index performance tuning in sql server

dropped to 2 times Select * FromUsersWhereUsernameLike 'Ja %'Select * FromUsersWith(Index(Ix_username ))WhereUsernameLike 'Ja %' For more information about include, see the include charm in SQL Server indexes (indexes with contained columns) It is explained that the bookmarked search has a great impact on the query performance and is basically inevitab

Users with(index(IX_UserName)) where UserName like 'ja%' For more information about Include, see the include charm in SQL Server indexes (indexes with contained columns) It is explained that the bookmarked search has a great impact on the query performance and is basically inevitable. This does not mean that the bookmarked search is a great beast. We didn't kn

not necessarily the true inner join:SELECT A.* FROM A INNER JOIN B ON A.KEY=B.KEYMay or may not require party B to be in the execution plan based on what constraints exists. If A.key is an empty foreign key reference B.key, then the optimizer cannot from it must confirm that a B row exists, and each row is scheduled to fall B. If A.key is a mandatory foreign key reference B.key, then the optimizer is free to guarantee the existence of the line from the constraints of the plan to reduce B. Howev

example, the following example uses the pubs database. SELECT au_id, au_lname, au_fname from authors WHERE au_lname = ' White ' The indexes established on the following columns will be useful indexes for the optimizer ? au_lname ? au_lname, au_fname The indexes that are built on the following columns will not work well for the optimizer ? au_address ? au_fname, au_lname Consider using narrow indexes on one or two columns, narrow indexes are more efficient than multiple indexes and composite ind

A Introduced Some "super users" with access to data have learned professional Transact-SQL. The convenience of the Report Builder in SQL Server 2005 Report Services (SSRS) extends to the creation of powerful Transact-SQL queries, making it easier for more users to use it. Their ability to consume system resources is b

the data is consistent, but nothing is perfect. The cost of the Begin Tran is that all the resources locked by the SQL statements cannot be released until the commit is committed before committing.It can be seen that if the BEGIN TRAN too many SQL statements, the performance of the database is poor. Before this large transaction commits, it is bound to block oth

Because SQL Server 2000 lacks some high-end performance, it is considered a 90-pound little. In fact, no strong person can accomplish every feat, and no company needs every high-end feature. For years, many large and small businesses have been using SQL Server to run their c

SQL Server Performance Analysis 　 SQL Server performance analysis Author: tofu chinaasp If you suspect that computer hardware is the main cause of affecting the performance of

: here, both have been positioned to occupy One of the CPUs high in SQL , which can combine the efficiency of business scenarios and SQL , and whether communication with developers such as/DBA is optimized or how to optimize (By the way, it is suggested that the amount of data in the database will have a large impact on the performance gap, this test, 10W of

will query through the indexed range query LODGING_PKBecause the index range query will return a set of values, its efficiency will be the peso cited as the only scan lowerExample 2SELECTfromUserWHERE='mrzhang ';This SQL is executed in two steps, Lodging$manager the index range query (get all rowid that match the condition record), and get the value of the lodging column through the ROWID Access table.Because Lodging$manager is a non-unique index, th

I/O performance diagnostics SQL Server performance is very dependent on the I/O subsystem. Unless your database is fit for physical memory, SQL Server often has database pages in and out of the cache pool. In this way, the actual

executes. Examples are as follows: SET STATISTICS profile on SET STATISTICS IO on SET STATISTICS time on GO – Your SQL script starts SELECT [TestCase] from [Testcaseselect] – Your SQL script is over GO SET STATISTICS Profile OFF SET STATISTICS IO OFF SET STATISTICS Time OFF Alternatively, you can determine how efficient the SQL statement is by adding statements

, however, it is very likely that a page stores five data records. Because a column has one or two more bytes, only four data records can be stored. You may think that there is nothing to save one piece of data, but after the data volume is very large, there will be significant performance differences between 4 pieces of data and 5 pieces of data on one page. The reason for storing more data on a page is not to save storage costs, but the hard disk is

occupied storage space. In actual applications, this extreme situation is rare, however, it is very likely that a page stores five data records. Because a column has one or two more bytes, only four data records can be stored. You may think that there is nothing to save one piece of data, but after the data volume is very large, there will be significant performance differences between 4 pieces of data and 5 pieces of data on one page. The reason for

of addition, subtraction, multiplication, division, the following summary -------------------------------------------- Here is just an extreme example. As a result, a byte deviation is caused to double the occupied storage space. In actual applications, this extreme situation is rare, however, it is very likely that a page stores five data records. Because a column has one or two more bytes, only four data records can be stored. You may think that there is nothing to save one piece of data, but

When installing SQL Server 2003 Development edition and Enterprise Edition on Windows Server 2000, Windows XP, or Windows 2008, the "performance counter registry Configuration unit consistency" check will fail (Windows Server 2008 has not been tested due to no environment cu

The performance damage of bookmarks in SQL Server, sqlserver In my blog, I used to talk about searching for bookmarks in SQL Serverl, and there are many problems they bring about. In today's article, I want to further talk about bookmarking from the perspective of performance