![]() ![]() The resources allocation to the various slots in terms of CPU, IO and RAM doesn't have to be uniform, as you can give some queues more memory than other, as the queries who are sending to this queue need more memory. If these smaller slots (compare to the default larger 5 slots), are too small for some queries (such as VACUUM or larger reports), you can give these specific queries multiple slots instead of a single one, using wlm_query_slot_count. When you assign the concurrency level of your cluster to 20 for example, you are creating 20 slots of execution. The two concepts of wlm_query_slot_count and memory allocation for a queues are different. I think my question is really about this part of the first quote, "Any unallocated memory is managed by Amazon Redshift and can be temporarily given to a queue if the queue requests additional memory for processing."ĭoes this mean that the user running a query has to specifically request the additional memory? Does this mean that leaving some memory unallocated is of no use unless you make these specific requests? ![]() Is this related to the memory allocation? Can the query slot count adjustment be used to temporarily consume more memory than the whole queue is normally allowed? ![]() The following example sets wlm_query_slot_count to 10, performs a vacuum, and then resets wlm_query_slot_count to 1." "If a specific query needs more memory than is allocated to a single query slot, you can increase the available memory by increasing the wlm_query_slot_count parameter. The remaining 20 percent is unallocated and managed by the service." "Any unallocated memory is managed by Amazon Redshift and can be temporarily given to a queue if the queue requests additional memory for processing.įor example, if you configure four queues, you can allocate memory as follows: 20 percent, 30 percent, 15 percent, 15 percent. However, you also allowed to allocate the memory such that a portion of it remains unallocated. So for example, if you had 5 queues, you might assign each one of them 20% of the memory. When you define Redshift query queues, you can assign the proportion of memory allocated to each queue. ![]()
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