Keyset pagination with composite key - sql

Question

I am using oracle 12c database and I have a table with the following structure:
Id NUMBER
SeqNo NUMBER
Val NUMBER
Valid VARCHAR2
A composite primary key is created with the field Id and SeqNo.
I would like to fetch the data with Valid = 'Y' and apply ketset pagination with a page size of 3. Assume I have the following data:
Id SeqNo Val Valid
1 1 10 Y
1 2 20 N
1 3 30 Y
1 4 40 Y
1 5 50 Y
2 1 100 Y
2 2 200 Y
Expected result:
----------------------------
Page 1
----------------------------
Id SeqNo Val Valid
1 1 10 Y
1 3 30 Y
1 4 40 Y
----------------------------
Page 2
----------------------------
Id SeqNo Val Valid
1 5 50 Y
2 1 100 Y
2 2 200 Y
Offset pagination can be done like this:
SELECT * FROM table ORDER BY Id, SeqNo OFFSET 3 ROWS FETCH NEXT 3 ROWS ONLY;
However, in the actual db it has more than 5 millions of records and using OFFSET is going to slow down the query a lot. Therefore, I am looking for a ketset pagination approach (skip records using some unique fields instead of OFFSET)
Since a composite primary key is used, I need to offset the page with information from more than 1 field.
This is a sample SQL that should work in PostgreSQL (fetch 2nd page):
SELECT * FROM table WHERE (Id, SeqNo) > (1, 4) AND Valid = 'Y' ORDER BY Id, SeqNo LIMIT 3;
How do I achieve the same in oracle?

Answer 1

Use row_number() analytic function with ceil arithmetic fuction. Arithmetic functions don't have a negative impact on performance, and row_number() over (order by ...) expression automatically orders the data without considering the insertion order, and without adding an extra order by clause for the main query. So, consider :
select Id,SeqNo,
ceil(row_number() over (order by Id,SeqNo)/3) as page
from tab
where Valid = 'Y';
P.S. It also works for Oracle 11g, while OFFSET 3 ROWS FETCH NEXT 3 ROWS ONLY works only for Oracle 12c.
Demo

Answer 2

You can use order by and then fetch rows using fetch and offset like following:
Select ID, SEQ, VAL, VALID FROM TABLE
WHERE VALID = 'Y'
ORDER BY ID, SEQ
--FETCH FIRST 3 ROWS ONLY -- first page
--OFFSET 3 ROWS FETCH NEXT 3 ROWS ONLY -- second pages
--OFFSET 6 ROWS FETCH NEXT 3 ROWS ONLY -- third page
--Update--
You can use row_number analytical function as following.
Select id, seqNo, Val, valid from
(Select t.*,
Row_number(order by id, seq) as rn from table t
Where valid = 'Y')
Where ceil(rn/3) = 2 -- for page no. 2
Cheers!!