WIP: System Versioned Temporal Table

Hi all ,

Temporal table is one of the main new features added in sql standard 2011.
From that I will like to implement system versioned temporal table which
allows to keep past and present data so old data can be queried. Am propose
to implement it like below

CREATE

In create table only one table is create and both historical and current
data will be store in it. In order to make history and current data
co-exist row end time column will be added implicitly to primary key.
Regarding performance one can partition the table by row end time column
order to make history data didn't slowed performance.

INSERT

In insert row start time column and row end time column behave like a kind
of generated stored column except they store current transaction time and
highest value supported by the data type which is +infinity respectively.

DELETE and UPDATE

The old data is inserted with row end time column seated to current
transaction time

SELECT

If the query didn’t contain a filter condition that include system time
column, a filter condition will be added in early optimization that filter
history data.

Attached is WIP patch that implemented just the above and done on top of
commit b8e19b932a99a7eb5a. Temporal clause didn’t implemented yet so one
can use regular filter condition for the time being

NOTE: I implement sql standard syntax except it is PERIOD FOR SYSTEM TIME
rather than PERIOD FOR SYSTEM_TIME in CREATE TABLE statement and system
time is not selected unless explicitly asked

Any enlightenment?

regards

Surafel