Entity Framework Core Plus Batch Delete
Description
Deleting using Entity Framework Core can be very slow if you need to delete hundreds or thousands of entities. Entities are first loaded in the context before being deleted which is very bad for the performance and then, they are deleted one by one which makes the delete operation even worse.
EF+ Batch Delete deletes multiple rows in a single database roundtrip and without loading entities in the context.
// using Z.EntityFramework.Plus; // Don't forget to include this. // DELETE all users inactive for 2 years var date = DateTime.Now.AddYears(-2); ctx.Users.Where(x => x.LastLoginDate < date) .Delete(); // DELETE using a BatchSize var date = DateTime.Now.AddYears(-2); ctx.Users.Where(x => x.LastLoginDate < date) .Delete(x => x.BatchSize = 1000);
Scenarios
Query Criteria
The Delete IQueryable extension methods deletes rows matching the query criteria without loading entities in the context.
// using Z.EntityFramework.Plus; // Don't forget to include this. // DELETE all users ctx.Users.Delete(); // DELETE all users inactive for 2 years var date = DateTime.Now.AddYears(-2); ctx.Users.Where(x => x.LastLoginDate < date) .Delete();
Batch Size
The BatchSize property sets the amount of rows to delete in a single batch.
Default Value = 4000
// using Z.EntityFramework.Plus; // Don't forget to include this. var date = DateTime.Now.AddYears(-2); ctx.Users.Where(x => x.LastLoginDate < date) .Delete(x => x.BatchSize = 1000);
Batch Delay Interval
The BatchDelayInterval property sets the amount of time (in milliseconds) to wait before starting the next delete batch.
Default Value = 0
// using Z.EntityFramework.Plus; // Don't forget to include this. // Pause 2 seconds between every batch var date = DateTime.Now.AddYears(-2); ctx.Users.Where(x => x.LastLoginDate < date) .Delete(x => x.BatchDelayInterval = 2000);
Executing Interceptor
The Executing property intercepts the DbCommand with an action before being executed.
// using Z.EntityFramework.Plus; // Don't forget to include this. string commandText; var date = DateTime.Now.AddYears(-2); ctx.Users.Where(x => x.LastLoginDate < date) .Delete(x => { x.Executing = command => commandText = command.CommandText; });
EF Core InMemory
Specify a DbContext factory in the BatchDeleteManager to enable BatchDelete with In Memory. A DbContext factory must be
// Options var db = new DbContextOptionsBuilder(); db.UseInMemoryDatabase(); // Specify InMemory DbContext Factory BatchDeleteManager.InMemoryDbContextFactory = () => new MyContext(db.Options); // Use the same code as with Relational Database var _context = new MyContext(db.Options); _context.Foos.Delete();
Conclusion
EF+ Batch Delete is the most efficient way to delete records. You drastically improve your application performance by removing the need to retrieve and load entities in your context and by performing a single database roundtrip instead of one for every record.
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