Different plan between 9.6 and 9.4 when using "Group by"

Hi team:
The following SQL is very slow in 9.6.1 for the plan has a “sort” node.

SQL text:
explain(analyze, buffers, verbose, timing)WITH m as
(SELECT date,accumulation,prod_type,IF,plan_code, mapping_code, channel, VARIABLE, up_load_data
FROM sdm_actu_fore_up_act_nb
WHERE fk_sdm_actu_fore_up_act_nb = 'd626e902-b3c5-495f-938f-3c6c74fa18da' ) ,
a as
(SELECT date,accumulation,prod_type,IF,plan_code, mapping_code, channel, VARIABLE, up_load_data
FROM m
WHERE date = '1' AND VARIABLE ='FYP_FAC') ,
b as
(SELECT date,mapping_code,channel,up_load_data
FROM SDM_ACTU_FORE_UP_FYP_PROD
WHERE FK_sdm_actu_fore_project_result = 'b9eece0c-60cc-403f-992f-9db9e9b78ee1'
AND date >= '2017-01-31' ) ,
n as
(SELECT a.plan_code,a.mapping_code,a.channel,a.variable,b.date,
CASE WHEN (a.up_load_data::numeric) = 0 THEN 0 ELSE b.up_load_data/(a.up_load_data::numeric) END AS fdyz
FROM a, b
WHERE /*a.plan_code = b.plan_code
and*/ a.mapping_code = b.mapping_code
AND a.channel=b.channel )
SELECT 'b9eece0c-60cc-403f-992f-9db9e9b78ee1' FK_sdm_actu_fore_project_result,
m.plan_code,
m.mapping_code,
m.accumulation,
m.channel,
m.prod_type,
m.if,
m.variable,
'PROF-IF' AS TYPE,

