Note. Some trace flags were introduced in specific SQL Server versions. For more information on the applicable version, see the Microsoft Support article associated. EventSelection.gif' alt='Microsoft Sql Server Slow Query' title='Microsoft Sql Server Slow Query' />Trace Flags Transact SQL Microsoft Docs. THIS TOPIC APPLIES TO SQL Server starting with 2. Azure SQL Database. Azure SQL Data Warehouse Parallel Data Warehouse Trace flags are used to temporarily set specific server characteristics or to switch off a particular behavior. For example, if trace flag 3. SQL Server starts, hardware compression for tape drivers is disabled. Trace flags are frequently used to diagnose performance issues or to debug stored procedures or complex computer systems. The following table lists and describes the trace flags that are available in SQL Server. Note. Some trace flags were introduced in specific SQL Server versions. For more information on the applicable version, see the Microsoft Support article associated with a specific trace flag. I have a relatively large table currently 2 million records and would like to know if its possible to improve performance for adhoc queries. The word adhoc being. This article provides details about updates, improvements, and bug fixes for the current and previous versions of SSMS. Download previous SSMS versions below. Query. I had the same problem as the original poster but the quoted answer did not solve the problem for me. The query still ran really slow from a stored procedure. Identify and troubleshoot the reasons behind slow running queries In SQL Server and know how they can be the cause of a bad performance of SQL Server. We are excited to announce that SQL Server 2017 images on Linux and Windows are now available in the Azure Marketplace Deploying SQL Server in Azure VMs. Important. Trace flag behavior may not be supported in future releases of SQL Server. Trace flag. Description. Forces correct conversion semantics in the scope of DBCC check commands like DBCC CHECKDB, DBCC CHECKTABLE and DBCC CHECKCONSTRAINTS, when analyzing the improved precision and conversion logic introduced with compatibility level 1. For more information, see this Microsoft Support article. Note This trace flag applies to SQL Server 2. RTM CU3, SQL Server 2. SP1 and higher builds. SQL Server Performance monitoring and troubleshooting is a critical part of SQL Server Database Administration. This video shows how to perform simple 12. Updated 20161103 Updated with TF 10210 We have written a lot about Microsoft SQL Server Trace Flags in our blog, so. The 1 SQL Server community and education site, with articles, news, forums, scripts and FAQs. WARNING Trace flag 1. Microsoft Support article. It should be immediately disabled after validation checks are completed. Scope global only. Increases the SQL Server Database Engine plan cache bucket count from 4. For more information, see this Microsoft Support article. Note Please ensure that you thoroughly test this option, before rolling it into a production environment. Scope global only. Enables a fix to address errors when rebuilding partitions online for tables that contain a computed partitioning column. For more information, see this Microsoft Support article. Scope global or session. Reports to the error log when a statistics dependent stored procedure is being recompiled as a result of auto update statistics. For more information, see this Microsoft Support article. Scope global only. Prints versioning information about extended stored procedure dynamic link libraries DLLs. For more information about Get. Xp. Version, see Creating Extended Stored Procedures. Scope global or session. Disables identity pre allocation to avoid gaps in the values of an identity column in cases where the server restarts unexpectedly or fails over to a secondary server. Note that identity caching is used to improve INSERT performance on tables with identity columns. Note Starting with SQL Server 2. IDENTITYCACHE option in ALTER DATABASE SCOPED CONFIGURATION Transact SQL. Scope global only. Controls minimally logged inserts into indexed tables. This trace flag is not required starting SQL Server 2. In SQL Server 2. 01. Rows inserted into existing pages no new page allocation to maintain index order are still fully logged, as are rows that are moved as a result of page splits during the load. It is also important to have ALLOWPAGELOCKS turned ON for indexes which is ON by default for minimal logging operation to work as page locks are acquired during allocation and thereby only page or extent allocations are logged. For more information, see Data Loading Performance Guide. Scope global or session. Forum Hack Black Ops Ps3 Ign. Disables the background columnstore compression task. SQL Server periodically runs the Tuple Mover background task that compresses columnstore index rowgroups with uncompressed data, one such rowgroup at a time. Columnstore compression improves query performance but also consumes system resources. You can control the timing of columnstore compression manually, by disabling the background compression task with trace flag 6. ALTER INDEX. REORGANIZE or ALTER INDEX. REBUILD at the time of your choice. Scope global only. Disables page pre fetching scans. For more information, see this Microsoft Support article. Scope global or session. Disables the ghost record removal process. For more information, see this Microsoft Support article. Scope global only. Disables fast inserts while bulk loading data into heap or clustered index. Starting SQL Server 2. With fast inserts, each bulk load batch acquires new extents