What are the differences between Oracle and SQL Server?

1. Platform: Oracle is cross-platform, while SQL Server is mostly Windows-based.

2. Licensing: Oracle's licensing is more complex and expensive.

3. Storage: Oracle uses tablespaces; SQL Server uses filegroups.

4. Syntax: Differences in SQL syntax and features.

5. Scalability: Oracle is known for better scalability in large envi

ronments.

Oracle and SQL Server are both powerful relational database management systems (RDBMS), but they differ in several aspects, including architecture, language, licensing, and platform compatibility. Here’s a breakdown of the key differences:

1. Architecture & Storage
Oracle: Uses a multi-version read consistency (MVRC) model, ensuring that queries see a consistent snapshot of data.
SQL Server: Uses a different locking mechanism that can lead to more blocking in high-concurrency environments.
2. Database Structure
Oracle: Uses a multi-tenant architecture with CDB (Container Database) and PDB (Pluggable Databases), allowing multiple databases to run under a single instance.
SQL Server: Uses a single-instance architecture where each database operates independently.
3. Transaction Control & Concurrency
Oracle: Implements UNDO tablespaces to manage transactions and automatically rolls back uncommitted transactions upon failure.
SQL Server: Uses tempdb and transaction logs, but can sometimes result in blocking due to its lock-based concurrency control.
4. Language & Query Syntax
Oracle: Uses PL/SQL (Procedural Language for SQL) for procedural logic.
SQL Server: Uses T-SQL (Transact-SQL), which has slight syntactical differences from PL/SQL.
5. Backup & Recovery
Oracle: Provides RMAN (Recovery Manager) for full and incremental backups, including block-level recovery.
SQL Server: Uses SQL Server Management Studio (SSMS) Backup & Restore and transaction logs for recovery.
6. Licensing & Cost
Oracle: Typically more expensive, offering licensing per CPU core.
SQL Server: Licensing is generally more flexible, with an option for per-core or per-user licensing.
7. Platform Support
Oracle: Runs on Windows, Linux, and UNIX.
SQL Server: Originally Windows-only but now supports Linux (since SQL Server 2017).
8. High Availability (HA) & Scalability
Oracle: Uses RAC (Real Application Clusters), Data Guard, and Active Data Guard for high availability.
SQL Server: Uses Always On Availability Groups and Failover Clustering.
9. Cloud Integration
Oracle: Strong cloud presence with Oracle Cloud Infrastructure (OCI) and supports AWS/Azure integration.
SQL Server: Integrated deeply with Microsoft Azure SQL Database and Managed Instances.
10. Security & User Management
Oracle: Uses roles and profiles along with Virtual Private Database (VPD) and Transparent Data Encryption (TDE).
SQL Server: Provides row-level security (RLS) and Always Encrypted features.