Number of WLM queue
RStoolKit Result: Number of WLM queue
If you are using a manual WLM, then you are limited with 8 custom user defined queues. Also we RedShift allows only 50 concurrent queries. So your 8 queue should share the 50 concurrent slots. (But 1 will be used for Super user queue).
Find the number of queues and their concurrency:
-- Not applicable for Auto WLM select service_class , name, num_query_tasks, query_working_mem FROM stv_wlm_service_class_config WHERE service_class BETWEEN 6 AND 13;
If it is returns a single row, then you are using the default queue. This is also a bad practice.
How to fix this problem:
There is no thumb rule to have the X number of queues. But generally we can optimize our workload within 2 or 3 queues. Because
Less queues with more concurrency + memory = Better individual queries performance.
But some best practices:
- Use upto 3 slots if you know your workload.
- Don’t use more than 15 slots per queue.
- If you don’t know your workload, then switch to Auto WLM.
- WLM system tables and views
- Optimizing WLM