sql query optimization techniques

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

high-performance applications. I am not a DBA, but an ordinary developer. The above are some experiences and experiences in my practical work. In view of my very limited level, if you say something wrong or cannot understand it, I hope you can correct it to avoid misleading others. I am very grateful. In the future, I will continue to write some practical experience on SQL Server query performance

Label: SQL Server Query optimization method The reasons for the slow query are many, the following are common 1, no index or no index (this is the most common problem of slow query, is the defect of program design)2, I/O throughput is small, forming a bottleneck effect3. No

than the number of rows of data The statements and data used in the example are used only as demos, the actual development application is more complex than the sample 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 in

= NULL; SET @Name = ' Ja '; SELECT * from studentwhere (@ID = 1 OR stuid = @ID) and (@Sex are null or stusex = @Sex) and (@Name is null or stuname like '% ' + @Name + '% ')Here declare three variables, as passed parameters, passed parameters have a default value, or NULL, we add in where to use or add judgment, first Judge @ID =-1, if the condition is established, or will not judge the condition after or, to here (@ID = 1 OR stuid = @ID) Returns a true, equivalent to where true and ..., so it i

Http://www.cnblogs.com/dubing/archive/2011/12/09/2278090.htmlRecently the company has come to a very tiger DBA 10几 years of experience here is called Cai Teacher. Let us share the precious wealth that Cai Lao has brought to us, with the consent of our Chua. Welcome other DBAs to shoot bricks Directory1. What is the execution plan? The execution plan is dependent on what information.2, unified SQL statement to reduce parsing overhead3. Reduce the

Directory1. What is the execution plan? The execution plan is dependent on what information.2, unified SQL statement to reduce parsing overhead3. Reduce the nesting of SQL statements4. Staging intermediate results using temporary table5. The OLTP system SQL statement must take a binding variable6. The spy problem of the bound variable of the tilted field7. Begin

name to run on any member server. The system operates as if each member server has a copy of the original table, but there is only one member table and one distributed partitioned view on each server. The location of the data is transparent to the application.11. Rebuild the index DBCC REINDEX, DBCC INDEXDEFRAG, shrink data and log DBCC SHRINKDB,DBCC shrinkfile. Sets the auto-shrink log. For large databases do not set the database autogrow, it will degrade the performance of the server. There's

Tag: Style color IO using strong SP data on problemIn recent times, has been exploring the SQL Server query performance issues, of course, also aimless search for a lot of information, but also from the online great God's articles learned a lot, here, to the great God salute. It is by the great God selfless dedication of the influence of the spirit, so, the younger brother also in return, share about the se

ArticleDirectory Create highly selective Indexes Create multi-column Indexes Avoid creating indexes for small tables Use indexes with filter clauses Create an index for the order-by/group-by/distinct column to shorten the response time Use Outer Join for restrictions Optimize Indexes Creating useful indexes is one of the most important ways to improve query performance. Useful indexes can help reduce the disk I/O

I. Operator Optimization 1. In Operator SQL statements written in are easy to write and understand, which is suitable for modern software development. However, SQL statements using in always have low performance. The following differences exist between SQL statements using in and

In database principles, clustering indexes are interpreted as follows: the order of clustering indexes is the physical storage order of data, while the non-clustering indexes are interpreted as follows: the index order is irrelevant to the physical data arrangement order. Because of this, a table can have at most one clustered index. However, this definition is too abstract. In SQL Server, indexes are described through the binary tree data structure.

In database principles, clustering indexes are interpreted as follows: the order of clustering indexes is the physical storage order of data, while the non-clustering indexes are interpreted as follows: the index order is irrelevant to the physical data arrangement order. Because of this, a table can have at most one clustered index. However, this definition is too abstract. In SQL Server, indexes are described through the binary tree data structure

Query optimization on SQL statements. The foreground application works on the database server, and ultimately relies on the SQL statements in the application. According to incomplete statistics, SQL statements consume about 80% of the database server's resources. Therefore,

SQL query optimization many people do not know how SQL statements are executed in SQL Server. They are worried that SQL statements they write will be misunderstood by SQL Server. For ex

SQL Server query performance optimization-index and SARG (I) For non-SARG statements, SQL SERVER must evaluate each record to determine whether it meets the WHERE clause conditions. Therefore, indexes are usually useless for queries using non-SARG conditions. A non-SARG statement usually contains the following operatio

compilation, only 0.7 seconds to get the results. So how do you precompile, or use an existing execution plan?SQL Server has an optimization algorithm that holds the execution plan for the previous execution of the SQL statement, and all execution plans are stored in the Sys.syscacheobjects table, and if the current SQL