Merge branch 'master' of https://github.com/MicrosoftDocs/sql-docs-pr into release-2019-cu

Author: v-alje

docs/database-engine/configure-windows/affinity-mask-server-configuration-option.md

@@ -120,13 +120,13 @@ These are **affinity mask** values for an 8-CPU system.
 
 The affinity mask option is an advanced option. If you're using the sp_configure system stored procedure to change the setting, you can change **affinity mask** only when **show advanced options** is set to 1. After executing the [!INCLUDE[tsql](../../includes/tsql-md.md)] RECONFIGURE command, the new setting takes effect immediately without requiring a restart of the SQL Server instance.  
 
-## Non-uniform Memory Access (NUMA)
+## Non-uniform memory access (NUMA)
 
 When using hardware-based non-uniform memory access (NUMA) and the affinity mask is set, every scheduler in a node binds to its own CPU. When the affinity mask isn't set, each scheduler is bound to the group of CPUs within the NUMA node and a scheduler mapped to NUMA node N1 can schedule work on any CPU in the node, but not on CPUs associated with another node.  
 
 Any operation running on a single NUMA node can only use buffer pages from that node. When an operation is run in parallel on CPUs from multiple nodes, memory can be used from any node involved.  
 
-## Licensing Issues
+## Licensing issues
 
 Dynamic affinity is tightly constrained by CPU licensing. SQL Server doesn't allow any configuration of 
 affinity mask options that violates the licensing policy.  

docs/relational-databases/security/encryption/sql-server-connector-maintenance-troubleshooting.md

@@ -141,9 +141,9 @@ If the vault has been lost, you will need to recreate a vault and restore the as
 
 In summary, here are the steps:  
   
-* Back up the vault key (using the Backup-AzureKeyVaultKey Powershell cmdlet).  
+* Back up the vault key (using the Backup-AzureKeyVaultKey PowerShell cmdlet).  
 * In the case of vault failure, create a new vault in the same geographic region*. The user creating this should be in the same default directory as the service principal setup for SQL Server.  
-* Restore the key to the new vault (using the Restore-AzureKeyVaultKey Powershell cmdlet - this restores the key using the same name as before). If there is already a key with the same name, the restore will fail.  
+* Restore the key to the new vault (using the Restore-AzureKeyVaultKey PowerShell cmdlet - this restores the key using the same name as before). If there is already a key with the same name, the restore will fail.  
 * Grant permissions to the SQL Server service principal to use this new vault.  
 * Modify the SQL Server credential used by the Database Engine to reflect the new vault name (if needed).  
   
@@ -162,7 +162,7 @@ Key backups can be restored across Azure regions, as long as they remain in the
 ### On Configuring [!INCLUDE[ssNoVersion](../../../includes/ssnoversion-md.md)]  
 
 **What are the endpoints that the SQL Server Connector needs access to?** 
- The Connector talks to two endpoints, which need to be whitelisted. The only port required for outbound communication to these other services is 443 for Https:
+ The Connector talks to two endpoints, which need to be allowed. The only port required for outbound communication to these other services is 443 for Https:
 -  login.microsoftonline.com/*:443
 -  *.vault.azure.net/*:443
 
@@ -211,7 +211,7 @@ Error code  |Symbol  |Description
 5 | scp_err_AuthFailure | The authentication has failed with EKM provider.    
 6 | scp_err_InvalidArgument | The provided argument is invalid.    
 7 | scp_err_ProviderError | There is an unspecified error happened in EKM provider that is caught by SQL engine.   
-401 | acquireToken | Server responded 401 for the request. Make sure the client Id and secret are correct, and the credential string is a concatenation of AAD client Id and secret without hyphens.
+401 | acquireToken | Server responded 401 for the request. Make sure the client ID and secret are correct, and the credential string is a concatenation of AAD client ID and secret without hyphens.
 404 | getKeyByName | The server responded 404, because the key name was not found. Please make sure the key name exists in your vault.
 2049 | scp_err_KeyNameDoesNotFitThumbprint | The key name is too long to fit into SQL engine's thumbprint. The key name must not exceed 26 characters.    
 2050 | scp_err_PasswordTooShort | The secret string that is the concatenation of AAD client ID and secret is shorter than 32 characters.    
@@ -251,7 +251,7 @@ If you don't see your error code in this table, here are some other reasons the
   
 -   If you receive a "Cannot load library" error, make sure you have the appropriate version of the Visual Studio C++ redistributable installed based on the version of SQL Server that you are running. The table below specifies which version to install from the Microsoft Download Center.   
 