((date_trunc('month',add_months((n.date)::date,(m.date::numeric)))- interval '1 day')::date)::text,
sum((m.up_load_data::numeric)*n.fdyz)
FROM m, n
WHERE m.mapping_code = n.mapping_code AND m.channel = n.channel
GROUP BY m.plan_code,
m.mapping_code,
m.accumulation,
m.channel,
m.prod_type,
m.if,
m.variable,
((date_trunc('month',add_months((n.date)::date,(m.date::numeric)))- interval '1 day')::date)::text
;
===========
Plan in 9.6.2:
QUERY PL
AN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
GroupAggregate (cost=437554.59..437556.52 rows=22 width=352) (actual time=175322.440..192068.748 rows=1072820 loops=1)
Output: 'b9eece0c-60cc-403f-992f-9db9e9b78ee1', m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, 'PROF-IF', ((((date_trunc('month'::text, ((((n.date
)::date + ((((m.date)::numeric)::text || 'months'::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text), sum(((m.up_load_data)::numeric * n.fdyz))
Group Key: m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, ((((date_trunc('month'::text, ((((n.date)::date + ((((m.date)::numeric)::text || 'months
'::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text)
Buffers: shared hit=29835, temp read=168320 written=168320
CTE m
-> Bitmap Heap Scan on public.sdm_actu_fore_up_act_nb (cost=22340.45..386925.95 rows=866760 width=60) (actual time=124.239..368.762 rows=895056 loops=1)
Output: sdm_actu_fore_up_act_nb.date, sdm_actu_fore_up_act_nb.accumulation, sdm_actu_fore_up_act_nb.prod_type, sdm_actu_fore_up_act_nb.if, sdm_actu_fore_up_act_nb.plan_code, sdm_
actu_fore_up_act_nb.mapping_code, sdm_actu_fore_up_act_nb.channel, sdm_actu_fore_up_act_nb.variable, sdm_actu_fore_up_act_nb.up_load_data
Recheck Cond: (sdm_actu_fore_up_act_nb.fk_sdm_actu_fore_up_act_nb = 'd626e902-b3c5-495f-938f-3c6c74fa18da'::text)
Heap Blocks: exact=23005
Buffers: shared hit=29402
-> Bitmap Index Scan on ix_sdm_actu_fore_up_act_nb (cost=0.00..22123.76 rows=866760 width=0) (actual time=119.406..119.406 rows=895056 loops=1)
Index Cond: (sdm_actu_fore_up_act_nb.fk_sdm_actu_fore_up_act_nb = 'd626e902-b3c5-495f-938f-3c6c74fa18da'::text)
Buffers: shared hit=6397
CTE a
-> CTE Scan on m m_1 (cost=0.00..21669.00 rows=22 width=288) (actual time=3.972..743.152 rows=289 loops=1)
Output: m_1.date, m_1.accumulation, m_1.prod_type, m_1.if, m_1.plan_code, m_1.mapping_code, m_1.channel, m_1.variable, m_1.up_load_data
Filter: ((m_1.date = '1'::text) AND (m_1.variable = 'FYP_FAC'::text))
Rows Removed by Filter: 894767
Buffers: shared hit=23004
CTE b
-> Bitmap Heap Scan on public.sdm_actu_fore_up_fyp_prod (cost=124.14..5052.60 rows=2497 width=33) (actual time=2.145..4.566 rows=4752 loops=1)
Output: sdm_actu_fore_up_fyp_prod.date, sdm_actu_fore_up_fyp_prod.mapping_code, sdm_actu_fore_up_fyp_prod.channel, sdm_actu_fore_up_fyp_prod.up_load_data
Recheck Cond: (sdm_actu_fore_up_fyp_prod.fk_sdm_actu_fore_project_result = 'b9eece0c-60cc-403f-992f-9db9e9b78ee1'::text)
Filter: (sdm_actu_fore_up_fyp_prod.date >= '2017-01-31'::text)
Heap Blocks: exact=315
Buffers: shared hit=433
