same query but different result on pg16devel and pg15.2

From: tender wang <tndrwang(at)gmail(dot)com>
To: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: same query but different result on pg16devel and pg15.2
Date: 2023-04-04 02:53:32
Message-ID: CAHewXNmwhOqWuPWUvNgpGXr5VcoT+d=ckL784tPaiYaomrasnQ@mail.gmail.com
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Hi hackers,
I encounter a problem, as shown below:

query:
select
ref_0.ps_suppkey as c0,
ref_1.c_acctbal as c1,
ref_2.o_totalprice as c2,
ref_2.o_orderpriority as c3,
ref_2.o_clerk as c4
from
public.partsupp as ref_0
left join public.nation as sample_0
inner join public.customer as sample_1
on (false)
on (true)
left join public.customer as ref_1
right join public.orders as ref_2
on (false)
left join public.supplier as ref_3
on (false)
on (sample_0.n_comment = ref_1.c_name )
where (8 <= NULLIF(CASE WHEN (o_orderkey IS NOT NULL) THEN 4 ELSE 4 END,
CASE WHEN (o_orderdate >= o_orderdate) THEN 95 ELSE 95 END))
order by c0, c1, c2, c3, c4 limit 1;

on pg16devel:
c0 | c1 | c2 | c3 | c4
----+----+----+----+----
1 | | | |
(1 row)
plan:
QUERY PLAN

---------------------------------------------------------------------------------------
Limit
-> Sort
Sort Key: ref_0.ps_suppkey, c_acctbal, o_totalprice,
o_orderpriority, o_clerk
-> Nested Loop Left Join
-> Seq Scan on partsupp ref_0
-> Result
One-Time Filter: false
(7 rows)

on pg15.2:
c0 | c1 | c2 | c3 | c4
----+----+----+----+----
(0 rows)
plan:
QUERY
PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
-> Sort
Sort Key: ref_0.ps_suppkey, c_acctbal, o_totalprice,
o_orderpriority, o_clerk
-> Hash Left Join
Hash Cond: ((n_comment)::text = (c_name)::text)
Filter: (8 <= NULLIF(CASE WHEN (o_orderkey IS NOT NULL) THEN
4 ELSE 4 END, CASE WHEN (o_orderdate >= o_orderdate) THEN 95 ELSE 95 END))
-> Nested Loop Left Join
-> Seq Scan on partsupp ref_0
-> Result
One-Time Filter: false
-> Hash
-> Result
One-Time Filter: false
(13 rows)

regards, tender
wang

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