I mean let´s say

the last sequence from two hours ago is 10, the actual sequence is max(sequence), let´s say it´s 13000. During this period we missed 1 sequence, let´s say 10000

so if we use query

select * from your_table
where sequence not between 10 and 13000 you will get 10000 no? Then write 10000 to your file or whatever