First drafts of LockAndWait and TranLogRecov

cat/db_LockAndWait.rst

@@ -1,3 +1,332 @@
 ===================
 Locking and Waiting
-===================
+===================
+
+Flags in this category fall into the below groupings:
+
+#. `Informational`_ --> Flags that return info about locks and deadlocks.
+#. `Functionality Toggles`_ --> Flags that modify lock escalation or other locking behaviors.
+#. `Fixes and Past Relevance`_ --> Fix flags and flags which are no longer relevant.
+
+
+See also: 
+
+1229 prob needs a See Also in the scheduler section.
+
+Is 8755 already referenced in the query optimization section? 
+
+|
+
+
+Short Descriptions
+------------------
+
+.. This comment line is as long as we would ever want the short desc to be in the table below.
+
+.. list-table::
+	:widths: 10 60
+	:header-rows: 1
+
+	* - Flag
+	  - Short Description
+	* - See Also
+	  - 
+	* - :doc:`205 <qry_CompInfo>`
+	  - Reports to error log when recompile occurs due to auto-update of stats.
+	* - ...
+	  - 
+	* - :ref:`Info <InfoBakRes>`
+	  - 
+	* - 611_
+	  - Records lock escalations in the SQL error log.
+	* - 1200_
+	  - Prints detailed lock info for every lock request/release.
+	* - \* 1204_
+	  - Prints detailed info upon every deadlock occurrence.
+	* - 1205_
+	  - Prints info to SQL error log every time a deadlock search begins.
+	* - 1206_
+	  - Complements 1204 by printing other locks held by deadlock parties.
+	* - 1208_
+	  - Prints host name/program name [by clients in a deadlock?]
+	* - 1222_
+	  - Similar to 1204, but with more info and in an XML format.
+	* - 8001_
+	  - Adds more wait types to sys.dm_os_wait_stats
+	* - 8050_
+	  - Removes "optional" wait types from sys.dm_os_wait_stats.
+	* - ...
+	  - 
+	* - :ref:`Func <FuncBakRes>`
+	  - 
+	* - \* 1211_
+	  - Disables lock escalations due to memory pressure.
+	* - \* 1224_
+	  - Disables lock escalations based on number of locks.
+	* - 1229_
+	  - Disables lock partitioning among schedulers.
+	* - 8755_
+	  - Disables any locking hints in query text.
+	* - ...
+	  - 
+	* - :ref:`Fix/PastRel <FixPastRel7>`
+	  - 
+	* - 1216_
+	  - Complicated; see below
+	* - 1236_
+	  - Reduces LOCK_HASH spinlock contention on older builds
+	* - 2456_
+	  - Relieves RESOURCE_SEMAPHORE_MUTEX contention in SQL 2005.
+
+.. This comment line is as long as we would ever want the short desc to be in the table above.
+
+|
+
+.. _InfoLockWait:
+
+Informational
+-------------
+
+.. _611:
+
+611 (Info)
+	Records each lock escalation, in 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"
+
+	Aaron: Confirmed still in SQL 2014. 
+
+	SSWUG_1_
+
+
+.. _1200:	
+
+1200
+	Prints detailed lock info as every request for a lock is made (the process ID and type of 
+	lock requested).
+
+	169960_ | StorEng_1_ (comments)
+
+
+.. _1204:	
+
+1204 ``Doc2005`` (Info)
+	`BOL 2014`_: "Returns the resources and types of locks participating in a deadlock and 
+	also the current command affected.". 
+
+	937950 notes a specific type of error where 1204 will not help with deadlocks.
+
+	832524_ | 937950_ 
+
+
+.. _1205:
+
+1205 (Info)
+	Prints information to the SQL error log every time a deadlock search starts, 
+	whether or not a deadlock is found.
+
+	832524_
+
+
+.. _1206:
+
+1206 (Info)
+	Used to complement flag 1204 by displaying other locks held by deadlock parties.
+
+	169960_
+
+
+.. _1208:
+
+1208 (Info)
+	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." 
+
+	169960_
+
+
+.. _1222:
+
+1222 ``Doc2005`` (Info) 
+	`BOL 2014`_: "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."
+
+
+.. _8001:
+
+8001 (Info)
+	Khen2005, p2: "For SQL Server 2005, the SQL Server product team opted not to include 
+	[in sys.dm_os_wait_stats] some wait types that fall under one of the following three 
+	categories:
+		-	Wait types that are never used in SQL Server 2005; note that some wait types not excluded are also never used.
