---
title: Deprecated Database Engine Features
titleSuffix: SQL Server 2025
description: Find out about deprecated Database Engine features that are still available in SQL Server 2025 (17.x), but shouldn't be used in new applications.
author: MikeRayMSFT
ms.author: mikeray
ms.reviewer: randolphwest
ms.date: 11/18/2025
ms.service: sql
ms.subservice: release-landing
ms.topic: release-notes
ms.custom:
  - ignite-2025
helpviewer_keywords:
  - "deprecated changes 2019 [SQL Server]"
monikerRange: ">=sql-server-ver15 || >=sql-server-linux-ver15"
---
# Deprecated Database Engine features in SQL Server 2025 (17.x)

[!INCLUDE [sqlserver2025](../includes/applies-to-version/sqlserver2025.md)]

[!INCLUDE [sssql25-md](../includes/sssql25-md.md)] deprecates:

- The [Hot add CPU](../relational-databases/thread-and-task-architecture-guide.md#hot-add-cpu) feature.
- The [lightweight pooling](configure-windows/lightweight-pooling-server-configuration-option.md) configuration option and the corresponding **fiber mode** feature.

Features that were deprecated in prior releases are also deprecated in [!INCLUDE [sssql25-md](../includes/sssql25-md.md)]. For information about deprecated features in other versions of [!INCLUDE [ssnoversion-md](../includes/ssnoversion-md.md)], see:

- [Deprecated Database Engine features in SQL Server 2022 (16.x)](deprecated-database-engine-features-in-sql-server-2022.md)
- [Deprecated Database Engine features in SQL Server 2019 (15.x)](deprecated-database-engine-features-in-sql-server-2019.md)
- [Deprecated Database Engine features in SQL Server 2017 (14.x)](deprecated-database-engine-features-in-sql-server-2017.md)
- [Deprecated Database Engine features in SQL Server 2016 (13.x)](deprecated-database-engine-features-in-sql-server-2016.md)

## Deprecation guidelines

When a feature is marked deprecated, it means:

- The feature is in maintenance mode only. No new changes are added, including changes related to addressing interoperability with new features.
- We strive not to remove a deprecated feature from future releases to make upgrades easier. However, under rare situations, we might choose to permanently discontinue (remove) the feature from [!INCLUDE [ssNoVersion](../includes/ssnoversion-md.md)] if it limits future innovations.
- For new development work, don't use deprecated features. For existing applications, plan to modify applications that currently use these features as soon as possible.

You can monitor the use of deprecated features by using the [!INCLUDE [ssNoVersion](../includes/ssnoversion-md.md)] Deprecated Features Object performance counter, or the `deprecation_announcement` and `deprecation_final_support` extended events. For more information, see [Use SQL Server Objects](../relational-databases/performance-monitor/use-sql-server-objects.md).

## Query deprecated features

The values of these counters are also available by executing the following statement:

[!INCLUDE [deprecated-os-performance-counters](../includes/deprecated-os-performance-counters.md)]

## Related content

- [Discontinued Database Engine functionality in SQL Server](discontinued-database-engine-functionality-in-sql-server.md)