Correlating Worst-Performing Queries with Missing Indexes

Linking Poorly Performing Queries to Absent Indexes


3 min read


In the world of database performance optimization, identifying and resolving performance bottlenecks is crucial. One common cause of slow query execution is the absence of proper indexes. In this blog post, we will explore the relationship between worst-performing queries and missing indexes, and discuss how correlating these two factors can significantly improve database performance.

The Impact of Missing Indexes on Query Performance

Indexes play a vital role in enhancing query performance by allowing the database engine to quickly locate and retrieve the required data. When an index is missing for a particular query, the database has to perform a full table scan, scanning every row to find the desired data. This lack of efficient data retrieval can lead to significant performance degradation, resulting in slower query execution times.

Identifying Worst-Performing Queries

To improve database performance, it is essential to identify the queries that are causing the most significant performance issues. These queries, commonly referred to as worst-performing queries, are often the ones that consume excessive CPU resources or take longer to execute. By analyzing query execution plans, database administrators can pinpoint the queries that need optimization.

Correlating Worst-Performing Queries with Missing Indexes

Once the worst-performing queries have been identified, it is crucial to determine if their poor performance is associated with missing indexes. Database management systems provide tools and utilities to analyze query execution plans and recommend potential missing indexes. By examining the execution plans and suggested indexes, database administrators can correlate the queries with missing indexes and take appropriate actions.

Correlating worst-performing queries with missing indexes can lead to significant performance improvements. By creating the recommended indexes, the database engine can efficiently locate and retrieve the required data, resulting in faster query execution times. It is important to note that not all missing indexes are relevant for performance optimization, and database administrators should carefully evaluate the suggested indexes before implementing them.

The Process of Correlation

To correlate worst-performing queries with missing indexes, database administrators can follow a systematic process. First, they need to identify the queries that are causing performance issues by analyzing query execution plans and monitoring system resources. Once the queries are identified, administrators can gather information about the tables and columns involved in the queries. They can then use database management system tools to analyze the execution plans of these queries and identify potential missing indexes.

Analyzing the execution plans provides insights into the query execution process and helps identify areas where indexes can improve performance. The execution plans highlight the operations performed by the database engine, such as table scans, joins, and sorting. By examining these operations, administrators can determine if the absence of an index is causing inefficiencies in query execution.

After identifying potential missing indexes, administrators can evaluate their impact on performance. They can consider factors such as the frequency of the query, the number of rows in the table, and the selectivity of the columns involved. This evaluation helps prioritize the creation of indexes based on their potential impact on query performance.

Once the evaluation is complete, administrators can create the missing indexes and monitor the impact on query execution times. They should also consider any potential drawbacks of creating additional indexes, such as increased storage requirements and potential overhead during data modification operations.


Improving database performance relies on identifying and resolving performance bottlenecks. Correlating worst-performing queries with missing indexes is a crucial step towards optimizing query execution times. By analyzing query execution plans and identifying missing indexes, database administrators can take targeted actions to enhance database performance. Remember, a well-optimized database leads to improved application performance and overall user satisfaction.