Trace Flag: -1
Function: Sets trace flags for all client connections, rather than for a single client connection. Because trace flags set using the -T command-line option automatically apply to all connections, this trace flag is used only when setting trace flags using DBCC TRACEON and DBCC TRACEOFF.
Link: http://www.sql-server-performance.com/2002/traceflags/
Trace Flag: 101
Function: Verbose Merge Replication logging output for troubleshooting Merger repl performance
Link: http://support.microsoft.com/kb/2892633
Trace Flag: 102
Function: Verbose Merge Replication logging to msmerge_history table for troubleshooting Merger repl performance
Link: http://support.microsoft.com/kb/2892633
Trace Flag: 105
Function: Join more than 16 tables in SQL server 6.5
Link: http://www.databasejournal.com/features/mssql/article.php/1443351/SQL-Server-65-Some-Useful-Trace-Flags.htm
Trace Flag: 106
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.microsoft.com/en-us/library/ms151872(v=sql.105).aspx
Trace Flag: 107
Function: SQL 6.5/7/8 Interprets numbers with a decimal point as float instead of decimal
Link: http://support.microsoft.com/kb/203787
Link: https://support.microsoft.com/en-us/kb/155714
Trace Flag: 110
Function: SQL 6.5 Turns off ANSI select characteristics
Link: https://support.microsoft.com/en-us/kb/152032
Trace Flag: 144
Function: Force server side bucketization. For legacy applications where change to client side code is not an option and when the application has queries that are improperly parameterized, this trace flag forces server side bucketization.
Link: http://blogs.msdn.microsoft.com/sqlprogrammability/2007/01/13/6-0-best-programming-practices
Trace Flag: 146
Function: Consider using when replaying against SQL 8.0, to avoid an attempt to set an encrypted connection.
Link: None
Trace Flag: 168
Function: Bugfix in ORDER BY
Link: http://support.microsoft.com/kb/926292
Trace Flag: 174
Function: Increases the SQL Server Database Engine plan cache bucket count from 40,009 to 160,001 on 64-bit systems.
Note: Please ensure that you thoroughly test this option, before rolling it into a production environment.
Link: https://support.microsoft.com/en-us/kb/3026083
Link: MSDN ms188396
Scope: global only
Trace Flag: 204
Function: SQL 6.5 Backward compatibility switch that enables non-ansi standard behavior. E.g. previously SQL server ignored trailing blanks in the like statement and allowed queries that contained aggregated functions to have items in the group by clause that were not in the select list.
Link: None
Trace Flag: 205
Function: Reports to the error log when a statistics-dependent stored procedure is being recompiled as a result of auto-update statistics.
Link: https://support.microsoft.com/en-us/kb/195565
Link: MSDN ms188396
Scope: global only
Trace Flag: 206
Function: SQL 6.5 Provides backward compatibility for the set user statement. KB 160732
Link: None
Trace Flag: 208
Function: SET QUOTED IDENTIFIER ON
Link: None
Trace Flag: 210
Function: SQL 9 Error when you run a query against a view: "An error occurred while executing batch"
Link: https://support.microsoft.com/en-us/kb/945892
Trace Flag: 212
Function: SQL 9 Query may run much slower when compared to SQL 8 when you use a cursor to run the query
Link: https://support.microsoft.com/en-us/kb/951184
Trace Flag: 237
Function: Tells SQL Server to use correlated sub-queries in Non-ANSI standard backward compatibility mode
Link: None
Trace Flag: 242
Function: Provides backward compatibility for correlated subqueries where non-ANSI-standard results are desired
Link: None
Trace Flag: 243
Function: Provides backward compatibility for nullability behavior. When set, SQL Server has the same nullability violation behavior as that of a ver 4.2: Processing of the entire batch is terminated if the nullability error (inserting NULL into a NOT NULL field) can be detected at compile time; Processing of offending row is skipped, but the command continues if the nullability violation is detected at run time.Behavior of SQL Server is now more consistent because nullability checks are made at run time and a nullability violation results in the command terminating and the batch or transaction process continuing.
Link: None
Trace Flag: 244
Function: Disables checking for allowed interim constraint violations. By default, SQL Server checks for and allows interim constraint violations. An interim constraint violation is caused by a change that removes the violation such that the constraint is met, all within a single statement and transaction. SQL Server checks for interim constraint violations for self-referencing DELETE statements, INSERT, and multi-row UPDATE statements. This checking requires more work tables. With this trace flag you can disallow interim constraint violations, thus requiring fewer work tables.
