Database view as cuckoo's egg for an item persistence

Pellet boiler sums up its pellet consumption over time, have this persisted as an item in Postgresql, so the data might be 3775, 3791, 3810 (kg). But I do not have the daily increase, I’d like to have an item with the daily delta for the Analyze view. So, I thought I might try to create an SQL view and put it under an item.

The openHAB persistence creates a table for each persisted item, the table name is item_idx with idx the index in the items table.

INSERT INTO items (itemname) VALUES (‘boilerdailykg’);

This got at index 17, so I created a view

create view boilerdailykg_17 as select time, value - LAG(value) OVER(ORDER BY time) as value from boilertotalkg;

The view uses the LAG positional function.

dbview.items: Number boilerdailykg

boilerdailykg : strategy = restoreOnStartup

restarted openhab, had to switch to month in the Gui Analyze view of the item, and the data line appeared.