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identify-bottlenecks.md

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title Identify Bottlenecks
description Learn about the causes of bottlenecks, such as insufficient resources and malfunctioning/incorrectly configured resources in SQL Server.
author MikeRayMSFT
ms.author mikeray
ms.date 03/14/2017
ms.service sql
ms.subservice performance
ms.topic concept-article
ms.custom
ignite-2025
helpviewer_keywords
resource bottlenecks [SQL Server]
database monitoring [SQL Server], bottlenecks
performance [SQL Server], bottlenecks
tuning databases [SQL Server], bottlenecks
monitoring server performance [SQL Server], bottlenecks
monitoring performance [SQL Server], bottlenecks
database performance [SQL Server], bottlenecks
server performance [SQL Server], bottlenecks
bottlenecks [SQL Server]
identifying bottlenecks [SQL Server]
monikerRange =azuresqldb-current || >=sql-server-2016 || >=sql-server-linux-2017 || =azuresqldb-mi-current || =fabric-sqldb

Identify Bottlenecks

[!INCLUDE SQL Server Azure SQL Database Azure SQL Managed Instance FabricSQLDB] Simultaneous access to shared resources causes bottlenecks. In general, bottlenecks are present in every software system and are inevitable. However, excessive demands on shared resources cause poor response time and must be identified and tuned.

Causes of bottlenecks include:

  • Insufficient resources, requiring additional or upgraded components.

  • Resources of the same type among which workloads are not distributed evenly; for example, one disk is being monopolized.

  • Malfunctioning resources.

  • Incorrectly configured resources.

Analyzing Bottlenecks

Excessive durations for various events are indicators of bottlenecks that can be tuned.

For example:

  • Some other component may prevent the load from reaching this component thereby increasing the time to complete the load.

  • Client requests may take longer due to network congestion.

Following are five key areas to monitor when tracking server performance to identify bottlenecks.

Possible bottleneck area Effects on the server
Memory usage Insufficient memory allocated or available to Microsoft [!INCLUDEssNoVersion] degrades performance. Data must be read from the disk rather than directly from the data cache. Microsoft Windows operating systems perform excessive paging by swapping data to and from the disk as the pages are needed.
CPU utilization A chronically high CPU utilization rate may indicate that [!INCLUDEtsql] queries need to be tuned or that a CPU upgrade is needed.
Disk input/output (I/O) [!INCLUDEtsql] queries can be tuned to reduce unnecessary I/O; for example, by employing indexes.
User connections Too many users may be accessing the server simultaneously causing performance degradation.
Blocking locks Incorrectly designed applications can cause locks and hamper concurrency, thus causing longer response times and lower transaction throughput rates.

See Also

Monitor CPU Usage
Monitor Disk Usage
Monitor Memory Usage
SQL Server, General Statistics Object
SQL Server, Locks Object