Link: None
Trace Flag: 246
Function: Derived or NULL columns must be explicitly named in a select…INTO or create view statement when not done they raise an error. This flag avoids that.
Link: None
Trace Flag: 253
Function: Prevents ad-hoc query plans to stay in cache
Link: http://www.sqlservercentral.com/Forums/Topic837613-146-1.aspx
Trace Flag: 257
Function: Will invoke a print algorithm on the XML output before returning it to make the XML result more readable
Link: None
Trace Flag: 260
Function: Prints versioning information about extended stored procedure dynamic-link libraries (DLLs). For more information about GetXpVersion(), see Creating Extended Stored Procedures .
Link: http://msdn.microsoft.com/en-us/library/ms164627.aspx
Link: MSDN ms188396
Scope: global or session
Trace Flag: 262
Function: SQL 7 Trailing spaces are no longer truncated from literal strings in CASE statements
Link: https://support.microsoft.com/en-us/kb/891116
Trace Flag: 272
Function: Generates a log record per identity increment. Can be users to convert SQL 2012 back to old style Identity behaviour
Link: http://www.big.info/2013/01/how-to-solve-sql-server-2012-identity.html
Link: https://connect.microsoft.com/SQLServer/feedback/details/739013/failover-or-restart-results-in-reseed-of-identity
Trace Flag: 302
Function: Output Index Selection info
Link: http://www.databasejournal.com/features/mssql/article.php/1443351/SQL-Server-65-Some-Useful-Trace-Flags.htm
Trace Flag: 310
Function: Outputs info about actual join order
Link: http://www.databasejournal.com/features/mssql/article.php/1443351/SQL-Server-65-Some-Useful-Trace-Flags.htm
Trace Flag: 320
Function: Disables join-order heuristics used in ANSI joins. To see join-order heuristics use flag 310. SQL Server uses join-order heuristics to reduce of permutations when using the best join order.
Link: None
Trace Flag: 323
Function: Outputs detailed info about updates
Link: http://www.databasejournal.com/features/mssql/article.php/1443351/SQL-Server-65-Some-Useful-Trace-Flags.htm
Trace Flag: 325
Function: Prints information about the cost of using a non-clustered index or a sort to process an ORDER BY clause
Link: None
Trace Flag: 326
Function: Prints information about estimated & actual costs of sorts. Instructs server to use arithmetic averaging when calculating density instead of a geometric weighted average when updating statistics. Useful for building better stats when an index has skew on the leading column. Use only for updating the stats of a table/index with known skewed data.
Link: None
Trace Flag: 330
Function: Enables full output when using the SET SHOWPLAN_ALL option, which gives detailed information about joins
Link: None
Trace Flag: 342
Function: Disables the costing of pseudo-merge joins, thus significantly reducing time spent on the parse for certain types of large, multi-table joins. One can also use SET FORCEPLAN ON to disable the costing of pseudo-merge joins because the query is forced to use the order specified in the FROM clause.
Link: None
Trace Flag: 345
Function: Changes join order selection logic in SQL Server 6.5
Link: http://www.databasejournal.com/features/mssql/article.php/1443351/SQL-Server-65-Some-Useful-Trace-Flags.htm
Trace Flag: 445
Function: Prints ”compile issued” message in the errorlog for each compiled statement, when used together with 3605
Link: None
Trace Flag: 506
Function: Enforces SQL-92 standards regarding null values for comparisons between variables and parameters. Any comparison of variables and parameters that contain a NULL always results in a NULL.
Link: None
Trace Flag: 610
Function: Controls minimally logged inserts into indexed tables.
Link: http://msdn.microsoft.com/en-us/library/dd425070%28v=SQL.100%29.aspx
Link: https://www.pythian.com/blog/minimally-logged-operations-data-loads/
Link: https://msdn.microsoft.com/library/dd425070.aspx
Link: MSDN ms188396
Scope: global or session
Trace Flag: 611
Function: SQL 9 When turned on, each lock escalation is recorded in the error log along with the SQL Server handle number. Aaron confirmed this still works in SQL 2014. Outputs info of the form: "Escalated locks - Reason: LOCK_THRESHOLD, Mode: S, Granularity: TABLE, Table: 222623836, HoBt: 150:256, HoBt Lock Count: 6248, Escalated Lock Count: 6249, Line Number: 1, Start Offset: 0, SQL Statement: select count(*) from dbo.BigTable"
Link: None
Trace Flag: 617
Function: SQL 9 When turned on, each lock escalation is recorded in the error log along with the SQL Server handle number. As long as there are no SCH_M lock requests waiting in the ‘lock wait list’, the ‘lock wait list’ will be bypassed by statements issued in uncommitted read transaction isolation level. If there is a SCH_M lock request in the ‘lock wait list’, a query in uncommitted read transaction isolation level will not bypass the ‘lock wait list’, but the SCH_S lock request will go into the ‘lock wait list’. In order behind the SCH_M lock waiting in the same list. As a result the grant of the SCH_S request for such a query is dependent on the grant and release of the SCH_M lock request entering the ‘lock wait list’ earlier.
