Table of Contents
- Why Database Performance Monitoring Is Critical
- 6 Key Features of Database Performance Monitoring Tools
- Key Questions to Ask When Comparing Database Performance Monitoring Tools
- Benefits of SQL Server Monitoring
- Key Database Performance Monitoring Metrics
- SQL Server Performance Monitoring Best Practices
Why Database Performance Monitoring Is Critical
Proactively monitoring databases is a key way to ensure high availability and reliable performance. Monitoring tools allow business to track performance metrics both in real time and over time to identify any unexpected fluctuations, bottlenecks, or sustained changes in resource use that may require further investigation.
Monitoring key performance indicators also help pinpoint exactly when a problem started, which makes it easier to zoom in on potential causes and get to the root of the issue. A few of the main areas performance monitoring focuses on include:
- Query details (use the most CPU, run slowly, run frequently)
- Session details (current user connections and locks)
- Scheduled jobs
- Replication details
- Database performance (buffer, cache, connection, lock, and latch)
In addition to troubleshooting performance problems, proactive database monitoring improves ROI and increases the overall health of applications and infrastructure. Monitoring tools that let DBAs analyze historical data from logs and metrics tracking can be used to minimize or prevent database outages, optimize performance, and reduce database operations costs for the organization.
6 Key Features of Database Performance Monitoring Tools
The right performance monitoring tool can make all the difference in how often you have to put out fires and how well you maintain high availability for your users. Here are the top six features to look for in a database monitoring tool:
1. Detailed Data Collection
Getting to the root cause of performance issues is only possible if you know where to look. Details like resource consumption and wait event statistics are key to finding the source of the problem.
2. Current and Historical Data
Having access to both current performance data and details about past performance is the most holistic approach to diagnosing recent database problems and preventing future issues before they occur.
3. Mobile Monitoring
DBAs no longer have to live at the mercy of a failure or system outage and sacrifice work/life balance. Today, mobile performance monitoring applications let you respond to alerts, drill down into the issue, and begin triage anywhere, anytime.
4. Low Overhead
A database monitoring tool that has a significant negative effect on performance is not a great choice. Look for a solution with little to no impact on database workload so you won’t negate the tool’s performance improvement benefits.
5. Alarm Management
High-performing databases are impossible without the help of alarms. Prevent nonstop interruptions and alarm fatigue with a monitoring tool that lets you customize alarms by changing default thresholds and defining priorities so you can isolate critical issues.
6. Cloud Capabilities
The cloud is a game-changer for database performance. Cloud-based monitoring tools are simple to scale in response to changing workload requirements. They also offer unparalleled flexibility because they can be deployed in on-premises, cloud, and hybrid cloud environments.
Key Questions to Ask When Comparing Database Performance Monitoring Tools
There are a lot of database performance monitoring tools on the market, but they are not all created equal. When you are vetting tools to find the one that best fits your organization’s needs, be sure you ask the right questions:
- Is the tool scalable based on changes in workload?
- Are thresholds and alarms customizable?
- Does the tool monitor on-premises, cloud, and cloud hybrid infrastructures?
- Does the tool include dashboards for at-a-glance information and drilldown?
- Is the tool hosted on-premises or in the cloud?
- Will DBAs be able to access the tool anytime, anywhere?
- What kinds of connections can I monitor with this tool?
- Does this tool track historical performance data?
- How long does it take to set up, configure, and deploy the tool?
- Are updates and patching automatic?
Benefits of SQL Server Monitoring
Monitoring SQL Server performance helps you get ahead of issues before they reach the end user. Tracking trends, like resource usage and query speed, makes it easier to spot a problem early, pinpoint the cause, and resolve it quickly. Here are a few more things database performance monitoring solutions enable you to do to improve performance and minimize downtime:
The faster the response, the less likely your users will notice there is a problem. Utilizing a SQL Server monitoring tool with a rapid alert system means you get immediate notifications and that you see the most critical issues first.
Reduce Resolution Time
You can’t resolve an issue until you know what the issue is. SQL Server monitoring helps you locate blocked sessions, gives you ideas for how to unblock them, and identifies the source of the highest-impact issue first, so you can resolve the big problems fast.
Isolate Root Cause
Knowing the root cause of performance issues means you can fix the problem and hopefully keep it from recurring. SQL Server monitoring tools let you analyze workload to find the highest-impact issues and automatically review query plans and database objects to check for missing indexes, inefficient table scans, and missing statistics before offering suggestions for resolving existing problems.
Monitoring SQL Server and tracking metrics over time helps organizations save money on unnecessary investments in additional infrastructure. Performance monitoring identifies issues that can be resolved with tuning and those that require upgrades to existing cloud resources or hardware with no guesswork.
Consistent SQL Server monitoring means there are fewer performance-related tickets to resolve. Fewer tickets frees up DBAs to work on other high-value tasks and overall database quality instead of constantly putting out fires.
