So, this type of SQL Server replication creates an image of all tables in the publication at once, then it moves the whole image to the subscribers. Snapshot replication does not track the changes made to data like other types of replication, hence, the publisher incurs a little overhead.
Also, if the articles being replicated are large, snapshot replication will require a large bandwidth. The snapshot agent is responsible for creating files with the schema of the publication and the data. The files are temporarily stored in the snapshot folder of the distribution server, and the distribution tasks are recorded in the distribution database. The work of the distribution agent is to move the schema and the data from the distributor to the subscribers. Next, I will be showing you how to configure the Distributor server, the Publisher server, and the Subscriber server for snapshot replication.
The page will show the general guidelines for configuring the distributor. Step 4: In the next window, you will have the option of setting up the current instance as the distributor or choose another instance that has been configured as a distributor.
Step 5: In the next window, choose or type a new path to the SQL replication snapshot folder. Step 6: In the next window, specify the name of the Distribution database and the paths to the local file and the log file. Step A window will appear showing that the configuration of the Distributor was successful. Step 2: A new window will appear giving you the guidelines for creating a Publication.
The snapshot file that contains the schema and the data from published tables, along with database objects is created by the Snapshot Agent and then stored in the snapshot folder for use by the publisher. These files can also be used for the purpose of tracking records in the distribution database. Apart from the working of the snapshot that has been described above, there is also another snapshot process that is divided into two parts and is used when making use of merge publication along with certain parameterized filters.
Investing in a sql fix tool can go a long way in preventing data loss situations. Victor Simon is a data recovery expert in DataNumen, Inc. For more information visit www. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. Snapshot replication distributes data exactly as it appears at a specific moment in time and does not monitor for updates to the data.
When synchronization occurs, the entire snapshot is generated and sent to Subscribers. Snapshot replication can be used by itself, but the snapshot process which creates a copy of all of the objects and data specified by a publication is also commonly used to provide the initial set of data and database objects for transactional and merge publications.
Using snapshot replication by itself is most appropriate when one or more of the following is true:. It is acceptable to have copies of data that are out of date with respect to the Publisher for a period of time. Snapshot replication is most appropriate when data changes are substantial but infrequent. For example, if a sales organization maintains a product price list and the prices are all updated at the same time once or twice each year, replicating the entire snapshot of data after it has changed is recommended.
Given certain types of data, more frequent snapshots may also be appropriate. For example, if a relatively small table is updated at the Publisher during the day, but some latency is acceptable, changes can be delivered nightly as a snapshot.
Snapshot replication has a lower continuous overhead on the Publisher than transactional replication, because incremental changes are not tracked. However, if the dataset set being replicated is very large, it will require substantial resources to generate and apply the snapshot.
Tick the checkbox Create a snapshot immediately and keep the snapshot available to initialize subscriptions. Agent Security. Tick Use the security settings from the Snapshot Agent. Click the Security Settings button to select the account under which the Agent will run. In the opened Snapshot Agent Security window, enter the credentials of the mssql Windows user you have created before. Select connect to the Publisher By impersonating the process account.
Hit OK to save settings and go back to the wizard. After defining the needed user, you can see this user in the Snapshot Agent and Log Reader Agent sections. Tick the upper checkbox to create the publication during the final step of the wizard.
Check your publication configuration and hit Finish to create a new publication. In the Creating Publication window, you can monitor the progress of creating a new publication. Wait for a while and you should see the success status if everything has been done correctly.
If you configure push replication, you should configure the Subscriber to run agents on the main database server MSSQL01 in this case. Select the publication for which to create a new subscription. Distribution Agent Location. For this step, you have to select the replication type by selecting either push subscription or pull subscription.
In our example, we want all agents to run on the source server side, hence, the first option is selected to create push subscription. In our example, the AdventureWorksr was created on the second server by restoring the main source AdventureWorks database from a backup to start replication. Replication is started by replicating only new data but not by copying the entire database after starting the replication process.
Thus, AdventureWorksr is selected as a subscription database in the current example. Distribution Agent Security. Click the button with three dots … and select the user and other security options for the Distribution Agent. Enter the password for the mssql Windows user. Select Connect to the Distributor by impersonating the process account and select Connect to the Subscriber by impersonating the process account options. Hit OK to save settings. Synchronization Schedule. Select the Agent that is located on the Distributor to Run continuously for the current Subscriber.
Initialize Subscriptions. Tick the Initialize checkbox and in the drop-down menu select immediately for when to initialize subscription. You can also select the Memory Optimized option if needed.
Select the upper checkbox to create the subscription s at the end of the wizard. You can check your subscriptions settings and hit Finish to create the subscription. Wait for a while until the subscription is created. If you see the Success status, it means that the subscription was created successfully. There is a Log Reader Agent error in our case. To see error details, select the source database the Publisher in the left pane, select the Agents tab in the right pane and double click the error name.
Cannot execute as the database principal because the principal "dbo" does not exist, this type of principal cannot be impersonated, or you do not have permission.
In the main window, click the New Query button. Right click the publication name and, in the context menu, select View Snapshot Agent Status. In our example, we are going to select all data from the Person. AddressType table. In order to do this, execute the query:. Execute a similar query on the second server to display all data of the Person.
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