![]() On the Query menu, select Include Actual Execution Plan or select the Include Actual Execution Plan toolbar button.Įxecute the query by selecting the Execute toolbar button. You can also open an existing query and display the estimated execution plan by selecting the Open File toolbar button and locating the existing query.Įnter the query for which you would like to display the actual execution plan. On the SQL Server Management Studio toolbar, select Database Engine Query. Include an execution plan for a query during execution For more information, see Monitor your Azure Synapse Analytics dedicated SQL pool workload using DMVs. ![]() FROM sys.dm_exec_cached_plans AS cp CROSS APPLY sys.To retrieve an actual execution plan for dedicated SQL pools (formerly SQL DW) and dedicated SQL pools in Azure Synapse Analytics, there are different commands. Find the plan handle for that query - OPTION (RECOMPILE) keeps this query from going into the plan cache SELECT cp.plan_handle, cp.objtype, cp.usecounts, GO - Run a stored procedure or query EXEC dbo.uspGetEmployeeManagers 9 Example 8 ********************** - Remove one query plan from the cache USE AdventureWorks2014 GO - Clear plan cache for the current database - New in SQL Server 2016 and SQL Azure ALTER DATABASE SCOPED CONFIGURATION CLEAR PROCEDURE_CACHE Flush the plan cache for one database only DBCC FLUSHPROCINDB Example 7 ********************** - Clear plan cache for the current database USE AdventureWorks2014 GO - Example 6 ********************** - Remove all elements from the plan cache for one database (does not work in SQL Azure) - Get DBID from one database name first DECLARE INT Flush the plan cache for one resource pool DBCC FREEPROCCACHE ( 'LimitedIOPool') Example 5 ********************** - Flush the entire plan cache for one resource pool - Get Resource Pool information SELECT name AS, cache_memory_kb/1024.0 AS , Flush the ad hoc and prepared plan cache for one resource pool DBCC FREESYSTEMCACHE ( 'SQL Plans', 'LimitedIOPool') Used_memory_kb/1024.0 AS įROM sys.dm_resource_governor_resource_pools ![]() Example 4 *********************** - Flush the ad hoc and prepared plan cache for one resource pool - Get Resource Pool information SELECT name AS, cache_memory_kb/1024.0 AS , Example 3 *********************** - Flush the ad hoc and prepared plan cache for the entire instance DBCC FREESYSTEMCACHE ( 'SQL Plans') If DBCC printed error messages, contact your system administrator." DBCC FREEPROCCACHE WITH NO_INFOMSGS ![]() Example 2 *********************** - Flush the plan cache for the entire instance and suppress the regular completion message - "DBCC execution completed. Running DBCC FREEPROCCACHE is kind of a brute force approach, so if you are concerned about that, you can run one of the variations shown below: - Eight different ways to clear the plan cache - Glenn Berry - Example 1 *********************** - Remove all elements from the plan cache for the entire instance DBCC FREEPROCCACHE Having said all that, I want to show a few methods for clearing all or part of the plan cache that are somewhat less impactful on the system. That makes it easier to pick out your most expensive queries or stored procedures on a cumulative basis when you are looking at things like total worker time or total logical reads. It can actually be pretty useful for resetting the cached_time time for sys.dm_exec_procedure_stats so that it is the same for most of the stored procedures in your normal workload. It will cause a pretty minor CPU spike for a few seconds on most systems as the query plans get recompiled as they are executed. ![]() I would argue that running DBCC FREEPROCCACHE does not cause that much distress with a modern processor, even on a very busy OLTP system. For each cleared cachestore in the plan cache, the SQL Server error log will contain the following informational message: “SQL Server has encountered %d occurrence(s) of cachestore flush for the ‘%s’ cachestore (part of plan cache) due to ‘DBCC FREEPROCCACHE’ or ‘DBCC FREESYSTEMCACHE’ operations.” This message is logged every five minutes as long as the cache is flushed within that time interval. This can cause a sudden, temporary decrease in query performance. Freeing the plan cache causes, for example, a stored procedure to be recompiled instead of reused from the cache. Use DBCC FREEPROCCACHE to clear the plan cache carefully. Nearly anytime you see the command DBCC FREEPROCCACHE mentioned in a blog post, magazine article or book, you usually get some sort of a scary warning about how you should not use it on a production system, or else life as we know it will end. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |