ability to access to transition tables

[gagalago]

transition tables allow to access to all lines changed. it's especialy usefull for statement trigger to be able to apply in the function only what is really needed.

from the postgres documentation (last paragraph):

By default, statement-level triggers do not have any way to examine the individual row(s) modified by the statement. But an AFTER STATEMENT trigger can request that transition tables be created to make the sets of affected rows available to the trigger. AFTER ROW triggers can also request transition tables, so that they can see the total changes in the table as well as the change in the individual row they are currently being fired for. The method for examining the transition tables again depends on the programming language that is being used, but the typical approach is to make the transition tables act like read-only temporary tables that can be accessed by SQL commands issued within the trigger function.

and the syntax of it's definition

do you think it's something that can be integrated into this gem? if yes, how do you see this addition, what need to be changed to be compatible?

[gagalago]

@jenseng what do you think about this? you can also check the associated pull request