Ledger Tables for Immutable Data in SQL Server 2022

Ledger Tables for Immutable Data in SQL Server

SQL Server Ledger Tables provide tamper-evident and immutable data storage, ensuring that historical changes remain unaltered. This feature, introduced in SQL Server 2022, enhances security and compliance by maintaining cryptographic proof of data integrity.

1. What Are Ledger Tables?

Ledger tables are a special type of table that automatically records every insert, update, and delete operation in a historical ledger table. This ensures that data cannot be modified or deleted without detection.

? Key Features:

• Immutable Audit Trail: Prevents unauthorized modifications.
• Cryptographic Proof: Uses blockchain-like hashing for verification.
• System-Managed Ledger Tables: Automatically maintain historical records.
• User-Managed Ledger Tables: Allow controlled logging with additional flexibility.

2. Types of Ledger Tables in SQL Server

?? System-Versioned Ledger Table

• SQL Server automatically tracks changes in a history table.
• Provides tamper-proof auditing without extra coding.

?? Updatable Ledger Table

• Allows updates but maintains an append-only history.
• Uses a ledger view to track all changes.

3. How to Create a Ledger Table

Step 1: Enable Database Ledger

ALTER DATABASE MyDatabase SET LEDGER=ON;

Step 2: Create a Ledger Table

CREATE TABLE Customers_Ledger (

??? CustomerID INT PRIMARY KEY,

??? Name NVARCHAR(100),

??? Email NVARCHAR(100)

) WITH (LEDGER = ON);

Step 3: Verify the Ledger

SELECT * FROM sys.database_ledger_transactions;

4. Benefits of Ledger Tables

? Compliance & Security: Ensures regulatory compliance (e.g., GDPR, HIPAA).

? Tamper-Evident: Cryptographic hashes protect against unauthorized changes.

? No Performance Overhead: Optimized for minimal impact on query performance.

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