name: update-pipeline description: 'Implementation details for EF Core SaveChanges and the update pipeline. Use when changing CommandBatchPreparer, UpdateSqlGenerator, ModificationCommand, or related classes.' user-invokable: false

Update Pipeline

Converts tracked entity changes into database INSERT/UPDATE/DELETE commands during SaveChanges().

Flow

SaveChanges() → DetectChanges() → IDatabase.SaveChanges() → UpdateAdapter creates IUpdateEntry list → CommandBatchPreparer.BatchCommands() → ModificationCommand per entity (maps to table row), composed of ColumnModification (maps to column value) → Topological sort via Multigraph (FK dependency ordering) → Groups into ModificationCommandBatch (respects max batch size) → UpdateSqlGenerator generates SQL per batch → BatchExecutor executes all batches in a transaction → StateManager.AcceptAllChanges()

Other Key Files:

• src/EFCore.Relational/Update/Internal/SharedTableEntryMap.cs — manages entries mapped to the same row

Concurrency

Concurrency tokens → WHERE conditions on UPDATE/DELETE. AffectedCountModificationCommandBatch checks affected rows. Throws DbUpdateConcurrencyException on mismatch.

Validation

• SaveChanges() returns expected affected row count
• Store-generated values propagate back to entities after INSERT/UPDATE
• DbUpdateConcurrencyException thrown when expected for stale data