Postgres 15

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select version();


version


PostgreSQL 15.0 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-10), 64-bit



SELECT 1


CREATE TABLE node (
    id TEXT PRIMARY KEY,
    is_skippable BOOL,
    prev TEXT REFERENCES node(id),
    "next" TEXT REFERENCES node(id)
);

CREATE TABLE


INSERT INTO node VALUES 
  ('A1', FALSE, NULL, 'A2'), 
  ('A2', TRUE, 'A1', 'A3'), 
  ('A3', FALSE, 'A2', NULL),
  ('B1', FALSE, NULL, 'B2'), 
  ('B2', FALSE, 'B1', NULL);

INSERT 0 5


select * from node;


id
is_skippable
prev
next


A1
f
null
A2

A2
t
A1
A3

A3
f
A2
null

B1
f
null
B2

B2
f
B1
null



SELECT 5

id	is_skippable	prev	next
A1	f	null	A2
A2	t	A1	A3
A3	f	A2	null
B1	f	null	B2
B2	f	B1	null