A Visit to the Doctor Can Resolve Your Slow Query Issues

by Jan 8, 2021

Even the most dedicated DBA is occasionally afflicted with some type of physical ailment that requires a day or two off from work. Sometimes all that is needed is some extra rest and over the counter medicine to help recharge the batteries. At other times, the agenda includes a trip to the doctor for some additional treatment or to obtain more powerful prescription medication. You can’t always solve the issue without expert assistance. 

A similar situation often exists when database professionals are engaged in treating an ailing SQL Server instance. Poorly performing SQL Server databases can frustrate users and drive away prospective customers who are not willing to wait for a slowly responding system to provide results. Problem instances can dominate the time of the teams charged with managing and administering them as they struggle to find the underlying causes and satisfy unhappy users. A few problem SQL Servers can bring down the whole team’s productivity.

Reasons for Performance Degradation

Many factors contribute to SQL Server database performance. It can be hard to pinpoint the reason a particular instance is experiencing performance issues. Here are some of the most common reasons that a SQL Server will begin to misbehave and not meet the expected level of performance.

Poor schema design that is performed without fully understanding requirements often results in badly performing systems. Some of the mistakes that should be avoided at all costs are:

  • Poor table normalization;
  • Redundant data;
  • Foreign keys and constraints;
  • A lack of scheme stress testing.

A bad indexing strategy can have a substantial impact on SQL Server performance. The proper use of indexes, which includes not using too many or too few indexes, is a critical component of a well-performing database. When searching for the culprit in a slowly responding database, indexes should be on the list of potential suspects. 

Incorrect SQL Server deployment can doom your systems from the outset. Many mistakes can be made when configuring your environment that will result in instances that never perform optimally. Some of the most common issues include:

  • Using single TempDB files;
  • Hosting data and log files on the same device;
  • Incorrectly configuring Max Memory;
  • Faulty parallelism settings.

Inefficient SQL code and queries are often at the root of performance problems. This type of problem can be particularly hard to solve in dynamic systems where new code is constantly being introduced. Many common mistakes are made with SQL code including:

  • Excessive use of loops and cursors;
  • Using the SELECT * statement;
  • Datatype mismatches in predicates;
  • Extensive nesting of subqueries.

In some cases, an experienced DBA may be able to determine the reason a database is not performing with just a glance. Usually, it takes a bit more effort and often requires the use of dedicated tools to track down the problems. Using the right tool enables database teams to address the issues and increase SQL Server performance.

Optimizing SQL Servers

SQL Doctor approaches the problem of slow SQL Server performance from several directions. The tool enables a team to check their SQL Servers, diagnose issues that may be impacting them, and find effective solutions that improve database performance. The tool is stocked with an impressive array of features designed to streamline your SQL Servers.

  • Run checkups on specific categories such as index optimization, deadlocks, database configuration, disaster recovery, and many other aspects of SQL Server instances. Health checks can be scheduled or run on-demand when needed. Store health checks for historical comparison and quickly determine the overall health of all registered SQL Servers.

  • Diagnose problems with the information provided by SQL Doctor. Identify issues like blocking sessions, long-running jobs, processor bottlenecks, and insufficient network bandwidth. Check on security settings and verify that no integrity issues exist that would render a database unrecoverable.

  • Tune SQL queries with expert analysis and recommendations for optimization. Check on indexes to identify possible performance impacts and display detailed statistics on query plans. Custom queries can be evaluated without being executed for advanced tuning.

  • Resolve problems using a prioritized list of issues generated by SQL Doctor. Scripts can be automatically created to perform the recommended changes and undo them if necessary. Recommendations from SQL Doctor can be exported to disk so they can be shared with and used by other teams. 

SQL Doctor can fix the issues that plague your on-premises and cloud-based SQL Server instances. It is a tool that provides a database team with the help they need to address complex performance problems. All SQL Servers are eligible for coverage by SQL Doctor, and you should consider adding it to your support software toolbox.