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 optimization as described below. If you have any need, please refer to the misunderstanding of
Tags: Benefits Right click Access lib ORM tle blog together SDNReading Query plans:stairway to SQL Server Indexes level 9 by David Durant, 2011/10/05 Original link: http://www.sqlservercentral.com/articles/Stairway+Series/72441/ The Series This article is part of the ladder series: SQL
Label:As a DBA, troubleshooting SQL Server is one of our responsibilities, and a lot of people each month bring us a variety of performance issues that can't be explained but solved. I've heard many times that the performance problems of previous SQL Server are fine and within normal range, but now everything has chang
In the process of paging data using temporary tables, it is found that the query statement conditions are passed through the stored procedure parameters. The parameter conditions cannot be directly used after the SQL where statements are added. There is only one solution to this problem, it is to concatenate SQL statements and conditions into an
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 small as possible, using a Lie Jian index with a small number of bytes (refer to the creatio
It is understood that the vast majority of developers have a thorough understanding of indexing, limited to the fact that most daily work has no chance, and there is no need to care about or understand indexing, when a query is too slow, you can create an index based on the query conditions. When another query is slow, you can create an index, or directly send th
row within the result set partition. The rank of a row is a number of rows before the line involved.
--like here I sort by price, take out the most expensive items in each category from top to bottom
SELECT * from
(
SELECTI.price,i.commodityname,c.classname,rank () Over(Partition byC.classidOrder byI.priceDESC) Rank2 fromCommodityinfo iINNER JOINCommodityclass C onI.commodityclass=C.classid) RWHERERank22; Under SQL
It is understood that most developers have a smattering of understanding of the index, limited to most of the daily work no opportunity, what is not necessary to care about, understand the index, it is really a query too slow to find the query conditions to build an index on OK, which day again a query slow, and then establish an index is, Or simply send the enti
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
First SQL statementSelect CompanyName GSMC,ZB Zhibiao from Left Join T_companycode on T_GSNDZB.GSBH=T_companycode.companyidQuery Result:A second SQL statementSELECT min(CompanyName) GSMC,cast(round(sum(T_xstj.hsje)/10000,2) asNumeric -,2)) Ndje fromT_xstj Left JoinT_companycode onT_companycode.companyid=T_XSTJ.GSBHwhere DateDiff( YearSjgetdate())=0 Group byGsbhQuery Result:Statements that are merged int
Label:Original: 1th week how SQL Server executes a queryHello everyone, Welcome to the 1th week of SQL Server Performance Tuning training . Before we go into the tedious details of SQL Server performance tuning, I want to build th
Usage scenarios:For example, you need to query all student numbers with scores greater than 95, separated by commas into a string, from the Student score table.To prepare the test data:CREATE TABLE score (ID int,score int)INSERT into score values (1,90)INSERT into score values (2,96)INSERT into score values (3,99)It is now necessary to query the result string "2,,3" with a single statement.The
Label: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 doing so. If the cached plan is not found, then command Parser generates a query tree on the T-
Original: SQL Server Tuning Series Advanced (query statement running several indicator value monitoring)ObjectiveIn the previous article, we analyzed how the query optimizer works, including: detailed operation steps of the query optimizer, analysis of filter conditions, opt
SQL random Query
SQL Server:
Select Top N * from Table order by newid ()
The newid () function creates a unique value of the uniqueidentifier type. The preceding statement reads N records randomly from the table.
MySQL: Select * from Table order by rand () limit 10
STR converts a number to a string for compa
Ind_attribute.is_ Disabled as [is disabled] 4 from (5 select Tab_name,index_name, [Co_names]=stuff ((SELECT ', ' +[co_name ') from 6 (select Tab. Name as Tab_name,ind. Name as index_name,col.name as Co_name from sys.indexes IND 7 INNER JOIN Sys.tables tab on Ind. object_id = tab.object_id and Ind.type in (8) inner join sys.index_columns index_columns on tab.object_id = Index_colu mns.object_id and ind.index_id = index_columns.index_id 9 inner join sys.columns Col on tab.object_id = col.object_i
The word booksearch may be unfamiliar to many developers. Many people have encountered this word, but they have not paid enough attention to it, so they have always ignored its existence.
The word booksearch may be unfamiliar to many developers. Many people have encountered this word, but they have not paid enough attention to it, so they have always ignored its existence.
The growth of SQL Server Cognit
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