On the frontend would one store page=1,page=2 or page=user_id(10000th),page=user_id(20000th)
?
1000 is tiny by DB standards but solutions like this one are often bolted without considerations.
I note this use case can be solved using keyset pagination instead of offset/limit, because the ordering of messages is stable: messages are never inserted in the middle of the list; they are appended at the end. We can attribute a number to each message, and use this message to filter and sort.
To do that aforedescribed accounting for us, and more.
If we have an pagination index over (topicId, deleted) on postTime asc.
/threads?id=${USER_NAME}&next=${NEXT_COMMENT_ID}