Replication Snapshot Agent
Applies to: 
SQL Server
Azure SQL Database
The Replication Snapshot Agent is an executable file that prepares snapshot files containing schema and data of published tables and database objects, stores the files in the snapshot folder, and records synchronization jobs in the distribution database.
Note
- Parameters can be specified in any order.
Note
Azure SQL Managed Instance can be a publisher, distributor, and subscriber for snapshot and transactional replication. Databases in Azure SQL Database can only be push subscribers for snapshot and transactional replication. For more information, see Transactional replication with Azure SQL Database and Azure SQL Managed Instance.
Syntax
snapshot [ -?]
-Publisher server_name[\instance_name]
-Publication publication_name
[-70Subscribers]
[-BcpBatchSize bcp_batch_size]
[-DefinitionFile def_path_and_file_name]
[-Distributor server_name[\instance_name]]
[-DistributorDeadlockPriority [-1|0|1] ]
[-DistributorLogin distributor_login]
[-DistributorPassword distributor_password]
[-DistributorSecurityMode [0|1] ]
[-DynamicFilterHostName dynamic_filter_host_name]
[-DynamicFilterLogin dynamic_filter_login]
[-DynamicSnapshotLocation dynamic_snapshot_location]
[-EncryptionLevel [0|1|2]]
[-FieldDelimiter field_delimiter]
[-HistoryVerboseLevel [0|1|2|3] ]
[-HRBcpBlocks number_of_blocks ]
[-HRBcpBlockSize block_size ]
[-HRBcpDynamicBlocks ]
[-KeepAliveMessageInterval keep_alive_interval]
[-LoginTimeOut login_time_out_seconds]
[-MaxBcpThreads number_of_threads ]
[-MaxNetworkOptimization [0|1]]
[-Output output_path_and_file_name]
[-OutputVerboseLevel [0|1|2] ]
[-PacketSize packet_size]
[-PrefetchTables [0|1] ]
[-ProfileName profile_name]
[-PublisherDB publisher_database]
[-PublisherDeadlockPriority [-1|0|1] ]
[-PublisherFailoverPartner server_name[\instance_name] ]
[-PublisherLogin publisher_login]
[-PublisherPassword publisher_password]
[-PublisherSecurityMode [0|1] ]
[-QueryTimeOut query_time_out_seconds]
[-ReplicationType [1|2] ]
[-RowDelimiter row_delimiter]
[-StartQueueTimeout start_queue_timeout_seconds]
[-UsePerArticleContentsView use_per_article_contents_view]
Arguments
-?
Prints all available parameters.
-Publisher server_name[\instance_name]
Is the name of the Publisher. Specify server_name for the default instance of Microsoft SQL Server on that server. Specify server_name\instance_name for a named instance of SQL Server on that server.
-Publication publication
Is the name of the publication. This parameter is only valid if the publication is set to always have a snapshot available for new or reinitialized subscriptions.
-70Subscribers
Must be used if any Subscribers are running SQL Server version 7.0.
-BcpBatchSize bcp_ batch_ size
Is the number of rows to send in a bulk copy operation. When performing a bcp in operation, the batch size is the number of rows to send to the server as one transaction, and also the number of rows that must be sent before the Distribution Agent logs a bcp progress message. When performing a bcp out operation, a fixed batch size of 1000 is used. A value of 0 indicates no message logging.
-DefinitionFile def_path_and_file_name
Is the path of the agent definition file. An agent definition file contains command line arguments for the agent. The content of the file is parsed as an executable file. Use double quotation marks (") to specify argument values containing arbitrary characters.
-Distributor server_name[\instance_name]
Is the Distributor name. Specify server_name for the default instance of SQL Server on that server. Specify server_name\instance_name for a named instance of SQL Server on that server.
-DistributorDeadlockPriority [-1|0|1]
Is the priority of the Snapshot Agent connection to the Distributor when a deadlock occurs. This parameter is specified to resolve deadlocks that may occur between the Snapshot Agent and user applications during snapshot generation.
| DistributorDeadlockPriority value | Description |
|---|---|
| -1 | Applications other than the Snapshot Agent have priority when a deadlock occurs at the Distributor. |
| 0 (Default) | Priority is not assigned. |
| 1 | Snapshot Agent has priority when a deadlock occurs at the Distributor. |
-DistributorLogin distributor_login
Is the login used when connecting to the Distributor using SQL Server Authentication.
-DistributorPassword distributor_password
Is the password used when connecting to the Distributor using SQL Server Authentication. .
-DistributorSecurityMode [ 0| 1]
Specifies the security mode of the Distributor. A value of 0 indicates SQL Server Authentication Mode (default), and a value of 1 indicates Windows Authentication Mode.