Link: https://blogs.msdn.microsoft.com/saponsqlserver/2014/01/17/new-functionality-in-sql-server-2014-part-3-low-priority-wait/
Trace Flag: 634
Function: 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 634, and then explicitly invoking ALTER INDEX REORGANIZE or ALTER INDEX REBUILD at the time of your choice.
Link: Niko Neugebauer Columnstore Indexes part 35
Link: MSDN ms188396
Scope: global only
Trace Flag: 646
Function: Serves for getting detailed information on which Columnstore were eliminated by the Query Optimiser right into the error log.
Link: Niko Neugebauer Columnstore Indexes part 35
Trace Flag: 647
Function: Avoids a new-in-SQL 2012 data check (done when adding a column to a table) that can cause ALTER TABLE... ADD operations to take a very long time. The KB has a useful query for determining the row size for a table.
Link: https://support.microsoft.com/en-us/help/2986423/fix-it-takes-a-long-time-to-add-new-columns-to-a-table-when-the-row-size-exceeds-the-maximum-allowed-size
Trace Flag: 652
Function: Disable page pre-fetching scans
Link: KB920093 ]
Link: MSDN ms188396
Scope: global only
Trace Flag: 653
Function: Disables read ahead for the current connection
Link: None
Trace Flag: 661
Function: Disables the ghost record removal process.
Link: KB920093
Link: MSDN ms188396
Scope: global only
Trace Flag: 662
Function: Prints detailed information about the work done by the ghost cleanup task when it runs next. Use TF 3605 to see the output in the errorlog
Link: http://blogs.msdn.com/b/sqljourney/archive/2012/07/28/an-in-depth-look-at-ghost-records-in-sql-server.aspx
Trace Flag: 669
Function: “...prevents user queries from queuing requests to the ghost cleanup process”. This flag is a workaround for stack dumps occurring right after SQL Server startup, where user queries (that queue pages for ghost cleanup) were running so quickly after SQL startup that they were queuing pages before the ghost cleanup process had actually initialized.
Link: https://support.microsoft.com/en-us/help/3027860/error-17066-or-17310-during-sql-server-startup
Trace Flag: 698
Function: SQL 9 Performance of INSERT operations against a table with an identity column may be slow when compared to SQL 8
Link: https://support.microsoft.com/en-gb/kb/940545
Trace Flag: 699
Function: Turn off transaction logging for the entire SQL dataserver
Link: None
Trace Flag: 670, 671
Function: Disables deferred deallocation. But note Paul White’s comment on the post! The flag # may actuall by 671.
Link: https://blogs.msdn.microsoft.com/psssql/2009/11/17/how-it-works-controlling-sql-server-memory-dumps/
Trace Flag: 715
Function: 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 sp_tableoption 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.
Link: MSDN ms188396
Scope: global or session
Trace Flag: 806
Function: Turn on Page Audit functionality, to verify page validity
Link: http://technet.microsoft.com/en-au/library/cc917726.aspx
Trace Flag: 809
Function: SQL 8 Limits the amount of Lazy write activity
Link: None
Trace Flag: 815
Function: SQL 8/9 Enables latch enforcement. SQL Server 8 (with service pack 4) and SQL Server 9 can perform latch enforcement for data pages found in the buffer pool cache. Latch enforcement changes the virtual memory protection state while database page status changes from "clean" to "dirty" ("dirty" means modified through INSERT, UPDATE or DELETE operation). If an attempt is made to modify a data page while latch enforcement is set, it causes an exception and creates a mini-dump in SQL Server installation's LOG directory. Microsoft support can examine the contents of such mini-dump to determine the cause of the exception. In order to modify the data page the connection must first acquire a modification latch. Once the data modification latch is acquired the page protection is changed to read-write. Once the modification latch is released the page protection changes back to read-only.
