Re: Fetch the first record with 24 hr interval based on first record timestamp

Thanks for the DDL and INSERT statements.

I really liked this question and I spend some time tinkering with it.

Unfortunately I did not find an elegant solution for this, since SAP HANA currently doesn't support recursive queries.

Because the new starting point for any 24 hour interval is based on a calculated value in a row "before" the current one and there could be any number of "before" rows, neither join nor sub-select work here.

The solution to this, unfortunately seems to be a procedure:

create global temporary column table my_tmp (record_number bigint, create_date seconddate);
drop procedure max_by_24_hrs;
create procedure max_by_24_hrs (out max_events                                 TABLE (record_number bigint, create_date seconddate))
language SQLSCRIPT as
begin
declare cursor c_raw   for select record_number, create_date                           from test_table                           order by record_number, create_date;
declare curr_grp_record bigint ;
declare curr_grp_date seconddate ;
declare curr_record bigint;
declare curr_date  seconddate;       -- initialize the loop variables    truncate table my_tmp;    select min (record_number), min (create_date)           into curr_grp_record, curr_grp_date    from test_table;  for cr as c_raw  DO            curr_record := cr.record_number;        curr_date := cr.create_date;                -- records group        if :curr_record > :curr_grp_record then        -- new group, new date            curr_grp_record = :curr_record;            curr_grp_date = :curr_date;                        insert into my_tmp values (:curr_record, :curr_grp_date);         elseif (:curr_record = :curr_grp_record             and add_days(:curr_grp_date, 1) <= :curr_date) then          -- same record no, but date is at least a day higher than the last starting point         -- new date            curr_grp_date = :curr_date;               insert into my_tmp values (:curr_record, :curr_grp_date);            end if;                      end for;        max_events =  select * from my_tmp;
end;

call max_by_24_hrs(?);

This version at least avoids dynamic SQL and loops over the data only once.

Would be interesting to see if anyone finds a more elegant or better performing option.

- Lars