By default Entity Framework updates data one statement at a time. dotConnect for PostgreSQL allows grouping several INSERT/UPDATE/DELETE statements into one SQL block and merging their parameters. Now, instead of sending each DML statement separately, SaveChanges generates and executes statement batches. It increases SaveChanges performance substantially because of reducing number of server calls. This feature is called Batch Updates.
Note that in situations when other applications significantly load the database server, you will get even more performance gain with batch updates, because they reduce the number of database server calls.
Batch Updates are configured with a number of parameters either in code with the PgSqlEntityProviderConfig class or in the project config file as the attributes of the BatchUpdates element of the DmlOptions tag.
AsynchronousBatch - determines whether batches are executed asynchronously (false by default), or a new batch will be created and executed only after the successful execution of the previous batch. It is recommended to enable asynchronous batch execution when the batch size is large. If the batch size is small, the performance gain is compensated by synchronization costs. However, if the batch size is too large, the performance gain will not be significant. To conclude: BatchSize should be large enough to take some time to execute, and small enough not to make the main thread wait for the background thread for too long.
Activating asynchronous batch execution makes sense only if your application will be run on multiple-core processors. On single-core processors asynchronous batch execution provides even less performance than synchronous one.
This property affects only the provider for Entity Framework v1 - v6. It does not affect the Entity Framework Core provider.
For example, this code is used to enable batch updates:
This section describes Batch Updates limitations in Entity Framework v1 - v6. It is not applicable to Entity Framework Core.
TransactionScope cannot be used with batch updates. When using batch updates, concurrency check is not performed. However, you may still enable concurrency check as it is described above.
Some statements cannot be united into batches. When such a statement is encountered, the batch with previously added commands is executed immediately, then this statement is executed separately.
The following statements cannot be united into batches:
It is not recommended to create transactions manually when committing changes. If you create such a transaction (for example, execute context.Database.BeginTransaction() prior to SaveChanges() ), the behavior will be the following:
SaveChanges() will perform the number of database calls (UPDATE/INSERT/DELETE or stored procedure calls) that is multiple of the BatchSize property value. Remainder changes will stay cached, and they will be sent to the database in the following cases:
In Entity Framework Core, you can turn Batch Updates explicitly either per context or globally.
Per context:
Globally, for all DbContext instances: