHEN
1 = t1.a1
THEN
t1.a0
ELSE
CAST(NULL AS TIMESTAMP)
END
) as a0, UDFcalldate('TRUNC', UDFcalldate('ADD_TO_DATE',
(
CASE
WHEN
1 = t1.a1
THEN
t1.a0
ELSE
CAST(NULL AS TIMESTAMP)
END
)
, 'D', - 1), 'DD') as a1
FROM
(
SELECT
MAX(t1.a0) as a0,
MAX(t1.a1) as a1
FROM
(
SELECT
load_audit.run_ts as a0,
1 as a1
FROM
mstr_wrk.load_audit
WHERE
val_name = 'card_stg'
)
t1
)
t1
)
tab4
JOIN
(
SELECT
CAST(t1.acct_cd AS STRING) as a0,
CAST(t1.h_acct_cd AS STRING) as a1,
CAST(t1.acct_num AS STRING) as a2,
CAST(t1.load_dt AS TIMESTAMP) as a3,
t1.ts as a4
FROM
mstr_work.acct_crd t1
)
tab3
WHERE
(
tab4.a0 < tab3.a4
)
AND
(
tab4.a1 <= tab3.a3
)
)
tab2
ON (tab1.a0 = tab2.a1)
WHERE
1 =
(
CASE
WHEN
tab1.a0 IS NULL
THEN
1
ELSE
0
END
)
GROUP BY
tab2.a0, tab2.a1, tab2.a2
What I tried -
I tried to enable CBO and vectorization along with ppd but no luck
I dont see any small table here so cant try map side join
One of the joins, which looks like a cross join can be translated to inner join
but is there anyway i can try CTE here
Request -
Kindly guide how can i fix it
is there any better way to rewrite this query.