-The Windows event log also logs errors associated with the SQL Server Connnector, which can help with additional context on why the error is actually happening. The source in the Windows Application Event Log will be "SQL Server Connector for Microsoft Azure Key Vault".
+The Windows event log also logs errors associated with the SQL Server Connector, which can help with additional context on why the error is actually happening. The source in the Windows Application Event Log will be "SQL Server Connector for Microsoft Azure Key Vault".
   
 SQL Server Version  |Redistributable Install Link    
 ---------|--------- 

docs/relational-databases/statistics/statistics.md

@@ -1,7 +1,7 @@
 ---
 title: "Statistics | Microsoft Docs"
 ms.custom: ""
-ms.date: "12/18/2017"
+ms.date: "06/03/2020"
 ms.prod: sql
 ms.reviewer: ""
 ms.technology: performance
@@ -131,7 +131,11 @@ For more information about controlling AUTO_UPDATE_STATISTICS, see [Controlling
 * Your application frequently executes the same query, similar queries, or similar cached query plans. Your query response times might be more predictable with asynchronous statistics updates than with synchronous statistics updates because the Query Optimizer can execute incoming queries without waiting for up-to-date statistics. This avoids delaying some queries and not others.  
 
 * Your application has experienced client request time outs caused by one or more queries waiting for updated statistics. In some cases, waiting for synchronous statistics could cause applications with aggressive time outs to fail.  
-  
+
+Asynchronous statistics update is performed by a background request. When the request is ready to write updated statistics to the database, it attempts to acquire a schema modification lock on the statistics metadata object. If a different session is already holding a lock on the same object, asynchronous statistics update is blocked until the schema modification lock can be acquired. Similarly, sessions that need to acquire a schema stability lock on the statistics metadata object to compile a query may be blocked by the asynchronous statistics update background session, which is already holding or waiting to acquire the schema modification lock. Therefore, for workloads with very frequent query compilations and frequent statistics updates, using asynchronous statistics may increase the likelihood of concurrency issues due to lock blocking.
+
+In Azure SQL Database, you can avoid potential concurrency issues using asynchronous statistics update if you enable the ASYNC_STATS_UPDATE_WAIT_AT_LOW_PRIORITY [database-scoped configuration](../../t-sql/statements/alter-database-scoped-configuration-transact-sql.md). With this configuration enabled, the background request will wait to acquire the schema modification lock on a separate low priority queue, allowing other requests to continue compiling queries with existing statistics. Once no other session is holding a lock on the statistics metadata object, the background request will acquire its schema modification lock and update statistics. In the unlikely event that the background request cannot acquire the lock within a timeout period of several minutes, the asynchronous statistics update will be aborted, and the statistics will not be updated until another automatic statistics update is triggered, or until statistics are [updated manually](update-statistics.md).
+
 #### INCREMENTAL  
  When INCREMENTAL option of CREATE STATISTICS is ON, the statistics created are per partition statistics. When OFF, the statistics tree is dropped and [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] re-computes the statistics. The default is OFF. This setting overrides the database level INCREMENTAL property. For more information about creating incremental statistics, see [CREATE STATISTICS (Transact-SQL)](../../t-sql/statements/create-statistics-transact-sql.md). For more information about creating per partition statistics automatically, see [Database Properties (Options Page)](../../relational-databases/databases/database-properties-options-page.md#automatic) and [ALTER DATABASE SET Options (Transact-SQL)](../../t-sql/statements/alter-database-transact-sql-set-options.md). 
 

docs/t-sql/statements/alter-database-scoped-configuration-transact-sql.md

@@ -31,7 +31,7 @@ monikerRange: "= azuresqldb-current || = azuresqldb-mi-current || >= sql-server-
 
 This command enables several database configuration settings at the **individual database** level. 
 
