sql server varchar max 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

,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

is not all on the second server:This shows: Distributed view can effectively solve the system performance problems, the large table different record range---on different servers, and then through the view of the table operation, effective balance server load trafficSplit up access to the boosted data:Placement of data:1. Principles of Data placement:1. Create filegroups on different powerless disks or raid

stress treatment measures, often results will be unsatisfactory. Think like Query OptimizerIn every field there are rules in their domain, and most simply, if you do not conform to the C # specification for programming, such as using keywords incorrectly, then the compilation will be an error. Of course, there will be some hidden rules in each area, and some people will say is the so-called "unspoken rules", such rules are often not materializing, such as you do not meet the best practice to wr

SQL Server CPU performance check and optimization related SQL statements, very good SQL statements, recorded here: -- Begin SQL related to CPU Analysis and Optimization -- use DMV to analyze statements that have used the most CPU

Label:Original: SQL Server performance Tuning (i)--judging system resource bottleneck from waiting stateView the status of all SQL Server tasks at that time (sleeping, runnable, or running) through the DMV2005, 2008 provides the following three view Tudon detailed query:

(3) 1 GB for MPAs, etc. (multi-page apply) (4) 1 ~ 2 GB for the backup program. You can find more information about the Max working thread options http://technet.microsoft.com/en-us/library/ms187024 (v = SQL .105). aspx (For SQL Server 2008 ). Enable Lock Pages in Memory The Windows Group policy determines which W

Life expectancy: PLE, the time that the data page resides in memory. If SQL Server does not have new memory requirements, or has free memory to complete the new memory requirements, then lazy writer will not be penalized and the page will remain in buffer pool, then page life expectancy will be maintained at a relatively high level If page life is always high and low, it indicates that

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

are the collections of data stored on the hard disk. As you can understand, SQL Server has a data page of 8k on the hard disk, with three types of pages: data, LOB, row overflow. For page structure, refer to page and extents: https://technet.microsoft.com/zh-cn/library/ms190969 (v=sql.105). aspx Data (In_row_data): A data row or index row that contains all data

Requirements DescriptionIn a production environment, it is often necessary to collect data to locate a problem or to form a baseline.There are many ways to solve the data acquisition in SQL Server, such as trace, Profile, SQLdiag, extended events and so on.Several scenarios have pros and cons, with the beginning of the SQL Server2012 version, Microsoft's start to

SQL Server Performance Optimization (1) Database Design Can you refer to the recent forum on the emergence of an excellent post http://topic.csdn.net/u/20100415/10/a377d835-acbd-4815-8bcb-b367f88ac8b5.html? 92227Database design includes physical design and logical design:Physical DesignYou can use the raid hardware architecture.To put it simply, the usage policy

Query OptimizerThere are rules in each field. In the simplest way, if you do not conform to the C # specification for programming, such as incorrect keyword usage, an error will be reported during compilation. Of course, there are some hidden rules in each field, and some people may say that they are "hidden rules". These rules are often not clear. For example, if you do not conform to the best practices to write a program, compilation will not report an error, but the

, or has free memory to complete the new memory requirements, then lazy writer will not be penalized and the page will remain in buffer pool, then page life expectancy will be maintained at a relatively high level If page life is always high and low, it indicates that SQL Server has memory pressure. The reference value for ple is: Max

'the value of the Key5' fromheadertable awhereA.headerid= 10000 SELECTA.*, t.a0001 as 'the value of the Key1', t.a0002 as 'the value of the Key2', t.a0003 as 'the value of the Key3', t.a0004 as 'the value of the Key4', t.a0005 as 'the value of the Key5' fromHeadertable AInner Join (SelectHeaderid, Detailkey, detailvalues fromdetailtable) T Pivot (MAX(detailvalues) forDetailkeyinch(a0001,a0002,a0003,a0004,a0005)) T onT.headerid=A.headeridwher

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

performance of the two-range query with YY_BH Index is certainly greatly improved.9. Appropriate and inappropriate in the query conditionsQuery parameters can include actions: =, Inappropriate query parameters are: not,! =, 10. Use Delete sparinglyIn general, some of the logic of deleting data will be implemented more or less in stored procedures. For a small number of tables, the problem is not very big. But for large data tables, deleting data with

worry about it, of course, the above scenario is not completely covered, or at least to explain part. The results we got above look at the execution time, now let's look at the two query execution plans.0 ) from sys.tables as T; 0 ) from sys.tables as T;The above may not be accurate, but also related to hardware configuration, it is possible to coalesce poor performance and IsNull. There should be no big difference in

; (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. (in

types of index performance is not the same, should be used as far as possible first high-performanceThe 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 Username= ' Zhang San ' and age>=21(efficient) Select ... from TableName whe