-> Bitmap Index Scan on ix_sdm_actu_fore_up_fyp_prod (cost=0.00..123.52 rows=4746 width=0) (actual time=1.863..1.863 rows=14256 loops=1)
Index Cond: (sdm_actu_fore_up_fyp_prod.fk_sdm_actu_fore_project_result = 'b9eece0c-60cc-403f-992f-9db9e9b78ee1'::text)
Buffers: shared hit=118
CTE n
-> Hash Join (cost=0.77..69.46 rows=1 width=192) (actual time=745.835..756.304 rows=4764 loops=1)
Output: a.plan_code, a.mapping_code, a.channel, a.variable, b.date, CASE WHEN ((a.up_load_data)::numeric = '0'::numeric) THEN '0'::numeric ELSE (b.up_load_data / (a.up_load_data)
::numeric) END
Hash Cond: ((b.mapping_code = a.mapping_code) AND (b.channel = a.channel))
Buffers: shared hit=23437
-> CTE Scan on b (cost=0.00..49.94 rows=2497 width=128) (actual time=2.147..6.445 rows=4752 loops=1)
Output: b.date, b.mapping_code, b.channel, b.up_load_data
Buffers: shared hit=433
-> Hash (cost=0.44..0.44 rows=22 width=160) (actual time=743.661..743.661 rows=289 loops=1)
Output: a.plan_code, a.mapping_code, a.channel, a.variable, a.up_load_data
Buckets: 1024 Batches: 1 Memory Usage: 29kB
Buffers: shared hit=23004
-> CTE Scan on a (cost=0.00..0.44 rows=22 width=160) (actual time=3.974..743.380 rows=289 loops=1)
Output: a.plan_code, a.mapping_code, a.channel, a.variable, a.up_load_data
Buffers: shared hit=23004
-> Sort (cost=23837.58..23837.64 rows=22 width=320) (actual time=175322.411..178986.480 rows=14620032 loops=1)
Output: m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, ((((date_trunc('month'::text, ((((n.date)::date + ((((m.date)::numeric)::text || 'mon
ths'::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text), m.up_load_data, n.fdyz
Sort Key: m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, ((((date_trunc('month'::text, ((((n.date)::date + ((((m.date)::numeric)::text || 'm
onths'::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text)
Sort Method: external merge Disk: 1346544kB
Buffers: shared hit=29835, temp read=168320 written=168320
-> Hash Join (cost=0.04..23837.09 rows=22 width=320) (actual time=884.588..27338.979 rows=14620032 loops=1)
Output: m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, (((date_trunc('month'::text, ((((n.date)::date + ((((m.date)::numeric)::text ||
'months'::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text, m.up_load_data, n.fdyz
Hash Cond: ((m.mapping_code = n.mapping_code) AND (m.channel = n.channel))
Buffers: shared hit=29835
-> CTE Scan on m (cost=0.00..17335.20 rows=866760 width=288) (actual time=124.243..263.402 rows=895056 loops=1)
Output: m.date, m.accumulation, m.prod_type, m.if, m.plan_code, m.mapping_code, m.channel, m.variable, m.up_load_data
Buffers: shared hit=6398
-> Hash (cost=0.02..0.02 rows=1 width=128) (actual time=760.302..760.302 rows=4764 loops=1)
Output: n.date, n.fdyz, n.mapping_code, n.channel
Buckets: 8192 (originally 1024) Batches: 1 (originally 1) Memory Usage: 389kB
Buffers: shared hit=23437
-> CTE Scan on n (cost=0.00..0.02 rows=1 width=128) (actual time=745.838..759.139 rows=4764 loops=1)
Output: n.date, n.fdyz, n.mapping_code, n.channel
Buffers: shared hit=23437
Planning time: 0.383 ms
Execution time: 192187.911 ms
(65 rows)

