SQL Server Performance Tuning
I don’t know how to transfer an array to a table, and I even if I can, I don’t know if it will be any faster than using INSERT INTO?
QuestionI have an INSERT INTO SELECT query which appends about 500,000 rows of data to a table. The query takes about 22 minutes to run. I would like it to run in less than 5 minutes, if possible.One solution I thought of was to append the 500,000 rows of data to an array (instead of […]
Question The following two queries produce the same results. Is one or the other versions of these two queries more efficient than the other? SELECT DISTINCT productcode FROM sales SELECT productcode FROM sales GROUP BY productcode Answer The goal of both of the above queries is to produce a list of distinct product codes from […]
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 […]
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 […]
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 […]
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 […]
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.
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. […]