steps to optimize sql query

view, SQL Server does a full table scan of table orders and should be inefficient. Take a look at the following query:As you can see from this execution plan, it's not the same as the one above. The lookup of the Orders table in the previous query was using the "Clustered Index Scan" method, and now the "Clustered Index Seek" method was used, and the percentage of the cost of the rightmost two

);}}　　Package Cn.tree.dao;import Java.sql.connection;import Java.sql.drivermanager;import java.sql.resultset;import Java.sql.sqlexception;import Java.sql.statement;import Cn.tree.util.configmanager;public class MenuDao {// Query home directory public void Getmainlist () {Connection Connection = null; Statement st = null; ResultSet rs = null; String Driver = Configmanager.getinstance (). getString ("Jdbc.driver.class"); String URL = configmanager.getin

installation is complete, the finish page provides links to installation summary log files and other important instructions. To complete the SQL Server installation process, click Close. If Setup instructs you to restart your computer, restart it now. When the installation is complete, be sure to read the message from the Setup wizard. Subsequent steps After you upgrade to

Analysis Services (SSAS) commands (that is, xml/a)SQL Server Analysis Services (SSAS) query (MDX)SQL Server Integration Services (SSIS) package (DTS package in SQL Server 2000)Transact-SQL scripts (T-SQL)Let's create a job and th

line 1:ORA-00942: Table or view does not existBecause the query user does not have an EMP object for access, the SQL statement cannot pass the semantic check. 3. Check whether the same statement exists in the shared pool. If the executed SQL statement already has the same copy in the shared pool, the SQL statement wil

mentioned earlier, you can add:IF @status is not NULL @sql + = ' OPTION (OPTIMIZE for (@status = ' C ')) ' If you do not want the optimizer to generate an execution plan by sniffing parameters, you can use:IF @fromdate is not null and @todate are NOT null @sql + = ' OPTION (OPTIMIZE for (@fromdate UNKNOWN, @toda

Original: SQL Server 2012:SQL Server architecture--The life cycle of a query (part 2nd)Planning cache (Plan caches)If SQL Server has found a good way to execute a piece of code, it should be reused as a subsequent request because Generating execution plans is time-consuming and resource-intensive, There is a point in d

)PowershellVarious replication tasksSQL Server Analysis Services (SSAS) commands (that is, xml/a)SQL Server Analysis Services (SSAS) query (MDX)SQL Server Integration Services (SSIS) package (DTS package in SQL Server 2000)Transact-SQL scripts (T-

)PowershellVarious replication tasksSQL Server Analysis Services (SSAS) commands (that is, xml/a)SQL Server Analysis Services (SSAS) query (MDX)SQL Server Integration Services (SSIS) package (DTS package in SQL Server 2000)Transact-SQL scripts (T-

you or any other sysadmin role member can modify the job. If you want a member of a non-sysadmin role to be able to modify the job, then you should change the owner of the job into the corresponding user. Note System Administrator members can change any job, regardless of the job owner. job step A SQL Server Agent job contains at least one step, as described in the first article. When most people say that homework can do some work, it actually me

Use pt-query-digest to find the SQL statement that is not suitable, pt-query-digestsql Overview of pt-query-digest1. Indexes can be executed more quickly, but there must be unreasonable indexes. If you want to find those indexes that are not very suitable and optimize them b

. For example, when multiple indexes are used, the SELECT query may run faster. However, the speed of DML (insert, update, and delete) operations will be significantly slowed down because more indexes must be maintained for each operation. Therefore, if your query mainly contains select statements, it is very helpful to use more indexes. If your applicationProgramTo perform many DML operations, it is necess

Original: SQL query performance analysisOriginal source: http://blog.csdn.net/dba_huangzj/article/details/7623926The performance of SQL query directly affects the value of the whole database, which must be treated solemnly.SQL Server provides a variety of tools, and here's a simple introduction:First, the

words, if the first user chooses to query with the customer number as a parameter, then the optimizer optimizes the customer number, and the underlying processing will have a null form for the customer name, which would cause the table scan if subsequent users search using the customer name, which is certainly not what you expect.In order to avoid this situation, some precautions can be used. One is to split the original SELECT statement in the store

it is to increase I/O.2. Vertical and horizontal partition table, reduce the size of the table (Sp_spaceuse)3. Upgrading hardware4, according to the query criteria, index, optimize the index, optimize access mode, limit the data volume of the result set. Note that the fill factor is appropriate (preferably using the default value of 0). The index should be as sm