BigQuery slowdown

[jonscarbrough]

Our default BQ commitment quota was 0. I could run an on-demand query processing 26T of data in about 7-10 mins. I made a request to add increase our BQ commitment so that I could create FLEX reservations and see if I could improve the time of the queries. I've tried with 10K slot reservations but the queries now won't finish in an hour. As I analyzed the queries before this quota increase, it appears the max slot usage was 2K. It would seem obvious that using more slots (10K vs 2K) would yield a faster query processing time but it has had the opposite effect. Anyone else experienced this?

[samar]

Hello,

I agree that using more slots (10K vs 2K) would yield a faster query processing time if you run the same query on the same data.

Unfortunately we cannot see the root cause of the behavior you are reporting unless we have the Job ID of the query you are comparing with/without  slots reservation Or at least you can share the execution detail of each query.

Sincerely