Entity Framework Bulk Update
Definition
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.
SaveChanges 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 |
|---|---|---|---|
| SaveChanges | 1,000 ms | 2,000 ms | 5,000 ms |
| BulkUpdate | 50 ms | 55 ms | 65 ms |
