Sorry if I am stating what you already know, but... a "pooled sequence" is where the sequence itself encodes the increment So every time we ask it for the next value as part of a SQL insert we get gaps in the generated ids.

So assuming we have a sequence currently sitting at 100 with an increment of 50, and you issue a bulk insert HQL that inserts 10 rows... you just inserted rows with ids of:

1. 150
2. 200
3. 250
4. 300
5. 350
6. 400
7. 450
8. 500
9. 550
10. 600

I am not going to go through the case you mentioned with 6 million rows