SELECT  ss0.USER_ID, ss0.session_id, ss0.SESSION_START, ss0.next_session,
RANK() over(PARTITION BY ss0.USER_ID, ss0.session_id ORDER BY ss0.USER_ID, ss0.session_id, vp.TIMESTAMP2) SESSION_ACTION_ID,
vp.*
from(
    SELECT p2.id, p2.USER_ID, p2.page, p2.TIMESTAMP2 SESSION_START,
    ROW_NUMBER() over(ORDER BY p2.user_id,p2.TIMESTAMP2) session_id,
    LAG(p2.TIMESTAMP2, 1, p2.TIMESTAMP2+100000000) over(PARTITION BY p2.USER_ID ORDER BY p2.user_id,p2.TIMESTAMP2 desc) next_session
    FROM (
        SELECT p1.ID, p1.USER_ID, p1.PAGE, p1.TIMESTAMP2,
        LAG(p1.TIMESTAMP2, 1, p1.TIMESTAMP2-3601) OVER (PARTITION BY p1.USER_ID ORDER BY p1.TIMESTAMP2) - p1.TIMESTAMP2 session_lag
        FROM PUBLIC.VIMBOX_PAGES p1
        WHERE USER_ID in (15,12)
        ORDER BY USER_ID,TIMESTAMP2
    ) p2
    WHERE -1*(p2.session_lag)>3600
)ss0 -- session_starters
LEFT JOIN PUBLIC.VIMBOX_PAGES vp ON vp.USER_ID = ss0.USER_ID AND vp.TIMESTAMP2>=ss0.SESSION_START AND vp.TIMESTAMP2<ss0.next_session