bypassing the allocation lookup for existing extent with available free space to optimize insert performance. With fast inserts, bulk loads with small batch sizes can lead to increased unused space consumed by objects hence it is recommended to use large batchsize for each batch to fill the extent completely. If increasing batchsize is not feasible, this traceflag can help reduce unused space reserved at the expense of performance. Note This trace flag applies to SQL Server 2. RTM and higher builds. Scope global or session. Enables table lock for bulk load operations into a heap with no non clustered indexes. When this trace flag is enabled, bulk load operations acquire bulk update BU locks when bulk copying data into a table. Bulk update BU locks allow multiple threads to bulk load data concurrently into the same table, while preventing other processes that are not bulk loading data from accessing the table. The behavior is similar to when the user explicitly specifies TABLOCK hint while performing bulk load, or when the sptableoption table lock on bulk load is enabled for a given table. However, when this trace flag is enabled, this behavior becomes default without any query or database changes. Scope global or session. Uses Microsoft Windows large page allocations for the buffer pool. For more information, see this Microsoft Support article. Note If you are using the Columnstore Index feature of SQL Server 2. SQL Server 2. 01. Scope global only. Bypasses execution of database upgrade script when installing a Cumulative Update or Service Pack. If you encounter an error during script upgrade mode, it is recommended to contact Microsoft SQL Customer Service and Support CSS for further guidance. For more information, see this Microsoft Support article. WARNING This trace flag is meant for troubleshooting of failed updates during script upgrade mode, and it is not supported to run it continuously in a production environment. Database upgrade scripts needs to execute successfully for a complete install of Cumulative Updates and Service Packs. Not doing so can cause unexpected issues with your SQL Server instance. Scope global only. When a file in the filegroup meets the autogrow threshold, all files in the filegroup grow. Note Starting with SQL Server 2. AUTOGROWSINGLEFILE and AUTOGROWALLFILES option of ALTER DATABASE, and trace flag 1. For more information, see ALTER DATABASE File and Filegroup Options Transact SQL. Scope global only. Removes most single page allocations on the server, reducing contention on the SGAM page. When a new object is created, by default, the first eight pages are allocated from different extents mixed extents. Afterwards, when more pages are needed, those are allocated from that same extent uniform extent. The SGAM page is used to track these mixed extents, so can quickly become a bottleneck when numerous mixed page allocations are occurring. This trace flag allocates all eight pages from the same extent when creating new objects, minimizing the need to scan the SGAM page. For more information, see this Microsoft Support article. Note Starting with SQL Server 2. SET MIXEDPAGEALLOCATION option of ALTER DATABASE, and trace flag 1. For more information, see ALTER DATABASE SET Options Transact SQL. Scope global only. Returns the resources and types of locks participating in a deadlock and also the current command affected. For more information, see this Microsoft Support article. Scope global only. Disables lock escalation based on memory pressure, or based on number of locks. The SQL Server Database Engine will not escalate row or page locks to table locks. Using this trace flag can generate excessive numbers of locks. This can slow the performance of the Database Engine, or cause 1. If both trace flag 1. Updated Microsoft SQL Server Trace Flag list. Updated 2. 01. 6 1. Updated with TF 1. We have written a lot about Microsoft SQL Server Trace Flags in our blog, so I thought it was about time to start making a list, of known and unknown Trace Flags. The goal is of course to create the best SQL Server Trace Flag list in the world. And the most complete SQL Server Trace Flag list in the world. First some info to get you started What are Microsoft SQL Server Trace FlagsTrace Flags are settings that in some way or another alters the behaviour of various SQL Server functions. How do I turn Trace Flags on and off You can use the DBCC TRACEON and DBCC TRACEOFF commands You can use the T option in the startup configuration fo the SQL Server Service You can also use the hint QUERYTRACEON in your queries lt querytraceonhint QUERYTRACEON traceflagnumber How do I know what Trace Flags are turned on at the moment You can use the DBCC TRACESTATUS command. REMEMBER Be extremely careful with trace flags, test in your test environment first. And consult professionals first if you are the slightest uncertain about the effects of your changes. General Links SQL Server Central TF List http www. MSDN TF list http sqlserverpedia. TraceFlags. Albert van der Sel TF list http antapex. Technet Wiki TF list http social. Amit Banerjee TF list http troubleshootingsql. Paul Randal discussing TF Pros and Cons http www. Some trace flags needs to be specified with t rather than with T in startup options Thanks to Lars Utterstrm. Martin Hglund. Hkan Winther. Toine Rozemeijer. Robert L Davis aka sqlsoldiersqlhandle aka sqlhandle. Andrzej Kukua. Wilfred van Dijk. So, here is the list, but it is just the beginning. We will continue to add more flags, and more information as we go along. Trace Flag 1. 01. Function Verbose Merge Replication logging output for troubleshooting Merger repl performance. Link http support. Trace Flag 1. 