Link: None
Trace Flag: 818
Function: Turn on ringbuffer to store info about IO write operations. Used to troubleshoot IO problems
Link: http://support.microsoft.com/kb/826433
Trace Flag: 828
Function: SQL 8 - When enabled checkpoint ignores the recovery interval target and keeps steady I/O otherwise it uses recovery interval setting as a target for the length of time that checkpoint will take
Link: https://support.microsoft.com/en-gb/kb/906121 Link: https://blogs.msdn.microsoft.com/psssql/2008/04/11/how-it-works-sql-server-checkpoint-flushcache-outstanding-io-target/
Trace Flag: 830
Function: SQL 9 Disable the reporting of CPU Drift errors in the SQL Server errorlog like SQL Server has encountered 2 occurrence(s) of I/O requests taking longer than 15 seconds to complete
Link: https://support.microsoft.com/en-us/kb/897284 Link: https://technet.microsoft.com/en-us/library/aa175396(v=SQL.80).aspx
Trace Flag: 831
Function: Protect unchanged pages in the buffer pool to catch memory corruptions
Link: None
Trace Flag: 834
Function: Uses Microsoft windows large-page allocations for the buffer pool.
Note: If you are using the Columnstore Index feature of SQL Server 2012 to SQL Server 2016, we do not recommend turning on trace flag 834.
Link: https://support.microsoft.com/en-us/kb/920093
Link: https://support.microsoft.com/en-us/kb/3210239
Link: MSDN ms188396
Scope: global only
Trace Flag: 835
Function: SQL 9 / 10 On 64 bit SQL Server it turns off Lock pages in memory
Link: None
Trace Flag: 836
Function: Use the max server memory option for the buffer pool
Link: KB920093 Link: https://blogs.msdn.microsoft.com/psssql/2012/12/11/how-it-works-sql-server-32-bit-paeawe-on-sql-2005-2008-and-2008-r2-not-using-as-much-ram-as-expected/
Trace Flag: 839
Function: (Apparently) forces SQL Server to treate all NUMA memory as “flat”, as if it was SMP.
Link: https://blogs.msdn.microsoft.com/psssql/2010/04/02/how-it-works-soft-numa-io-completion-thread-lazy-writer-workers-and-memory-nodes
Trace Flag: 840
Function: SQL 9 When trace turned on, SQL Server can perform larger I/O extent reads to populate the buffer pool when SQL Server starts this populates the buffer pool faster. Additionally, the larger I/O extent reads improve the initial query compilation and the response time when SQL Server starts.
Link: https://blogs.msdn.microsoft.com/ialonso/2011/12/09/the-read-ahead-that-doesnt-count-as-read-ahead
Trace Flag: 842
Function: Use sys.dm_os_memory_node_access_stats to verify local vs. foreign memory under NUMA configurations after turning on this flag
Link: None
Trace Flag: 845
Function: Enable Lock pages in Memory on Standard Edition
Link: https://support.microsoft.com/en-gb/kb/970070 Link: https://support.microsoft.com/en-us/help/2708594/fix-locked-page-allocations-are-enabled-without-any-warning-after-you-upgrade-to-sql-server-2012
Trace Flag: 851
Function: According to Bob Ward’s PASS 2014 talk on SQL Server IO, “disable[s] BPE even if enabled via ALTER SERVER”Link: None
Trace Flag: 902
Function: 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.
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.
Link: https://support.microsoft.com/en-us/kb/2163980
Link: MSDN ms188396
Scope: global only
Trace Flag: 1106
Function: SQL 9 - Used space in tempdb increases continuously when you run a query that creates internal objects in tempdb
Link: https://support.microsoft.com/en-gb/kb/947204
Link: https://blogs.msdn.microsoft.com/arvindsh/2014/02/24/tracking-tempdb-internal-object-space-usage-in-sql-2012
Trace Flag: 1117
Function: When a file in the filegroup meets the autogrow threshold, all files in the filegroup grow.
Note: Beginning with SQL Server 2016 this behavior is controlled by the AUTOGROW_SINGLE_FILE and AUTOGROW_ALL_FILES option of ALTER DATABASE, and trace flag 1117 has no affect. For more information, see ALTER DATABASE File and Filegroup Options (Transact-SQL).
Link: https://www.littlekendra.com/2017/01/03/parallelism-and-tempdb-data-file-usage-in-sql-server/
Link: SQL Server 2016 : Getting tempdb a little more right
Link: MSDN ms188396
Link: http://www.sqlskills.com/blogs/paul/tempdb-configuration-survey-results-and-advice Link: https://blogs.msdn.microsoft.com/ialonso/2011/12/01/attempt-to-grow-all-files-in-one-filegroup-and-not-just-the-one-next-in-the-autogrowth-chain-using-trace-flag-1117 Link: http://sql-articles.com/articles/general/day-6trace-flag-1117-auto-grow-equally-in-all-data-file Scope: global only
Trace Flag: 1118
Function: 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.