+		-	Wait types that can occur only at times when they do not affect user activity, such as during initial server startup and shutdown, and are not visible to users.
+		-	Wait types that are innocuous but have caused concern among users because of their high occurrence or duration
+
+	The complete list of wait types is available by enabling trace flag 8001. The only effect 
+	of this trace flag is to force sys.dm_os_wait_stats to display all wait types."
+
+
+.. _8050:
+
+8050 (Info)
+	Causes "optional" wait types (see the CSS article) to be excluded when querying sys.dm_os_wait_stats.
+
+	CSS_2_
+
+
+|
+
+.. _FuncLockWait: 
+
+Functionality Toggles
+---------------------
+
+.. _1211:
+
+1211 ``Doc2005``
+	`BOL 2014`_: "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."
+
+	PRand_1_
+
+
+.. _1224:
+
+1224 ``Doc2005``
+	`BOL 2014`_: "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.
+
+	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."
+
+	PRand_1_
+
+
+.. _1229:
+
+1229
+	Disables lock partitioning (among schedulers).
+
+	CSS_1_ 
+
+
+.. _8755:
+
+8755
+	Disables any locking hints and permits the optimizer/query execution engine to select 
+	the appropriate lock behavior.
+
+	SQLMag_1_
+
+
+
+
+|
+
+.. _FixPastRel8:
+
+Fixes and Past Relevance
+------------------------
+These flags either are old and irrelevant for modern builds, appear only in CTPs, or enable a 
+fix in a CU but are baselined in a later service pack or release.
+
+.. _1216:
+
+1216 (Info?)
+	319892: mentions 1216 in passing as a flag in SQL 2000 that is associated with 
+	deadlock output. The mention occurs only to distance TF1216 on SQL 2000 from TF 1216 
+	on SQL 7.0 and TF 1261 on SQL 2000, which both have a different purpose than 1216 on 
+	SQL 2000. Prob needs to be tested on modern versions.
+
+	319892_
+
+
+.. _1236:
+
+1236
+	(On by default in SQL 2014 SP1+ and SQL 2012 SP3) Partitions the DATABASE lock type to 
+	help reduce contention on internal locking structures symptomized by LOCK_HASH spinlock 
+	contention.
+
+	2926217_
+
+
+.. _2456:
+
+2456
+	Relieves RESOURCE_SEMAPHORE_MUTEX contention, which may be primarily due to a bug in 
+	SQL 2005.
+
+	956375_
+
+
+
+
+
+.. Official Links 
+
+.. _BOL 2008: https://technet.microsoft.com/en-us/library/ms188396(v=sql.100).aspx
+
+.. _BOL 2014: https://technet.microsoft.com/en-us/library/ms188396.aspx
+
+.. _BOL 2016: https://technet.microsoft.com/en-us/library/ms188396.aspx
+
+.. _169960: http://support.microsoft.com/kb/169960/en-us
+
+.. _2926217: http://support.microsoft.com/kb/2926217
+
+.. _319892: http://support.microsoft.com/kb/319892
+
+.. _832524: http://support.microsoft.com/kb/832524
+
+.. _956375: http://support.microsoft.com/kb/956375/en-us
+
+.. _937950: http://support.microsoft.com/kb/937950/en-us
+
+
+.. MSFT Blog links
+
+.. _CSS_1: http://blogs.msdn.com/b/psssql/archive/2012/08/31/strange-sch-s-sch-m-deadlock-on-machines-with-16-or-more-schedulers.aspx
+
+.. _CSS_2: http://blogs.msdn.com/b/psssql/archive/2009/11/03/the-sql-server-wait-type-repository.aspx
+
+.. _StorEng_1: http://blogs.msdn.com/b/sqlserverstorageengine/archive/2008/03/30/sql-server-table-variable-vs-local-temporary-table.aspx
+
+
+
+.. Non-MSFT bloggers
+
+.. _PRand_1: http://www.sqlskills.com/blogs/paul/a-sql-server-dba-myth-a-day-2330-lock-escalation/
+
+
+.. Connect links
+
+
+.. Forums 
+
+
+.. Other Links 
+
+.. _SSWUG_1: http://www.sswug.org/articles/viewarticle.aspx?id=undocumented_sql_server_2005_trace_flags-27595
+
+.. _SQLMag_1: http://sqlmag.com/sql-server/investigating-trace-flags