Postgres 13

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create table the_table (datetime 	timestamp, number int, content text);

CREATE TABLE


insert into the_table
values
  ('2018-01-01 02:49:04', 1, 'spring'),
  ('2018-01-01 02:49:10', 1, 'spring'),
  ('2018-01-01 02:49:24', 1, 'spring'),
  ('2018-01-01 02:49:29', 1, 'summer'),
  ('2018-01-01 02:49:44', 1, 'spring'),
  ('2018-01-01 02:49:49', 1, 'spring'),
  ('2018-01-01 02:49:50', 1, 'winter'),
  ('2018-01-01 02:49:51', 1, 'spring');

INSERT 0 8


with flagged as (
  select ctid as rid, 
         row_number() over w as rn,
         datetime - lag(datetime) over w < interval '10 seconds' as small_gap
  from the_table
  window w as (partition by number, content order by datetime)
)
delete from the_table
where ctid in (select rid
               from flagged
               where small_gap
                 and rn > 1);

DELETE 3


select *
from the_table
order by datetime;


datetime
number
content


2018-01-01 02:49:04
1
spring

2018-01-01 02:49:24
1
spring

2018-01-01 02:49:29
1
summer

2018-01-01 02:49:44
1
spring

2018-01-01 02:49:50
1
winter



SELECT 5

datetime	number	content
2018-01-01 02:49:04	1	spring
2018-01-01 02:49:24	1	spring
2018-01-01 02:49:29	1	summer
2018-01-01 02:49:44	1	spring
2018-01-01 02:49:50	1	winter