Note: Beginning with SQL Server 2016 this behavior is controlled by the SET MIXED_PAGE_ALLOCATION option of ALTER DATABASE, and trace flag 1118 has no affect. For more information, see ALTER DATABASE SET Options (Transact-SQL).
Link: http://blogs.msdn.com/b/psssql/archive/2008/12/17/sql-server-2005-and-2008-trace-flag-1118-t1118-usage.aspx
Link: http://www.sqlskills.com/blogs/paul/misconceptions-around-tf-1118/
Link: https://support.microsoft.com/en-us/kb/328551
Link: SQL Server 2016 : Getting tempdb a little more right
Link: MSDN ms188396
Link: https://chrisadkin.org/2015/04/14/well-known-and-not-so-well-known-sql-server-tuning-knobs-and-switches
Scope: global only
Trace Flag: 1119
Function: Turns of mixed extent allocation (Similar to 1118?)
Link: TECHNET List Of SQL Server Trace Flags
Trace Flag: 1124
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: None
Trace Flag: 1140
Function: A workaround for a bug in SQL 2005 SP2, SP3, and SQL 2008, where mixed page allocations climb continually, due to a change in the way that mixed-page allocations are done.
Link: None
Trace Flag: 1165
Function: This presentation by Bob Ward says that this TF outputs the recalculated #’s (every 8192 allocations) for the proportional fill algorithm in database allocation when multiple files are present..
Link: None
Trace Flag: 1180
Function: SQL 7 - Forces allocation to use free pages for text or image data and maintain efficiency of storage. Helpful in case when DBCC SHRINKFILE and SHRINKDATABASE commands may not work because of sparsely populated text, ntext, or image columns.
Link: None
Trace Flag: 1197
Function: Applies only in the case of SQL 7 SP3, similar with trace flag 1180
Link: None
Trace Flag: 1200
Function: Prints detailed lock information as every request for a lock is made (the process ID and type of lock requested)
Link: TECHNET List Of SQL Server Trace Flags Link: https://blogs.msdn.microsoft.com/sqlserverstorageengine/2008/03/30/tempdb-table-variable-vs-local-temporary-table
Link: https://support.microsoft.com/en-us/help/169960/inf-analyzing-and-avoiding-deadlocks-in-sql-server
Trace Flag: 1202
Function: Insert blocked lock requests into syslocks
Link: None
Trace Flag: 1204
Function: Returns the resources and types of locks participating in a deadlock and also the current command affected.
Link: https://support.microsoft.com/en-us/kb/832524
Link: MSDN ms188396
Scope: global only
Trace Flag: 1205
Function: More detailed information about the command being executed at the time of a deadlock. Documented in SQL 7 BOL.
Link: https://support.microsoft.com/en-us/help/832524/sql-server-technical-bulletin---how-to-resolve-a-deadlock
Trace Flag: 1206
Function: Used to complement flag 1204 by displaying other locks held by deadlock parties
Link: https://support.microsoft.com/en-us/help/169960/inf-analyzing-and-avoiding-deadlocks-in-sql-server
Trace Flag: 1208
Function: KB: “Prints the host name and program name supplied by the client. This can help identify a client involved in a deadlock, assuming the client specifies a unique value for each connection.”
Link: https://support.microsoft.com/en-us/help/169960/inf-analyzing-and-avoiding-deadlocks-in-sql-server
Trace Flag: 1211
Function: 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 1204 errors (unable to allocate lock resource) because of insufficient memory. If both trace flag 1211 and 1224 are set, 1211 takes precedence over 1224. However, because trace flag 1211 prevents escalation in every case, even under memory pressure, we recommend that you use 1224. This helps avoid "out-of-locks" errors when many locks are being used.
Link: MSDN ms188396
Link: http://www.sqlskills.com/blogs/paul/a-sql-server-dba-myth-a-day-2330-lock-escalation
Scope: global or session
Trace Flag: 1216
Function: SQL 7 - Disables Health reporting. Lock monitor when detects a (worker thread) resource level blocking scenario. If a SPID that owns a lock is currently queued to the scheduler, because all the assigned worker threads have been created and all the assigned worker threads are in an un-resolvable wait state, the following error message is written to the SQL Server error log: Error 1223: Process ID %d:%d cannot acquire lock "%s" on resource %s because a potential deadlock exists on Scheduler %d for the resource. Process ID %d:% d holds a lock "%h" on this resource.
