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 table row, composed of ColumnModification per column → SharedTableEntryMap is used to track entries mapped to the same row → 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()

Concurrency

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

Shared-Row Value Access

Command state describes the row operation, not every entry: an Added replacement with a Deleted SharedIdentityEntry can participate in a Modified command. Original-value access must use the original value from the deleted shared entry, preserving the previous FK for dependency ordering.

Validation

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