Support TOP (OFFSET) in GROUP / JSON / PARTITION / FOR operators

[AlexKirkouski]

Example for GROUP (in MyCompany) :

smth = DATA INTEGER (Item);
first = DATA INTEGER (Category);
firstSmth(Category ct) = GROUP SUM smth(Item i) IF level(category(i), ct) ORDER DESC smth(i) TOP first(ct);

EXTEND FORM items
    PROPERTIES (c) first, firstSmth
    PROPERTIES (i) smth
;

Limiting some objects
Example for PARTITION (in MyCompany, using the upper example)

firstSmth(Item i, Category ct) = PARTITION LAST smth(i) IF level(category(i), ct) ORDER DESC smth(i) BY ct TOP first(ct) OFFSET 3;

EXTEND FORM items
    PROPERTIES firstSmth(i, c)
    
    OBJECTS ti = Item
    PROPERTIES name(ti), firstSmth(ti, c), smth(ti)
    FILTERS level(category(ti), c), firstSmth(ti, c)
;

Batching
Example for FOR (in MyCompany)

FOR iterate(INTEGER j, 0, [GROUP SUM 1 IF Item i IS Item]() / 50)  DO 
    NEWSESSION NEWSQL NEWTHREAD {
        sleep(15000);
        APPLY FOR Item i IS Item ORDER i TOP 50 OFFSET j * 50 DO
            smth(i) <- smth(i) + 1;
    }

Paging (for example in API)
Example for JSON (in myCompany)

getItems(STRING nameFilter, INTEGER page, INTEGER pageSize) {
    exportJSON() <- JSON FROM name(Item i) WHERE name(i) LIKE '%'+nameFilter+'%' ORDER name(i) TOP pageSize OFFSET (page - 1) * pageSize;    
}

Query: http://127.0.0.1:7651/exec/getItems?nameFilter=A&page=2&pageSize=50