-DynamicFilterHostName dynamic_filter_host_name
Is used to set a value for HOST_NAME (Transact-SQL) in filtering when a dynamic snapshot is created. For example, if the subset filter clause rep_id = HOST_NAME() is specified for an article, and you set the DynamicFilterHostName property to "FBJones" before calling the Merge Agent, only rows having "FBJones" in the rep_id column will be replicated.
-DynamicFilterLogin dynamic_filter_login
Is used to set a value for SUSER_SNAME (Transact-SQL) in filtering when a dynamic snapshot is created. For example, if the subset filter clause user_id = SUSER_SNAME() is specified for an article, and you set the DynamicFilterLogin property to "rsmith" before calling the Run method of the SQLSnapshot object, only rows having "rsmith" in the user_id column will be included in the snapshot.
-DynamicSnapshotLocation dynamic_snapshot_location
Is the location where the dynamic snapshot should be generated.
-EncryptionLevel [ 0 | 1 | 2 ]
Is the level of Transport Layer Security (TLS), previously known as Secure Sockets Layer (SSL), encryption used by the Snapshot Agent when making connections.
| EncryptionLevel value | Description |
|---|---|
| 0 | Specifies that TLS is not used. |
| 1 | Specifies that TLS is used, but the agent does not verify that the TLS/SSL server certificate is signed by a trusted issuer. |
| 2 | Specifies that TLS is used, and that the certificate is verified. |
Note
A valid TLS/SSL certificate is defined with a fully qualified domain name of the SQL Server. In order for the agent to connect successfully when setting -EncryptionLevel to 2, create an alias on the local SQL Server. The 'Alias Name' parameter should be the server name and the 'Server' parameter should be set to the fully qualified name of the SQL Server.
For more information, see View and modify replication security settings.
-FieldDelimiter field_delimiter
Is the character or character sequence that marks the end of a field in the SQL Server bulk-copy data file. The default is \n<x$3>\n.
-HistoryVerboseLevel [ 1| 2| 3]
Specifies the amount of history logged during a snapshot operation. You can minimize the effect of history logging on performance by selecting 1.
| HistoryVerboseLevel value | Description |
|---|---|
| 0 | Progress messages are written either to the console or to an output file. History records are not logged in the distribution database. |
| 1 | Always update a previous history message of the same status (startup, progress, success, and so on). If no previous record with the same status exists, insert a new record. |
| 2 (default) | Insert new history records unless the record is for such things as idle messages or long-running job messages, in which case update the previous records. |
| 3 | Always insert new records, unless it is for idle messages. |
-HRBcpBlocks number_of_blocks
Is the number of bcp data blocks that are queued between the writer and reader threads. The default value is 50. HRBcpBlocks is only used with Oracle publications.
Note
This parameter is used for performance tuning of bcp performance from an Oracle Publisher.
-HRBcpBlockSizeblock_size
Is the size, in kilobytes (KB), of each bcp data block. The default value is 64 KB. HRBcpBlocks is only used with Oracle publications.
Note
This parameter is used for performance tuning of bcp performance from an Oracle Publisher.
-HRBcpDynamicBlocks
Is whether or not the size of each bcp data block can grow dynamically. HRBcpBlocks is only used with Oracle publications.
Note
This parameter is used for performance tuning of bcp performance from an Oracle Publisher.
-KeepAliveMessageInterval keep_alive_interval
Is the amount of time, in seconds, that the Snapshot Agent waits before logging "waiting for backend message" to the MSsnapshot_history table. The default value is 300 seconds.
-LoginTimeOut login_time_out_seconds
Is the number of seconds before the login times out. The default is 15 seconds.
-MaxBcpThreads number_of_threads
Specifies the number of bulk copy operations that can be performed in parallel. The maximum number of threads and ODBC connections that exist simultaneously is the lesser of MaxBcpThreads or the number of bulk copy requests that appear in the synchronization transaction in the distribution database. MaxBcpThreads must have a value greater than 0 and has no hard-coded upper limit. The default is twice the number of processors.
Note
If the replicated object has a filter, then the Snapshot agent will generate only one BCP file for that article instead of generating multiple BCP files.
- MaxNetworkOptimization [ 0| 1]
Is if irrelevant deletes are sent to the Subscriber. Irrelevant deletes are DELETE commands that are sent to Subscribers for rows that do not belong to the Subscriber's partition. Irrelevant deletes do not affect data integrity or convergence, but they can result in unnecessary network traffic. The default value of MaxNetworkOptimization is 0. Setting MaxNetworkOptimization to 1 minimizing the chances of irrelevant deletes thereby reducing network traffic and maximizing network optimization. Setting this parameter to 1 can also increase the storage of metadata and cause performance to degrade at the Publisher if multiple levels of join filters and complex subset filters are present. You should carefully assess your replication topology and set MaxNetworkOptimization to 1 only if network traffic from irrelevant deletes is unacceptably high.
