REPLACE under system_versioning_insert_history allows to change existing historical records

create or replace table t (a int primary key) with system versioning;

insert into t values (1);

select a, row_start, row_end from t;

set system_versioning_insert_history= on;

replace into t (a,row_start,row_end) select a, '2023-01-01', row_end from t;

select a, row_start, row_end from t;

a	row_start	row_end

1	2022-10-09 00:58:24.584052	2038-01-19 05:14:07.999999

set system_versioning_insert_history= on;

replace into t (a,row_start,row_end) select a, '2023-01-01', row_end from t;

select a, row_start, row_end from t;

a	row_start	row_end

1	2023-01-01 00:00:00.000000	2038-01-19 05:14:07.999999

create table t (a int primary key, s timestamp(6) as row start, e timestamp(6) as row end, period for system_time(s,e)) with system versioning;

insert into t (a) values (1);

delete from t;

select * from t for system_time all;

set statement system_versioning_alter_history=keep for alter table t add unique (a,s);

set system_versioning_insert_history= on;

replace into t (a,s,e) select a, s, '2023-01-01' from t for system_time all;

select * from t for system_time all;

select * from t for system_time all;

a	s	e

1	2022-10-09 01:08:08.430845	2022-10-09 01:08:08.433748

set statement system_versioning_alter_history=keep for alter table t add unique (a,s);

set system_versioning_insert_history= on;

replace into t (a,s,e) select a, s, '2023-01-01' from t for system_time all;

select * from t for system_time all;

a	s	e

1	2022-10-09 01:08:08.430845	2023-01-01 00:00:00.000000