Lagging behind

[nearform]

Lagging behind

[paolochiodi]

Hi.

The idea behind this extension is that history table contains all previous states of a record and the actual table contains the current version of the record.

So:

1. INSERT INTO subscriptions (name, state) VALUES ('test1', 'inserted');
2. subscriptions table contains inserted, subscriptions_history is empty
3. UPDATE subscriptions SET state = 'updated' WHERE name = 'test1';
4. subscriptions contains updated, subscription_history contains inserted
5. DELETE FROM subscriptions WHERE name = 'test1';
6. subscriptions is empty, subscription_history contains inserted and updated

The best way to think about it is that every change to a record in subscriptions will store the previous state of that record in subscriptions_history.

You can see the expected behaviour in the tests: https://github.com/nearform/temporal_tables/blob/master/test/expected/versioning.out#L128

This should be the same behaviour of the original c extension that we ported.