Note
Setting this parameter to 1 is useful only when the synchronization optimization option of the merge publication is set to true (the @keep_partition_changes** parameter of sp_addmergepublication (Transact-SQL)).
-Output output_path_and_file_name
Is the path of the agent output file. If the file name is not provided, the output is sent to the console. If the specified file name exists, the output is appended to the file.
-OutputVerboseLevel [ 0| 1| 2]
Specifies whether the output should be verbose.
| OutputVerboseLevel value | Description |
|---|---|
| 0 | Only error messages are printed. |
| 1 (default) | All the progress report messages are printed (default). |
| 2 | All error messages and progress report messages are printed, which is useful for debugging. |
-PacketSize packet_size
Is the packet size (in bytes) used by the Snapshot Agent when connecting to SQL Server. The default value is 8192 bytes.
Note
Do not change the packet size unless you are certain that it will improve performance. For most applications, the default packet size is best.
-PrefetchTables [ 0| 1]
Optional parameter that specifies if the table objects will be prefetched and cached. The default behavior is to prefetch certain table properties using SMO component based on an internal calculation. This parameter can be helpful in scenarios where SMO prefetch operation takes considerable longer to run. If this parameter is not used, this decision is made at runtime based on the percentage of tables that are added as articles to the publication.
| OutputVerboseLevel value | Description |
|---|---|
| 0 | Call to Prefetch method of SMO component is disabled. |
| 1 | Snapshot Agent will call Prefetch method to cache some table properties using SMO |
-ProfileName profile_name
Specifies an agent profile to use for agent parameters. If ProfileName is NULL, the agent profile is disabled. If ProfileName is not specified, the default profile for the agent type is used. For information, see Replication Agent Profiles.
-PublisherDB publisher_database
Is the name of the publication database. This parameter is not supported for Oracle Publishers.
-PublisherDeadlockPriority [-1|0|1]
Is the priority of the Snapshot Agent connection to the Publisher when a deadlock occurs. This parameter is specified to resolve deadlocks that may occur between the Snapshot Agent and user applications during snapshot generation.
| PublisherDeadlockPriority value | Description |
|---|---|
| -1 | Applications other than the Snapshot Agent have priority when a deadlock occurs at the Publisher. |
| 0 (Default) | Priority is not assigned. |
| 1 | Snapshot Agent has priority when a deadlock occurs at the Publisher. |
-PublisherFailoverPartner server_name[\instance_name]
Specifies the failover partner instance of SQL Server participating in a database mirroring session with the publication database. For more information, see Database Mirroring and Replication (SQL Server).
-PublisherLogin publisher_login
Is the login used when connecting to the Publisher using SQL Server Authentication.
-PublisherPassword publisher_password
Is the password used when connecting to the Publisher using SQL Server Authentication. .
-PublisherSecurityMode [ 0| 1]
Specifies the security mode of the Publisher. A value of 0 indicates SQL Server Authentication (default), and a value of 1 indicates Windows Authentication Mode.
-QueryTimeOut query_time_out_seconds
Is the number of seconds before the query times out. The default is 1800 seconds.
-ReplicationType [ 1| 2]
Specifies the type of replication. A value of 1 indicates transactional replication, and a value of 2 indicates merge replication.
-RowDelimiter row_delimiter
Is the character or character sequence that marks the end of a row in the SQL Server bulk-copy data file. The default is \n<,@g>\n.
-StartQueueTimeout start_queue_timeout_seconds
Is the maximum number of seconds that the Snapshot Agent waits when the number of concurrent dynamic snapshot processes running is at the limit set by the @max_concurrent_dynamic_snapshots property of sp_addmergepublication (Transact-SQL). If the maximum number of seconds is reached and the Snapshot Agent is still waiting, it will exit. A value of 0 means that the agent waits indefinitely, although it can be canceled.
- UsePerArticleContentsView use_per_article_contents_view
This parameter has been deprecated and is supported for backward-compatibility only.
Remarks
Important
If you have installed SQL Server Agent to run under a Local System account rather than under a Domain User account (the default), the service can access only the local computer. If the Snapshot Agent that runs under SQL Server Agent is configured to use Windows Authentication Mode when it logs in to SQL Server, the Snapshot Agent fails. The default setting is SQL Server Authentication.
To start the Snapshot Agent, execute snapshot.exe from the command prompt. For information, see Replication Agent Executables.