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    How to Analyze SQL Queries for Better Performance

    Analyzing queries is very important for a DBA because when he/she analyzes a query he/she can determine whether the query is performing well or not. There are several things that a DBA needs to understand before analyzing a query. In this blog, I have explained some common mistakes that DBAs make when analyzing SQL queries.

    There are many tools and utilities available in the market for the analysis of SQL queries, but it is always better to analyze a query by yourself and figure out the query which needs to be optimized.

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    In this blog, we will discuss common mistakes that a DBA makes while analyzing a query.

    Missing indexes:

    Indexes are very important in database management systems, but they are also the most neglected part. It is recommended that DBA should create the index for the columns that are used in the WHERE clause. The missing index will lead to bad performance in the application.

    Missing indexes are usually created by inexperienced developers. It is important to have a clear understanding of SQL statements, especially where they are used in applications. When a developer uses SQL statements without knowing their use, they should check whether they are in the right place.

    Sometimes, a query is used in a place where it should not be. If you find this out, you must make the right change. If you fail to do this, your system might become unstable, or it might become a failure. If you don’t have any indexes for a table, you need to create them immediately.

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    For more detail, you can get Oracle DBA Interview Questions and Answers or you can enroll our any of our online Oracle DBA courses.

    Analyzing the wrong table:

    DBA should always analyze the table that is being queried. When you run a query on a specific table, you will get a clear picture of how the query is executing.

    There are several different ways of analyzing a table. One of the most common ways is to use a sample size. For example, you can select a sample size of 10% of the table. If you select this sample size, you will see whether the execution plan is right for the query. If it’s not right, you can then adjust the sample size so that you get a more accurate result.

    The query is not getting optimized:

    First, you have to figure out what causes the slow performance. You have to find out the cause of the query and fix it. It is possible that the query is slow because the database is too large. If that is the case, you should use another database that is smaller. It could also be that the indexing is not done right. If that’s the case, you can optimize the index to see if that fixes the problem. However, this will be a long process, and you may have to go to a database expert. Sometimes, the problem may be the query itself. It is possible that the query you used was designed to be slow, and you don’t know about it. If that’s the case, you should re-write your query to make it more efficient.

    Analyzing the wrong column:

    It is recommended that a DBA should always analyze the column that is being used in the WHERE clause. If you don’t analyze the column that is used in the WHERE clause then you won’t get the desired result.

    Wrong Table join strategy:

    If a query is taking too much time to execute, then you should check whether the join is correct or not. If it is not correct, then you should change the join to make it more efficient.

    A join is a way to combine two tables together. You can join two tables using the equals operator. You must use the equals operator because the join is used to find records that have the same values in two tables. When you use the equals operator, then you will get the matching records from both tables. For example, you can join a table named customers with a table named sales by using the equals operator. The equals operator will show all the sales transactions that were made to customers with a certain email address.

    In short,

    • Step 1: Use the Explain Plan: The first step is to use the Explain Plan. You can do this by right-clicking on the query in question, and choosing “Show Execution Plan”.
    • Step 2: Look for Unnecessary Joins: Now that you have an execution plan, you can use it to find unnecessary joins. For example, if you’re looking at a query with a lot of joins, look at the inner join’s join condition. If the join condition is not necessary, then the join can be removed.
    • Step 3: Look for Nested Loops: If you find a query with many nested loops, it may be better to restructure your data.
    • Step 4: Look for Bad Index Usage: If you’re looking at a query with many bad index usage, try changing the index usage.
    • Step 5: Try Different Indexes: Sometimes, you may need to use different indexes on the same table. Try using the same indexes again, and see what happens.


    In conclusion, to increase your performance, you need to understand the most important factors affecting your database performance. In this post, we’ll discuss the factors that affect the performance of a database. We’ll also show you how to analyze the performance of your queries and improve it.

    When you want to make a strong Oracle DBA career then you should be aware of database services and other database technology. Without having knowledge of Oracle internals, Oracle performance tuning, and skill of Oracle database troubleshooting you can’t be an Oracle DBA expert.

    This expert DBA Team club blog always provides you latest technology news and database news to keep yourself up to date. You should need to be aware of Cloud database technology like DBaaS. All Oracle DBA tips are available in a single unique resource at our orageek. Meanwhile, we are also providing some sql tutorials for Oracle DBA. This is the part of Dbametrix Group and you would enjoy more advanced topics from our partner resource.

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