-Following settings are supported in [!INCLUDE[sssdsfull](../../includes/sssdsfull-md.md)] and in [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] beginning with [!INCLUDE[ssSQL15](../../includes/sssql15-md.md)]: 
+Following settings are supported in [!INCLUDE[sssdsfull](../../includes/sssdsfull-md.md)] and in [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] as indicated by the **APPLIES TO** line for each setting in the [Arguments](#arguments) section: 
 
 - Clear procedure cache.
 - Set the MAXDOP parameter to an arbitrary value (1,2, ...) for the primary database based on what works best for that particular database and set a different value (such as 0) for all secondary database used (such as for reporting queries).
@@ -50,6 +50,7 @@ Following settings are supported in [!INCLUDE[sssdsfull](../../includes/sssdsful
 - Enable or disable the new `String or binary data would be truncated` error message.
 - Enable or disable collection of last actual execution plan in [sys.dm_exec_query_plan_stats](../../relational-databases/system-dynamic-management-views/sys-dm-exec-query-plan-stats-transact-sql.md).
 - Specify the number of minutes that a paused resumable index operation is paused before it is automatically aborted by the SQL Server engine.
+- Enable or disable waiting for locks at low priority for asynchronous statistics update
 
 This setting is only available in Azure Synapse Analytics (Formerly SQL DW).
 - Set the compatibility level of a user database
@@ -95,6 +96,7 @@ ALTER DATABASE SCOPED CONFIGURATION
     | LAST_QUERY_PLAN_STATS = { ON | OFF }
     | PAUSED_RESUMABLE_INDEX_ABORT_DURATION_MINUTES = <time>
     | ISOLATE_SECURITY_POLICY_CARDINALITY  = { ON | OFF }
+    | ASYNC_STATS_UPDATE_WAIT_AT_LOW_PRIORITY = { ON | OFF }
 }
 ```
 
@@ -104,8 +106,8 @@ ALTER DATABASE SCOPED CONFIGURATION
 > -  `DISABLE_BATCH_MODE_MEMORY_GRANT_FEEDBACK` changed to `BATCH_MODE_MEMORY_GRANT_FEEDBACK`
 > -  `DISABLE_BATCH_MODE_ADAPTIVE_JOINS` changed to `BATCH_MODE_ADAPTIVE_JOINS`
 
-```syntaxsql
--- Synatx for Azure Synapse Analytics (Formerly SQL DW)
+```SQL
+-- Syntax for Azure Synapse Analytics (Formerly SQL DW)
 
 ALTER DATABASE SCOPED CONFIGURATION
 {
@@ -404,6 +406,12 @@ Sets Transact-SQL and query processing behaviors to be compatible with the speci
 |**10**| Exercises the Transact-SQL and query processing behaviors before the introduction of compatibility level support.|
 |**20**| 1st compatibility level that includes gated Transact-SQL and query processing behaviors. |
 
+ASYNC_STATS_UPDATE_WAIT_AT_LOW_PRIORITY **=** { ON | **OFF**}
+
+**APPLIES TO**: Azure SQL Database only (feature is in public preview)
+
+If asynchronous statistics update is enabled, enabling this configuration will cause the background request updating statistics to wait for a Sch-M lock on a low priority queue, to avoid blocking other sessions in high concurrency scenarios. For more information, see [AUTO_UPDATE_STATISTICS_ASYNC](../../relational-databases/statistics/statistics.md#auto_update_statistics_async).
+
 ## <a name="Permissions"></a> Permissions
 
 Requires `ALTER ANY DATABASE SCOPED CONFIGURATION` on the database. This permission can be granted by a user with CONTROL permission on a database.
@@ -414,7 +422,7 @@ While you can configure secondary databases to have different scoped configurati
 
 Executing this statement clears the procedure cache in the current database, which means that all queries have to recompile.
 
-For 3-part name queries, the settings for the current database connection for the query are honored, other than for SQL modules (such as procedures, functions, and triggers) that are compiled in the current database context and therefore uses the options of the database in which they reside.
+For 3-part name queries, the settings for the current database connection for the query are honored, other than for SQL modules (such as procedures, functions, and triggers) that are compiled in another database context and therefore use the options of the database in which they reside. Similarly, when updating statistics asynchronously, the setting of ASYNC_STATS_UPDATE_WAIT_AT_LOW_PRIORITY for the database where statistics reside is honored.
 
 The `ALTER_DATABASE_SCOPED_CONFIGURATION` event is added as a DDL event that can be used to fire a DDL trigger, and is a child of the `ALTER_DATABASE_EVENTS` trigger group.