SQL Server Performance Tuning

I want to add an identity or unique identifier column to a table in order to ensure that each row is unique. For best performance, which one should I use?

One of the key aspects of database table design is to ensure what is called entity integrity. What this means is that you need to ensure that each row in your database tables is unique. If you don’t take the proper precautions, it is possible that one or more rows of your table might be […]

Should I use the old Microsoft JOIN syntax, or the ANSI JOIN syntax for the best JOIN performance?

Question Which of the following joins will produce better performance? ANSI JOIN Syntax SELECT fname, lname, departmentFROM names INNER JOIN departments ON names.employeeid = departments.employeeid Former Microsoft JOIN Syntax SELECT fname, lname, departmentFROM names, departmentsWHERE names.employeeid = departments.employeeid AnswerSQL Server supports two variations of performing JOINs: the ANSI JOIN syntax and the former Microsoft JOIN […]

I don’t like to delete records in our production database, even though we will never need them again. Does this affect performance?

Question I don’t like to delete records in our production database, even though we will never need them again. Because of this, I have included an extra column in every table called the “ACTIVE_FLAG” that is set to one character in length that contains either an “a” for active records or a “d” for deleted […]

In my stored procedures I have the option of calling the same data from either a table or a view. For best performance, should I be calling a table or a view?

Anytime you call data from a view instead of a table, there is additional overhead, which can hurt performance. Because of this, optimum performance can be had by calling your data directly from a table, not a view. If you don’t use the stored procedure often, the performance difference will not be noticeable if you […]

Can the use of NULLS in a database affect performance?

Yes, SQL Server’s performance can be affected by using NULLS in your database. There are several reasons for this. First, NULLS that appear in fixed length columns (CHAR) take up the entire size of the column. So if you have a column that is 25 characters wide, and a NULL is stored in it, then […]

Can you provide some ways that I might be able to avoid using cursors in my applications?

QuestionI understand that I should avoid the use of SQL Server cursors in order to increase an application’s performance. Can you provide some ways that I might be able to avoid using cursors in my applications? AnswerA SQL Server cursor should only be considered in situations where you need to scroll through a set of […]

Is there any performance difference between using SET or SELECT to assign values in Transact-SQL?

This is virtually no difference in performance between using SET or SELECT to assign values. In most cases you will want to use the ANSI standard, which says you should use SELECT. See the SQL Server Books Online for the exact syntax for both options.

I would like some input on the best, most efficient way to store images for use on a website.

QuestionI would like some input on the best, most efficient way to store images for use on a website. The two main options that I see are storing images as a BLOB in SQL Server, or storing the URL of the file in SQL Server, and actually storing the image file on a file share. […]

When creating temp tables within a stored procedure, is it good practice to drop them as soon as they are no longer required?

Maintaining temp tables uses up SQL Server resources, so the sooner you delete them after you are done using them, the better. For most SQL Servers, there is probably not much of a performance difference if you decide to delete them later than sooner, but on a very busy SQL Server that manages lots of […]

Since functions are not pre-compiled, is there any performance gain from using user-defined functions as opposed to stored procedures?

QuestionI work in a SQL Server environment where we have literally hundreds of stored procedures in one database that are utilized for an OLAP application, and likewise for an OLTP application. I have seen in many instances where a stored procedure is used solely because one can pass parameters to it and use these parameters […]