Link: None
Trace Flag: 1222
Function: Returns the resources and types of locks that are participating in a deadlock and also the current command affected, in an XML format that does not comply with any XSD schema.
Link: MSDN ms188396
Scope: global only
Trace Flag: 1224
Function: Disables lock escalation based on the number of locks. However, memory pressure can still activate lock escalation. The Database Engine escalates row or page locks to table (or partition) locks if the amount of memory used by lock objects exceeds one of the following conditions:
Forty percent of the memory that is used by Database Engine. This is applicable only when the locks parameter of sp_configure is set to 0. Forty percent of the lock memory that is configured by using the locks parameter of sp_configure.For more information, see Server Configuration Options (SQL Server) . If both trace flag 1211 and 1224 are set, 1211 takes precedence over 1224. However, because trace flag 1211 prevents escalation in every case, even under memory pressure, we recommend that you use 1224. This helps avoid "out-of-locks" errors when many locks are being used.
Note: Lock escalation to the table- or HoBT-level granularity can also be controlled by using the LOCK_ESCALATION option of the ALTER TABLE statement.
Link: MSDN ms188396
Scope: global or session
Trace Flag: 1228
Function: Enable lock partitioning. By default, lock partitioning is enabled when a server has 16 or more CPUs. Otherwise, lock partitioning is disabled. Trace flag 1228 enables lock partitioning for 2 or more CPUs. Trace flag 1229 disables lock partitioning. Trace flag 1229 overrides trace flag 1228 if trace flag 1228 is also set. Lock partitioning is useful on multiple-CPU servers where some tables have very high lock rates. You can turn on trace flag 1228 and trace flag 1229 only at startup.
Link: Trace Flag 1228 and 1229
Link: Microsoft SQL Server 2005 TPC-C Trace Flags
Trace Flag: 1229
Function: Enable lock partitioning. By default, lock partitioning is enabled when a server has 16 or more CPUs. Otherwise, lock partitioning is disabled. Trace flag 1228 enables lock partitioning for 2 or more CPUs. Trace flag 1229 disables lock partitioning. Trace flag 1229 overrides trace flag 1228 if trace flag 1228 is also set. Lock partitioning is useful on multiple-CPU servers where some tables have very high lock rates. You can turn on trace flag 1228 and trace flag 1229 only at startup.
Link: Trace Flag 1228 and 1229
Link: Microsoft SQL Server 2005 TPC-C Trace Flags
Trace Flag: 1236
Function: Enables database lock partitioning. Fixes performance problem in scenarios with high lock activity in SQL 2012 and SQL 2014.
Note: Beginning with SQL Server 2012 SP3 and SQL Server 2014 SP1 this behavior is controlled by the engine and trace flag 1236 has no effect.
Link: https://support.microsoft.com/en-us/kb/2926217
Link: MSDN ms188396
Scope: global only
Trace Flag: 1260
Function: Disabled mini-dump for non-yield condition. Disables mini-dump generation for "any of the 17883, 17884, 17887, or 17888 errors. The trace flag can be used in conjunction with trace flag T1262. For example, you could enable T1262 to get 10- and a 60-second interval reporting and also enable T1260 to avoid getting mini-dumps."
Link: A Topical Collection of SQL Server Flags v6
Link: How To Diagnose and Correct Errors 17883, 17884, 17887, and 17888
Link: MSDN ms188396
Scope: global only
Trace Flag: 1261
Function: SQL 8 - Disables Health reporting. Lock monitor when detects a (worker thread) resource level blocking scenario. If a SPID that owns a lock is currently queued to the scheduler, because all the assigned worker threads have been created and all the assigned worker threads are in an un-resolvable wait state, the following error message is written to the SQL Server error log: Error 1229: Process ID %d:%d owns resources that are blocking processes on scheduler %d.
Link: None
Trace Flag: 1262
Function: The default behavior (for 1788* errors) is for SQL to generate a mini-dump on the first occurrence, but never after. 1262 changes the behavior: “When T1262 is enabled, a mini-dump is generated when the non-yielding condition is declared (15 seconds) and at subsequent 60-second intervals for the same non-yield occurrence. A new nonDiagCorrect17883etc; yielding occurrence causes dump captures to occur again.” In SQL 2000 this was a startup-only flag; in 2005+ it can be enabled via TRACEON. Note that the flag is also covered in Khen2005, p400, but with no new information.
