---
title: "BulkSynchronize in EF Core: Mirror Your Data in One Operation - Chris Woody Woodruff"
url: https://daily.dev/posts/bulksynchronize-in-ef-core-mirror-your-data-in-one-operation---chris-woody-woodruff-nhbxuoyw8
source_url: https://woodruff.dev/bulksynchronize-in-ef-core-mirror-your-data-in-one-operation
type: article
source: "We Are .NET"
published: 2026-06-25T14:02:51.020Z
updated: 2026-07-09T02:13:00.183Z
tags: ["c#", "microsoft-sql-server", ".net"]
reading_time: 16
upvotes: 1
comments: 0
language: en
---

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# BulkSynchronize in EF Core: Mirror Your Data in One Operation - Chris Woody Woodruff

**[We Are .NET](https://daily.dev/sources/wearedotnet)** · 16 min read · 1 upvotes · 0 comments

## Summary

EF Core lacks a native method for mirroring a list to a database table. The hand-rolled diff-and-apply pattern (load, classify, insert/update/delete, SaveChanges) works but loads all rows into the change tracker, scales poorly, and is error-prone. Entity Framework Extensions (EFE) provides BulkSynchronize, which stages the source list in a temp table and runs a server-side MERGE to insert new rows, update changed rows, and delete rows absent from the source — all in one transaction without materializing existing rows in .NET memory. The key configuration option is ColumnSynchronizeDeleteKeySubsetExpression, which scopes the delete branch to a specific slice of the table (e.g., by SupplierId or TenantId) to avoid accidentally removing unrelated rows. Benchmarks show BulkSynchronize is 4–5x faster than the hand-rolled approach at 100K rows. The post covers four practical scenarios (API cache sync, reporting table refresh, reference table mirror, per-tenant sync), important production gotchas (change tracker staleness, FK constraints, interceptors not firing), and an honest assessment of when the paid EFE license is justified.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://woodruff.dev/bulksynchronize-in-ef-core-mirror-your-data-in-one-operation>

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---

Tags: [#c#](https://daily.dev/tags/c#), [#microsoft-sql-server](https://daily.dev/tags/microsoft-sql-server), [#.net](https://daily.dev/tags/.net)

[View this post on daily.dev](https://daily.dev/posts/bulksynchronize-in-ef-core-mirror-your-data-in-one-operation---chris-woody-woodruff-nhbxuoyw8)