Key Database Performance Monitoring Metrics
SQL Server performance problems are often associated with a few common areas: memory, blocked process, resource usage, and indexes. Tracking a few key metrics in each of these areas will speed up your troubleshooting if performance is lagging and help you get to the root cause quickly.
With SQL Server, the buffer cache (or buffer pool) stores copies of recently used data pages. SQL Server always looks in the cache first, but if it doesn’t find what it’s looking for there, it goes to the disk, which significantly slows performance.
Monitoring these metrics will show you when there is a memory problem you need to address.
- Cache Hit Ratio: This metric shows how frequently SQL Server is accessing pages from cache. High values mean that the pages were accessed from memory and not from the disk (this is good). If you are seeing a consistently low cache hit ratio, look for bottlenecks.
- Page Life Expectancy: Page life expectancy is how long a page stays in memory instead of going to disk. You want to see large numbers for page life expectancy, because that indicates your cache hit ratio is good.
- Checkpoint Pages/Sec: SQL Server sets checkpoints to periodically flush modified pages from the buffer to the disk. Be sure to set a baseline for comparison. If you notice an increase in flushed pages, you may have an I/O problem.
Locks and Blocks
SQL Server locks and blocks are caused by multiple clients and processes requesting access to the same resources at the same time. If a resource is already being used, access is locked and the resource is unavailable for subsequent requests. This puts the process on hold until the resource is released and available again.
Blocks normally resolve themselves, but in the cases in which that doesn’t happen, watch these metrics to pinpoint why.
- Lock Waits: This metric should stay around zero. An increase in lock wait indicates there’s a problem with load time, and you will need to track down the root cause of the issue.
- Blocked Processes: Use SQL Server Profiler to capture data about blocked processes. Review the report regularly to identify and resolve blocked processes early, before users notice.
Tracking resource usage metrics lets you quickly identify actual and potential performance issues. Tracking these metrics over time also helps with capacity planning because you know when to expect fluctuations in workload.
- Row Counts: Row counts show you the volume of data associated with a certain table over time. An unexpected increase or decrease indicates a problem and should be investigated.
- Database File I/O: I/O metrics let you track how much data is being written and read by any given data file. Significant and sustained changes could signal a problem, but they may also mean you need to add resources to handle additional throughput. Troubleshoot to confirm.
- Transaction Log Backup Size: SQL Server uses the database log records stored in virtual log files (VLFs) to recover after an overloaded server crashes. Monitoring how many VLFs are in the transaction log is critical, because too many can hamper the recovery and restoration process after an outage.
Indexes speed up operations in database tables that handle a lot of records. Indexes are incredibly useful, but there are inherent issues that can degrade performance if not caught quickly. Keep an eye on these key metrics to catch issues early:
- Fragmentation: Index fragmentation is a byproduct of adding and deleting records. After a period of time, these changes create excessive blank space on too many pages and add new pages out of order. Monitoring index fragmentation lets you know when it’s time to run Rebuild or Reorganize on an index to clean up the fragmentation and improve performance.
- Fill Factor and Page Splits: Fill factor tells your indexes how full each data page should be. If a page is too full, page splits occur; if a page isn’t full enough, you are wasting resources. Monitoring page splits lets you see when a fill factor adjustment is needed.
SQL Server Performance Monitoring Best Practices
Some people love the concept of best practices, and others hate it. But whichever camp you’re in, the reality is that when it comes to SQL Server performance monitoring, there are a few things you can do to make it more effective.
1. Monitor Slow Queries
All queries are not created equal, so keep an eye out for high-impact queries that kill performance. The main culprits include:
- Like expressions with leading wildcards
- Non-indexed columns used in “where” and “group by” clauses
- Like statements that use the “or” operator instead of a union clause
- Wildcard Searches
2. Optimize Schemas
When database schemas are too complex, performance suffers and databases become slow and hard to query. When designing your database schema, try these tips to optimize performance:
- Normalize tables
- Use optimal data types
- Avoid null values
- Don’t use too many columns
- Optimize joins
3. Use Database Logging
Database logs are essential to proactively monitoring database performance. These logs provide information that isn’t always available through performance metrics, like all the queries that are running and how long each one takes to finish. For best results, track system-generated logs as well as:
- Slow query logs
- Scheduled task logs
- Backup logs
- Routine maintenance log
- Any other logs you think may be useful
4. Measure Key Metrics
Tracking key performance metrics is essential to proactively monitoring your databases for problems and then resolving those problems quickly. To ensure you are watching for the most common sources of performance issues, keep a close eye on metrics in these four areas:
- Blocked process
- Resource usage
5. Automate as Much as Possible
Automating database maintenance and optimization takes some of the burden off of the DBA and ensures checks and updates are never overlooked. Performance monitoring tools can save time and effort by automating database monitoring and optimization tasks, including:
- Monitoring disk space
- Inspecting error logs
- Verifying database backups
- Reorganizing database objects