sql server query performance analyzer

Preface Indexes are one of the most important objects in relational databases. They can significantly reduce disk I/O and logical read consumption and improve the query performance of SELECT statements. However, it is a double-edged sword. Improper use affects performance: it requires additional space to store the index information and requires additional overhea

", sqldbtype.structured) {Value = dt}; Cmd. Parameters.Add (param); Cmd. ExecuteNonQuery (); } } Sw. Stop (); Now, we re performing the write operation and found the write efficiency equivalent to SqlBulkCopy. 1.1.3 SummaryThis article through the Blog System User table Design example, describes the mistakes and code flaws that we make in the design process, such as SQL injection, database resource release, and so on, using some co

the CTESELECT *FROM cte_name递归执行的语义如下： 将 CTE 表达式拆分为定位点成员和递归成员。 Run an anchor member to create the first call or datum result set (T0). Run the recursive member, use Ti as the input, and ti+1 as the output. Repeat step 3 until the empty set is returned. Returns the result set. This is the result of the T0 to Tn execution of UNION all. Anchor member is definedThe location of the query is the data setT0, and thenRecursive m

into' Student 'VALUES('8','Lee 48','123','male',' +','Jingan, Shanghai city'); INSERT into' Student 'VALUES('9','Zhang 39','111','male',' +','Shiyan, Hubei province'); INSERT into' Student 'VALUES('Ten','Lee 40','123','male',' +','Jingan, Shanghai city'); I. Querying 5~10 data MySQL Paging query: SELECT * FROM student limit 5, 10; Oracle Paging query: SELECT * FROM (select *,rownum rn from student) wh

, P.last_batch,GETDATE()),0) elapsed_minutes, P.last_batch, P.status, P.program_name, (Select [text] from:: Fn_get_sql (P.sql_handle)) Sql_text fromMaster.. sysprocesses Pwherespid> - andspid @ @SPID and(Status 'Sleeping' and ISNULL(DATEDIFF(MI, P.last_batch,GETDATE()),0)> -)The above script returns statements that run for more than 30 minutes, and it is important to note that:sysprocesses the connection/session/request information in one, where there is no specific time for the start of

Get Server name: Select SERVERPROPERTY (' machinename ') SELECT @ @SERVERNAME Select HOST_NAME () To obtain an IP address, you can use xp_cmdshell to execute the ipconfig command: However, in many cases, because the security issue is not allowed to use xp_cmdshell, you can query sys.dm_exec_connections: SELECT SERVERNAME = CONVERT (NVARCHAR (128), serverproperty (' SERVER

Label:To test SQL performance:One, by setting statistics to view the system situation when executing SQL. Options: Profile, O, time.SET STATISTICS profile on: Displays the time, in milliseconds, that is required to parse, compile, and execute the query.SET STATISTICS IO on: Reports information about the number of scans per table referenced in the statement, the number of logical reads (pages accessed in the

the same, does not necessarily apply to the current query, the performance problem is generated.Why is the execution plan compiled with a completely inconsistent current, and the cache has not been cleaned up so far? There are two reasons for personal speculation, but it is not entirely certain thatOne is based on the current data distribution (statistical information) obtained by an implementation plan, i

, which has the least execution time. However, if the data volume in the database is small, it cannot be compared. In this case, you can view the execution plan, that is, you can obtain multiple SQL statements that implement the same function to the query analyzer, press Ctrl + L to view the indexes used for query, and