LinqToSql Plus Bulk Update
Description
UPDATE all entities in the database.
All rows that match the entity key are considered as existing and are UPDATED in the database.
// Easy to use context.BulkUpdate(list); // Easy to customize context.BulkUpdate(customers, options => options.ColumnPrimaryKeyExpression = customer => customer.Code);
Purpose
Updating entities using a custom key from file importation is a typical scenario.
Despite the ChangeTracker being outstanding to track what's modified, it lacks in term of scalability and flexibility.
SubmitChanges requires one database round-trip for every entity to update. So if you need to update 10000 entities, then 10000 database round-trips will be performed which is INSANELY slow.
BulkUpdate in counterpart offers great customization and requires the minimum database round-trips possible.
Performance Comparisons
| Operations | 1,000 Entities | 2,000 Entities | 5,000 Entities |
|---|---|---|---|
| SubmitChanges | 1,000 ms | 2,000 ms | 5,000 ms |
| BulkUpdate | 50 ms | 55 ms | 65 ms |
How can I specify more than one option?
You can specify more than one option using anonymous block.
context.BulkUpdate(list, options => {
options.BatchSize = 100);
options.ColumnInputExpression = c => new {c.ID, c.Name, c.Description});
});
How can I specify the Batch Size?
You can specify a custom batch size using the BatchSize option.
Read more: BatchSize
context.BulkUpdate(list, options => options.BatchSize = 100);
How can I specify custom columns to Update?
You can specify custom columns using the ColumnInputExpression option.
Read more: ColumnInputExpression
context.BulkUpdate(list, options => options.ColumnInputExpression = c => new {c.Name, c.Description});
How can I specify custom keys to use?
You can specify custom key using the ColumnPrimaryKeyExpression option.
Read more: ColumnPrimaryKeyExpression
// Single Key context.BulkUpdate(customers, options => options.ColumnPrimaryKeyExpression = customer => customer.Code); // Surrogate Key context.BulkUpdate(customers, options => options.ColumnPrimaryKeyExpression = customer => new { customer.Code1, customer.Code2 });
Why BulkUpdate doesn't use the ChangeTracker?
To provide the best performance possible!
Since using the ChangeTracker can greatly reduce performance, we chose to let SubmitChanges method handle scenarios with ChangeTracker and BulkUpdate, scenarios without it.
Why BulkUpdate is faster than SubmitChanges?
The major difference between both methods is SubmitChanges uses the ChangeTracker but not the BulkUpdate method.
By skipping the ChangeTracker, some methods like DetectChanges are no longer required which greatly helps to improve the performance.