02. Function Verbose Merge Replication logging to msmergehistory table for troubleshooting Merger repl performance. Link http support. Trace Flag 1. 05. Function Join more than 1. SQL server 6. 5. Link http www. SQL Server 6. 5 Some Useful Trace Flags. Trace Flag 1. 06. Function This enables you to see the messages that are sent to and from the Publisher, if you are using Web Synchronization. Link http technet. Trace Flag 1. 07. Function Alter input rules for decimal numbers. Link http support. Thanks to http www. Trace Flag 1. 68. Function Bugfix in ORDER BYLink http support. Trace Flag 2. 05. Function Log usage of Auto. StatAuto Update Statistics. Link http support. Trace Flag 2. 53. Function Prevent adhoc query plans from staying in cache SQL 2. Link http www. ForumsTopic. Trace Flag 2. 60. Function Prints Extended stord proc DLL versioning info. Link http msdn. Trace Flag 2. Function Grenerates a log record per identity increment. Can be users to convert SQL 2. Indetity behaviour. Link http www. Link https connect. SQLServerfeedbackdetails7. Trace Flag 3. 02. Function Output Index Selection info. Link http www. SQL Server 6. Some Useful Trace Flags. Trace Flag 3. 10. Function Outputs info about actual join order. Link http www. SQL Server 6. Some Useful Trace Flags. Trace Flag 3. 23. Function Outputs detailed info about updates. Link http www. SQL Server 6. Some Useful Trace Flags. Trace Flag 3. 45. Function Changes join order selection logic in SQL Server 6. Link http www. SQL Server 6. Some Useful Trace Flags. Trace Flag 4. 45. Function Prints compile issued message in the errorlog for each compiled statement, when used together with 3. Link NATrace Flag 6. Function Minimally logged inserts to indexed tables. Link http msdn. SQL. Trace Flag 6. 17. Function Revert to old style lock wait list behaviour in SQL 2. Link https blogs. Thanks to Hkan Winther. Trace Flag 6. 52. Function Disable page pre fetching scans. Link http support. Trace Flag 6. 61. Function  Disable the ghost record removal process. Link http support. Trace Flag 6. 62. Function Prints detailed information about the work done by the ghost cleanup task when it runs next. Use TF 3. 60. 5 to see the output in the errorlog. Link http blogs. Trace Flag 8. Function  Turn on Page Audit functionality, to verify page validity. Link http technet. Trace Flag 8. 18. Function  Turn on ringbuffer to store info about IO write operations. Used to troubleshoot IO problems. Link http support. Trace Flag 8. 30. Function Disable diagnostics for stalled and stuck IO operations. Link https support. Trace Flag 8. 34. Function Large Page Allocations. Link http sqlservice. Link http support. Trace Flag 8. 36 Function Use the max server memory option for the buffer pool. Link http support. Trace Flag 8. 45. Function Enable Lock pages in Memory on Standard Edition. Link http sqlservice. Trace Flag 9. 02. Function Bypass Upgrade Scripts. Link http sqlservice. Trace Flag 1. 11. Function Simultaneous Autogrowth in Multiple file database. Link http sqlservice. Link http blogs. Trace Flag 1. Function Force Uniform Extent Allocation. Link http sqlservice. Link http blogs. Trace Flag 1. Function Turns of mixed extent allocation Similar to 1. Link http social. Trace Flag 1. 14. Function Fix for growing tempdb in special cases. Link http support. Trace Flag 1. 20. Function Prints detailed lock information. Link http social. Trace Flag 1. 12. Function Unknown. Has been reportedly found turned on in some SQL Server instances running Dynamics AX. Also rumored to be invalid in public builds of SQL Server. Link NATrace Flag 1. Function Returns info about deadlocks. Link http msdn. Trace Flag 1. Function Disables Lock escalation caused by mem pressure. Link http msdn. Trace Flag 1. Function Returns Deadlock info in XML format. Link http msdn. Trace Flag 1. Function Disables lock escalation based on number of locks. Link http msdn. Trace Flag 1. Function Fixes performance problem in scenarios with high lock activity in SQL 2. SQL 2. 01. 4Link  http support. Trace Flag 1. 26. Function Collect process names in non yielding scenario memory dumps. Link http support. Trace Flag 1. 44. Function Alters replication logreader functionality. Link http msdn. Trace Flag 1. Function Allow Failover. Partner connections to the former Mirror with Database Mirroring being off. Link https blogs. Preconditions. Link https blogs. Thanks to Wilfred van Dijk. Trace Flag 1. 46. Function Disable Mirroring Log compression. Link http sqlcat. Trace Flag 1. 71. Function MSShipped bit will be set automatically at Create time when creating stored procedures. Link None. Trace Flag 1. Function Performance fix for misaligned IOs. Link http quadtree ab. SLOW RESTORES when migrating SQL Server from old to new hardware1. Link https support. Trace Flag 1. 80. Function Disable Instant File Initialization. Link https msdn. Link  http technet. Trace Flag 1. 80. Function Enable option to have database files on SMB share for SQL Server 2. R2. Link  http blogs. Trace Flag 2. 30. Function Enable advanced decision support optimizations. Link http support. Trace Flag 2. 31. Function Forces the query optimizer to use the SQL Server 2. SQL Server 2. 01. Link http support. Trace Flag 2. 33. Function Generates Query Plans optimized for less memory. Link http support. Trace Flag 2. 34. Function Disable specific SORT optimization in Query Plan. Link http support. Trace Flag 2. 37. Function Change threshold for auto update stats. Link http www. Trace Flag 2. Function Displays memory utilization during the optimization process.