![]() ![]() reallocate resources from a data load queue to an analytics queue once all data has been loaded. Also bear in mind that "concurrency" and "percent of memory" are dynamic WLM configuration properties and you can change them using the CLI ( Modif圜lusterParameterGroup) without having to restart the cluster, e.g. While increasing concurrency allows more queries to run, each query will get a smaller share of the memory allocated to its queue (unless you increase it). ![]() The recommended concurrent level for reporting/querying queue is 5-7. You can also use WLM Query Queue Hopping to manage queries that end up waiting for slots to become free by diverting them to a different queue. The total number of concurrent level should be less than 15. Those queues will typically be used by BI and analytics tools to query the data. Many cluster WLM configurations will have more than one queue, maybe one or two with few slots and therefore a higher resource-to-slot ratio that can be used for a smaller number of resource hungry tasks like data loads and updates, and some with more slots with a lower amount of resources per slot. Query monitoring rules define metrics-based performance boundaries for WLM queues and specify what action to take when a query goes beyond those boundaries. This is not quite true if short query acceleration (SQA) is enabled on the cluster, as in that case very short queries (typically 5 seconds or less) will be run in a special hidden queue if there are no normal slots available. by specifying wlm_query_slot_count as 2 the query will use two slots instead of one, and therefore up to 40% of memory.īe careful doing this though as if you up the slot count to 5 (in this example) then no other queries will be able to run as there are now no available slots. However, you can override the default behaviour, e.g. The rest of the slots will sit idle waiting for another query to hit the same queue. Yep, that's pretty much how Redshift WLM works.įor example if it's configured with one queue and that queue has five slots each with 20% of memory then your one query is by default going to run in one slot and use up to 20% memory max. Amazon Redshift workload management (WLM) enables users to flexibly manage priorities within workloads so that short, fast-running queries won't get stuck in queues behind long-running queries. ![]()
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