drop table tttest;

create table tttest (

price_id int4,

price_val int4,

price_on abstime,

price_off abstime

);

create unique index tttest_idx on tttest (price_id,price_off);

alter table tttest add column q1 text;

alter table tttest add column q2 int;

alter table tttest drop column q1;

create trigger timetravel

before insert or delete or update on tttest

for each row

execute procedure

timetravel (price_on, price_off);

insert into tttest values (1, 1, null, null);

insert into tttest(price_id, price_val) values (2, 2);

insert into tttest(price_id, price_val,price_off) values (3, 3, 'infinity');

insert into tttest(price_id, price_val,price_off) values (4, 4,

abstime('now'::timestamp - '100 days'::interval));

insert into tttest(price_id, price_val,price_on) values (3, 3, 'infinity'); -- duplicate key

select * from tttest;

delete from tttest where price_id = 2;

select * from tttest;

-- what do we see ?

-- get current prices

select * from tttest where price_off = 'infinity';

-- change price for price_id == 3

update tttest set price_val = 30 where price_id = 3;

select * from tttest;

-- now we want to change price_id from 3 to 5 in ALL tuples

-- but this gets us not what we need

update tttest set price_id = 5 where price_id = 3;

select * from tttest;

-- restore data as before last update:

select set_timetravel('tttest', 0); -- turn TT OFF!

select get_timetravel('tttest'); -- check status

delete from tttest where price_id = 5;

update tttest set price_off = 'infinity' where price_val = 30;

select * from tttest;

-- and try change price_id now!

update tttest set price_id = 5 where price_id = 3;

select * from tttest;

-- isn't it what we need ?

select set_timetravel('tttest', 1); -- turn TT ON!

select get_timetravel('tttest'); -- check status

-- we want to correct some date

update tttest set price_on = 'Jan-01-1990 00:00:01' where price_id = 5 and

price_off <> 'infinity';

-- but this doesn't work

-- try in this way

select set_timetravel('tttest', 0); -- turn TT OFF!

select get_timetravel('tttest'); -- check status

update tttest set price_on = '01-Jan-1990 00:00:01' where price_id = 5 and

price_off <> 'infinity';

select * from tttest;

-- isn't it what we need ?

-- get price for price_id == 5 as it was '10-Jan-1990'

select * from tttest where price_id = 5 and

price_on <= '10-Jan-1990' and price_off > '10-Jan-1990';