Link: A Topical Collection of SQL Server Flags v6
Link: How To Diagnose and Correct Errors 17883, 17884, 17887, and 17888
Trace Flag: 1264
Function: Collect process names in non-yielding scenario memory dumps
Link: A Topical Collection of SQL Server Flags v6
Link: http://support.microsoft.com/kb/2630458/en-us
Trace Flag: 1400
Function: SQL 9 RTM Enables creation of database mirroring endpoint, which is required for setting up and using database mirroring
Link: None
Trace Flag: 1439
Function: Trace database restart and failover messages to SQL Errorlog for mirrored databases
Link: Trace flags in sql server from trace flag 902 to trace flag 1462
Trace Flag: 1448
Function: Enables the replication log reader to move forward even if the async secondaries have not acknowledged the reception of a change. Even with this trace flag enabled the log reader always waits for the sync secondaries. The log reader will not go beyond the min ack of the sync secondaries. This trace flag applies to the instance of SQL Server, not just an availability group, an availability database, or a log reader instance. Takes effect immediately without a restart. This trace flag can be activated ahead of time or when an async secondary fails.
Link: https://support.microsoft.com/en-us/kb/937041
Link: MSDN ms188396
Scope: global only
Trace Flag: 1449
Function: When you use SNAC to connect to an instance of a principal server in a database mirroring session: "The connection attempted to fail over to a server that does not have a failover partner".
Link: https://support.microsoft.com/en-gb/kb/936179
Trace Flag: 1462
Function: Disables log stream compression for asynchronous availability groups. This feature is enabled by default on asynchronous availability groups in order to optimize network bandwidth.
Link: http://sqlcat.com/sqlcat/b/technicalnotes/archive/2007/09/17/database-mirroring-log-compression-in-sql-server-2008-improves-throughput.aspx
Link: MSDN mt736907
Link: MSDN ms188396
Scope: global only
Trace Flag: 1482
Function: Prints information to the Error Log (3605 is not necessary) for a variety of transaction log operations are done, including when the MinLSN value is reset, when a VLF is formatted, etc.
Link: None
Trace Flag: 1504
Function: Dynamic memory grant expansion can also help with parallel index build plans where the distribution of rows across threads is uneven. The amount of memory that can be consumed this way is not unlimited, however. SQL Server checks each time an expansion is needed to see if the request is reasonable given the resources available at that time. Some insight to this process can be obtained by enabling undocumented trace flag 1504, together with 3604 (for message output to the console) or 3605 (output to the SQL Server error log). If the index build plan is parallel, only 3605 is effective because parallel workers cannot send trace messages cross-thread to the console.
Link: Internals of the Seven SQL Server Sorts Part 1
Trace Flag: 1603
Function: Use standard disk I/O (i.e. turn off asynchronous I/O)
Link: None
Trace Flag: 1604
Function: Once enabled at start up makes SQL Server output information regarding memory allocation requests
Link: None
Trace Flag: 1609
Function: Turns on the unpacking and checking of RPC information in Open Data Services. Used only when applications depend on the old behavior.
Link: None
Trace Flag: 1610
Function: Boot the SQL dataserver with TCP_NODELAY enabled
Link: None
Trace Flag: 1611
Function: If possible, pin shared memory -- check errorlog for success/failure
Link: None
Trace Flag: 1613
Function: Set affinity of the SQL data server engine's onto particular CPUs -- usually pins engine 0 to processor 0, engine 1 to processor 1...
Link: None
Trace Flag: 1615
Function: Khen2005, page 385 (paraphrased): directs SQL to use threads instead of fiber even if the “lightweight pooling” config option is on. (Apparently, sometimes SQL wouldn’t start successfully when using lightweight pooling, and so this lets you get SQL up and running, so that you can turn the config option off)
Link: None
Trace Flag: 1704
Function: Prints information when a temporary table is created or dropped
Link: None
Trace Flag: 1717
Function: MSShipped bit will be set automatically at Create time when creating stored procedures
Link: None
Trace Flag: 1800
Function: Enables SQL Server optimization when disks of different sector sizes are used for primary and secondary replica log files, in SQL Server AG and Log Shipping environments.
