sql server sparse columns performance

after you've processed historical data and report data, then add these new hardware, such as faster CPUs and hard drives, larger memory, and so on, but add new hardware postscript to modify your SQL Server configuration to accommodate these new hardware, such as opening/ 3G switch to use more memory. Scale out when scaling the up does isn't suffice or is cost-prohibitive. Use horizontal expansion When yo

We can use set statistics Io and set statistics time to analyze the performance of T-SQL statements. The method is as follows: In the SQL Server Query analyzer, run: Set statistics profile onset statistics Io onset statistics time ongo -- // The SQL statement to

) include (Gender,createtime) You can see that we have modified the index after using include Gender,createtime, the index Ix_username has reached the full coverage of all the columns of the datasheet users, at which point there is no doubt that Query 2, query 3 does not appear bookmark lookup, The bookmark lookup for query 4 also disappears. At this point the index ix_username structure is as follows Index Ix_username has reached the

,t.text from sys.dm_exec_query_stats as s -information about statements cross apply Sys.dm_ Exec_sql_text (S.sql_handle) as T ORDER by avgtotal Desc --Evaluation of database IO select * from Sys.dm_io_pending_io_requests --Request view of suspend IO select * from Sys.dm_io_ Virtual_file_stats ((Select db_id (' AdventureWorks2014 '), null) --function returns I/O statistics for data and log files- -The description file is suspended Select S.file_id,r.io_pending from sys.dm_io_pend

clustered index, and the fields frequently used in the WHERE field are used as the fields of the clustered index. Avoid creating clustered indexes on varchar columns. We will compare the performance of 10 million pieces of data at a time (for the SQL statement generated for the test data, seeAppendix): SELECT OrderDate, Amount, Refno FROM ordDemo WHERE Refno

frequently (by the way, it becomes a clustered index), and can better meet most of our needs. The auto-increment ID column is omnipotent. The Int type only occupies 4 bytes to fully meet the requirements of narrow indexes. The absolute sequential storage can effectively reduce index fragmentation, which fully conforms to our table habits, it is always correct to use an auto-increment ID column as the primary key. Here, the key columns of clustered

, because the amount of data is small, designers and testers often only notice the implementation of the function, and rarely notice the lack of performance, until the system put into actual operation for some time, only to find that the performance of the system is decreasing, At this time to consider the improvement of system performance will cost more human an

disperse the concurrency pressure of the large scale data, also can speed up the speed of special query, the redundant field can reduce the connection of database table effectively and improve the efficiency.3.Design of the primary keyThe primary key is necessary, and the primary key for SQL Server is a unique index, and in practice, we tend to choose the smallest key group to work as the primary key, so t

Many of my friends may be making mistakes in performance optimization as described below. If you have any need, please refer to the mistakes in SQL Server query performance optimization to get out of the index. Many of my friends may be making mistakes in performance optimiz

; (efficient) Select ... from [dept] where [sal]>25000/12; 10, different types of index performance is not the same, should be used as far as possible first high-performance The index lookup efficiency of a numeric type is higher than the string type, and the index of fixed-length string char, nchar is higher than the variable-length string varchar, nvarchar. (inefficient) Select ... from tableName where Us

are in order.Then, when SQL Server is doing all of these things, it creates locks to ensure that users get meaningful results. SQL Server guarantees that when each statement is executed, the database is fully predictable (for example, predicting how SQL executes) and managi

Label:Original: SQL Server 2008 Performance Troubleshooting (i)--IntroductionRemark: I spent a lot of work time translation, no plagiarism, allow reprint, but please indicate the source. Because of the length, not a post all finished, but also not so fast all translated, so according to the chapter published. Due to my limited level, translation results must be p

data, the same query in different circumstances may produce the opposite result, how to apply well is mainly in our personal understanding and understanding, hope to see this article friends can deepen some understanding of the index and understanding , and get rid of the error of index and develop high performance application. I am not a DBA, just a common developer, the above are some of the actual work experience, experience, in view of my level i

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

Myth 1. An index is established on a table and an indexed column is used at query time, and the index is bound to take effectFirst of all, it is wrong to make it clear that the SQL Server query optimizer is a cost-based optimizer that determines whether to use an index, what type of index to use, and which index to use, through a series of complex judgments. SQL