![]() What permissions are needed for using extended events? Utilizing specific programming techniques, in combination with the predefined reading frequency, allows us to collect even the deadlocks that are significantly delayed as a consequence of the SQL Server system_health extended event limitations explained above and thus maximizing the precision The time period is chosen as it grants the most optimal and precise reading, especially from the system_health extended event. This is a hardcoded setting that cannot be changed by the user. How frequently is the deadlock information collected? (What is the sampling period?)ĪpexSQL Monitor reads data from the selected extended event every 60 seconds. Therefore, when enabled, it allows capturing of all deadlocks with minimal delay, and it is not affected by the server activity level. As being a dedicated extended event explicitly designed for deadlocks monitoring, it doesn’t have any limitations that affect the system_health extended event. When enabled, ApexSQL Monitor will create ApexSQLDeadlock extended event on the monitored SQL Server. This is a customized extended event dedicated to deadlocks collection. However, if it is allowed by the company policy, it is highly recommended to use the dedicated ApexSQLDealock extended event While not being the most reliable due to the previously explained SQL Server limitations it cannot always guarantee the collected deadlock data precision it can still provide enough information in most cases. The max_memory limit is set to 4Mb while the max_event limit is set to 5000 events for the system_health session The reason is that it either reaches the max_memory or max_events limit. Therefore, in the highly active servers it is possible that a large amount of events is 0.5MB in size which limits the available space in the system_health extended event ring_buffer for the deadlock events that are serialized to the XML format (serialized size can be over 4.5MB) so it doesn’t show up in the XEL (event file format) file up until it has been buffered out. To elaborate, the maximum memory assigned to the ring buffer is 4MB. This is not the most reliable method for collecting the deadlocks, and it cannot always be guaranteed that all deadlocks are captured or that deadlocks event might be available with severe delay. The system_health extended event is SQL Server native extended event that, among other information, collects data about the SQL Server deadlocks. The system health extended event – default option What is the difference between the ApexSQLMonitorDeadlock extended event and system_health extended event? ![]() See more information on the ApexSQLDeadlock extended event below To meet the various user preferences, ApexSQL Monitor utilizes two different approaches in the SQL Server deadlocks monitoring: using the SQL Server native system_health extended event or using the ApexSQL Monitor’s dedicated ApexSQLDeadlock extended event. How does ApexSQL Monitor collects SQL Server deadlocks data?ĪpexSQL Monitor SQL Server deadlock monitoring is entirely based on using SQL Server Extended Events. How can I start or stop ApexSQlMonitorDeadlock extended event manually if needed?.Will ApexSQlMonitorDeadlock extended events remain on the monitored instances when I uninstall the application?.What are the Deadlocks metric and does it behaves as any regular SQL Server metric?.Where can I see the details of collected deadlocks?. ![]()
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