Time: 192192.814 ms

==========
Plan in 9.4.1
QUERY PL
AN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
HashAggregate (cost=478276.30..478278.89 rows=47 width=352) (actual time=92967.646..93660.910 rows=1072820 loops=1)
Output: 'b9eece0c-60cc-403f-992f-9db9e9b78ee1', m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, 'PROF-IF', ((((date_trunc('month'::text, ((((n.date
)::date + ((((m.date)::numeric)::text || 'months'::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text), sum(((m.up_load_data)::numeric * n.fdyz))
Group Key: m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, (((date_trunc('month'::text, ((((n.date)::date + ((((m.date)::numeric)::text || 'months'
::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text
Buffers: shared hit=30869, temp read=8103 written=8102
CTE m
-> Bitmap Heap Scan on public.sdm_actu_fore_up_act_nb (cost=37491.97..421474.67 rows=942376 width=60) (actual time=158.435..465.865 rows=895056 loops=1)
Output: sdm_actu_fore_up_act_nb.date, sdm_actu_fore_up_act_nb.accumulation, sdm_actu_fore_up_act_nb.prod_type, sdm_actu_fore_up_act_nb.if, sdm_actu_fore_up_act_nb.plan_code, sdm_
actu_fore_up_act_nb.mapping_code, sdm_actu_fore_up_act_nb.channel, sdm_actu_fore_up_act_nb.variable, sdm_actu_fore_up_act_nb.up_load_data
Recheck Cond: (sdm_actu_fore_up_act_nb.fk_sdm_actu_fore_up_act_nb = 'd626e902-b3c5-495f-938f-3c6c74fa18da'::text)
Heap Blocks: exact=23006
Buffers: shared hit=30422
-> Bitmap Index Scan on ix_sdm_actu_fore_up_act_nb (cost=0.00..37256.38 rows=942376 width=0) (actual time=153.180..153.180 rows=895056 loops=1)
Index Cond: (sdm_actu_fore_up_act_nb.fk_sdm_actu_fore_up_act_nb = 'd626e902-b3c5-495f-938f-3c6c74fa18da'::text)
Buffers: shared hit=7416
CTE a
-> CTE Scan on m m_1 (cost=0.00..23559.40 rows=24 width=288) (actual time=5.386..1227.412 rows=289 loops=1)
Output: m_1.date, m_1.accumulation, m_1.prod_type, m_1.if, m_1.plan_code, m_1.mapping_code, m_1.channel, m_1.variable, m_1.up_load_data
Filter: ((m_1.date = '1'::text) AND (m_1.variable = 'FYP_FAC'::text))
Rows Removed by Filter: 894767
Buffers: shared hit=23005, temp written=8101
CTE b
-> Bitmap Heap Scan on public.sdm_actu_fore_up_fyp_prod (cost=221.97..7251.24 rows=2575 width=33) (actual time=2.623..6.318 rows=4752 loops=1)
Output: sdm_actu_fore_up_fyp_prod.date, sdm_actu_fore_up_fyp_prod.mapping_code, sdm_actu_fore_up_fyp_prod.channel, sdm_actu_fore_up_fyp_prod.up_load_data
Recheck Cond: (sdm_actu_fore_up_fyp_prod.fk_sdm_actu_fore_project_result = 'b9eece0c-60cc-403f-992f-9db9e9b78ee1'::text)
Filter: (sdm_actu_fore_up_fyp_prod.date >= '2017-01-31'::text)
Heap Blocks: exact=327
Buffers: shared hit=447
-> Bitmap Index Scan on ix_sdm_actu_fore_up_fyp_prod (cost=0.00..221.32 rows=4920 width=0) (actual time=2.313..2.313 rows=14256 loops=1)
Index Cond: (sdm_actu_fore_up_fyp_prod.fk_sdm_actu_fore_project_result = 'b9eece0c-60cc-403f-992f-9db9e9b78ee1'::text)
Buffers: shared hit=120
CTE n
-> Hash Join (cost=0.84..71.70 rows=2 width=224) (actual time=1230.640..1245.947 rows=4764 loops=1)
Output: a.plan_code, a.mapping_code, a.channel, a.variable, b.date, CASE WHEN ((a.up_load_data)::numeric = 0::numeric) THEN 0::numeric ELSE (b.up_load_data / (a.up_load_data)::nu
meric) END
Hash Cond: ((b.mapping_code = a.mapping_code) AND (b.channel = a.channel))
Buffers: shared hit=23452, temp written=8101
-> CTE Scan on b (cost=0.00..51.50 rows=2575 width=128) (actual time=2.626..8.904 rows=4752 loops=1)
Output: b.date, b.mapping_code, b.channel, b.up_load_data
Buffers: shared hit=447
-> Hash (cost=0.48..0.48 rows=24 width=160) (actual time=1227.982..1227.982 rows=289 loops=1)
Output: a.plan_code, a.mapping_code, a.channel, a.variable, a.up_load_data
Buckets: 1024 Batches: 1 Memory Usage: 21kB
Buffers: shared hit=23005, temp written=8101
-> CTE Scan on a (cost=0.00..0.48 rows=24 width=160) (actual time=5.387..1227.668 rows=289 loops=1)
Output: a.plan_code, a.mapping_code, a.channel, a.variable, a.up_load_data
Buffers: shared hit=23005, temp written=8101
-> Hash Join (cost=0.07..25917.88 rows=47 width=352) (actual time=1410.018..61022.859 rows=14620032 loops=1)
Output: m.plan_code, m.mapping_code, m.accumulation, m.channel, m.prod_type, m.if, m.variable, (((date_trunc('month'::text, ((((n.date)::date + ((((m.date)::numeric)::text || 'mont
hs'::text))::interval))::date)::timestamp with time zone) - '1 day'::interval))::date)::text, m.up_load_data, n.fdyz
Hash Cond: ((m.mapping_code = n.mapping_code) AND (m.channel = n.channel))
Buffers: shared hit=30869, temp read=8103 written=8102
-> CTE Scan on m (cost=0.00..18847.52 rows=942376 width=288) (actual time=158.442..558.052 rows=895056 loops=1)
Output: m.date, m.accumulation, m.prod_type, m.if, m.plan_code, m.mapping_code, m.channel, m.variable, m.up_load_data
Buffers: shared hit=7417, temp read=8103 written=1
-> Hash (cost=0.04..0.04 rows=2 width=128) (actual time=1251.514..1251.514 rows=4764 loops=1)
Output: n.date, n.fdyz, n.mapping_code, n.channel
Buckets: 1024 Batches: 1 Memory Usage: 325kB
Buffers: shared hit=23452, temp written=8101
-> CTE Scan on n (cost=0.00..0.04 rows=2 width=128) (actual time=1230.643..1249.718 rows=4764 loops=1)
Output: n.date, n.fdyz, n.mapping_code, n.channel
Buffers: shared hit=23452, temp written=8101
Planning time: 0.666 ms
Execution time: 93783.172 ms
(60 rows)

Time: 93790.518 ms

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