Link: https://support.microsoft.com/en-us/kb/3009974
Link: MSDN ms188396
Scope: global only
Trace Flag: 1802
Function: SQL 9 - After detaching a database that resides on network-attached storage, you cannot reattach the SQL Server database
Link: https://support.microsoft.com/en-us/kb/922804
Trace Flag: 1806
Function: Disable Instant File Initialization
Link: http://technet.microsoft.com/en-au/library/cc917726.aspx Link: https://blogs.msdn.microsoft.com/sql_pfe_blog/2009/12/22/how-and-why-to-enable-instant-file-initialization Link: http://www.sqlskills.com/blogs/paul/a-sql-server-dba-myth-a-day-330-instant-file-initialization-can-be-controlled-from-within-sql-server Link: https://support.microsoft.com/en-us/help/2574695/file-initialization-takes-a-long-time-for-sql-server-database-related-operations
Trace Flag: 1807
Function: Enable option to have database files on SMB share for SQL Server 2008 and 2008R2
Link: http://blogs.msdn.com/b/varund/archive/2010/09/02/create-a-sql-server-database-on-a-network-shared-drive.aspx Link: https://support.microsoft.com/en-us/help/304261/description-of-support-for-network-database-files-in-sql-server
Trace Flag: 1808
Function: Directs SQL Server to ignore auto-closing databases even if the Auto-close property is set to ON. Must be set globally. Present in Yukon forward
Link: https://blogs.msdn.microsoft.com/ialonso/2012/04/11/want-your-sql-server-to-simply-ignore-the-auto_close-setting-for-all-open-databases-for-which-it-has-been-enabled
Trace Flag: 1810
Function: Prints the file create/open/close timings
Link: None
Trace Flag: 1816
Function: Bob Ward briefly references this flag in his PASS 2014 SQL Server IO talk, saying that it “could provide more details around errors” that occur with IO done to SQL data files in Azure Storage.
Link: None
Trace Flag: 1903
Function: SQL 8 - When you capture a SQL Profiler trace in a file and then you try to import the trace files into tables by using the fn_trace_gettable function no rows may be returned
Link: https://support.microsoft.com/en-us/kb/911678
Trace Flag: 2301
Function: Enable advanced decision support optimizations
Link: KB920093
Link: MSDN ms188396
Scope: global and session and query
Trace Flag: 2312
Function: Enables you to set the query optimizer cardinality estimation model to the SQL Server 2014 through SQL Server 2016 versions, dependent of the compatibility level of the database.
Link: KB2801413
Link: New Features in SQL Server 2016 Service Pack 1
Link: MSDN ms188396
Scope: global or session or query
Trace Flag: 2328
Function: SQL 9+ - Makes cardinality estimates upon resulting selectivity. The reasoning for this is that one or more of the constants may be statement parameters, which would change from one execution of the statement to the next.
Link: None
Trace Flag: 2330
Function: Query performance decreases when sys.dm_db_index_usage_stats has large number of rows
Link: http://www.brentozar.com/archive/2015/11/trace-flag-2330-who-needs-missing-index-requests/ Link: https://chrisadkin.org/2015/04/14/well-known-and-not-so-well-known-sql-server-tuning-knobs-and-switches/
Trace Flag: 2335
Function: Causes SQL Server to assume a fixed amount of memory is available during query optimization. It does not limit the memory SQL Server grants to execute the query. The memory configured for SQL Server will still be used by data cache, query execution and other consumers.
Note: Please ensure that you thoroughly test this option, before rolling it into a production environment.
Link: https://support.microsoft.com/en-us/kb/2413549
Link: MSDN ms188396
Scope: global or session or query
Trace Flag: 2340
Function: Causes SQL Server not to use a sort operation (batch sort) for optimized nested loop joins when generating a plan. Beginning with SQL Server 2016 SP1, to accomplish this at the query level, add the USE HINT query hint instead of using this trace flag.
Note: Please ensure that you thoroughly test this option, before rolling it into a production environment.
Link: https://support.microsoft.com/en-us/kb/2009160
Link: New Features in SQL Server 2016 Service Pack 1
Link: MSDN ms188396
Scope: global or session or query
Trace Flag: 2363
Function: TF Selectivity
Link: Cardinality Estimation Framework 2014 First Look
Link: http://www.queryprocessor.com/ce-process/
Trace Flag: 2371
Function: Changes the fixed auto update statistics threshold to dynamic auto update statistics threshold.
Note: Beginning with SQL Server 2016 this behavior is controlled by the engine and trace flag 2371 has no effect.
Link: http://www.sqlservice.se/sv/start/blogg/sql-server--auto-update-stats-part-2.aspx
Link: https://support.microsoft.com/en-us/kb/2754171
Link: http://blogs.msdn.com/b/saponsqlserver/archive/2011/09/07/changes-to-automatic-update-statistics-in-sql-server-traceflag-2371.aspx
Link: MSDN ms188396
Scope: global only
Trace Flag: 2372
Function: Displays memory utilization during the optimization process. Memory for Phases.
Link: More Undocumented Query Optimizer Trace Flags
Link: