SQL Server Performance Tuning
How do I find the most frequently occurring value for all data in a table? How do I find that value per group?
As always, there is more than one way to get a correct result. But which way gives you the best performance? Let’s first build a simplified test scenario to illustrate what we’re after. CREATE TABLE #t (ArticleGroup CHAR(2), Price DECIMAL(8,2)) INSERT INTO #t VALUES(‘SP’, 1.2) INSERT INTO #t VALUES(‘SP’, 1.2) INSERT INTO #t VALUES(‘SP’, 2.1) […]
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. […]
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 […]
Question I have a table with over 40 million rows. I would like to partition the table base on the creation date. Does SQL Server support table partitioning? AnswerEven with the fastest hardware and optimally-written queries, there comes a point in the size of a table where there are just too many rows to handle quickly. […]
QuestionI have a “main” table named Property. This table has approximately 60 columns and over 1 million records (this record count will increase significantly over time). Of these 60 columns, approximately 25 are IDs which reference values in multiple different lookup tables. In any given view, query or store procedure, I end up joining 12-25 […]
Generally speaking, if the data you are dealing with is not large, then the table datatype will often be faster than using a temp table. But if the amount of data is large, then a temp table most likely will be faster. Which method is faster is dependent on the amount of RAM in your […]