sql performance explained pdf

planOnce we have identified the optimization goals, we need to identify ways to achieve our goals. For SQL statements, there is only one way to achieve the above 2 goals, that is to change the SQL execution plan, let him try to "less detours", as far as possible through a variety of "shortcuts" to find the data we need to achieve "reduce the number of IO" and "reduce CPU computing" targetCommon pitfalls1.c

Original link: http://isky000.com/database/mysql-performance-tuning-sqlNote: This article is based on MySQL, many of which apply to other relational databases at the same time, need some index knowledge as the basis Optimize your Goals Reduce the number of IOIo is always the most vulnerable to the database, which is determined by the responsibility of the database, most of the database operations more than 90% of the time is occupied b

Objective In the previous section we talked about data types and a few things to note in the string, and we went on to talk about string lines as well as other content and interspersed content, short content, in-depth explanation. (Refer to the article "detailed SQL Server data type") Paging Way In SQL 2005 or SQL 2008 we use the Row_number open window functio

, and query 4, the query can only be completed by indexing IX_UserName, without the need to perform a bookmarked search. Now let's take a look at the overhead and query plan of these two queries. We can see that we do not need to prompt the index. The query optimizer has automatically selected our index, logical reads also dropped to 2 times Users UserName Users ((IX_UserName)) UserName For more information about Include, see the include charm in

(IX_UserName)) where UserName like 'ja%' For more information about Include, see the include charm in SQL Server indexes (indexes with contained columns) It is explained that the bookmarked search has a great impact on the query performance and is basically inevitable. This does not mean that the bookmarked search is a great beast. We didn't know what a bookmar

dropped to 2 times Select * FromUsersWhereUsernameLike 'Ja %'Select * FromUsersWith(Index(Ix_username ))WhereUsernameLike 'Ja %' For more information about include, see the include charm in SQL Server indexes (indexes with contained columns) It is explained that the bookmarked search has a great impact on the query performance and is basically inevitab

Users with(index(IX_UserName)) where UserName like 'ja%' For more information about Include, see the include charm in SQL Server indexes (indexes with contained columns) It is explained that the bookmarked search has a great impact on the query performance and is basically inevitable. This does not mean that the bookmarked search is a great beast. We didn't kn

a UV, then every day from the log data out of the corresponding visitor data, the last seven days of guest data stored in a single table, the calculation of weekly UV directly with this table to do the calculation, and do not need to grab a lot of data from the original log data to forget. This is a very simple question and does not even require much knowledge of SQL, but is often overlooked in the development process. This is

I have already explained the principles above. This article mainly provides an example of an application. This instance is taken from gix4 and is complex. Domain Model: The relationships between domain models are as follows: The specific relationship of the model chain on the right has been described in Article 2. This article focuses on the red line: Project: indicates a construction project; Projectpbs: A project contains many PBS;

return, generally speaking, SQL Server itself is not a problem.Two. Other network I/O waitsThere are several other net_waitfor_packet,proxy_network_io,external_script_network_iof here.2.1 Net_waitfor_packet: The explanation in MSDN is that the connection is waiting for network packets to occur during network read. The actual level waits as shown:　　　　　　2.2 Back two proxy_network_io,external_script_network_iof. There is no data in the production enviro

Ten experience in SQL Performance Optimization Abstract: these 10 pieces of experience are the results of the author's own summary and are explained with some code. I hope this article will give some inspiration to database administrators in terms of performance optimization.1. Fuzzy match of the queryAvoid using the l

Label:First, basic unit "page" SQL Server uses a 8KB page to store the data. Physical I/O operations are also performed at the page level. There are many types of pages, specific references (MSDN). We focus more on the structure of the data page, including three parts: the header (96bytes), the data area (data rows and free space), and the row offset array (slots, at least 7bytes): Why the size of the data page is 8k, what are the pros and cons, ther

ObjectiveIn a project, the unity of technology is the most important, the database design is the focus of the emphasis. NoSQL is currently the most popular database, but its practicality and functionality are far less useful than SQL database.Many of the real-world SQL database is criticized for the performance of most of the problem stems from the programmer's u

OverviewWhen we face a problem, we first find the problem and then we solve it. In this article, the main solution is to locate the problem.Workaround1. Learn the various SQL execution frequencies with show statusshow status [like ‘com_%‘];Com_xxx represents the number of times each XXX statement executes.Specific parameters, see:http://lxneng.iteye.com/blog/451985http://www.sandzhang.com/blog/2010/04/07/mysql-show-status-

As a DBA, it is one of our responsibilities to exclude SQL Server issues, and many people each month bring us a variety of performance problems that we cannot explain. I've heard many times that previous SQL Server performance issues were fine and within normal range, but now everything has changed,

simplicity, but it's also a disadvantage in some ways. The MySQL optimizer is efficient, but because of its limited amount of statistical information, the optimizer is more likely to deviate from the work process. For a complex multi-table Join, on the one hand due to its optimizer constraints, and also in the Join this aspect of the effort is not enough, so performance from the Oracle and other relational database predecessors still have a certain d

ObjectiveIn the previous section we explained in detail the calculation column and the calculation column persistence problem, this section we still as explained above to look at the two query performance problem, short content, in-depth understanding, always to review the basics.Persisted computed columns perform better than non-persisted computed columnsWe star

Tags: Sel program solution explained City HTM IPA needsObjectiveThe previous sections are the basic content, this section we talk about the index performance optimization, when the big data processing when the first thought is the index, once encountered such a problem is rushed, all kinds of search data, why not usually solid basic skills, we are simple and simple, short content, in-depth understanding, ra

or output parameters.? B. Process variable naming takes the form of "l+_+ name". C. Variable names are lowercase, and if they are in the form of a phrase, separate each word with an underscore. D. Role? All are named with lowercase characters. Consists of the system name +_+role+_+ noun (or abbreviation) or noun phrase (or abbreviation). E. User? All are named with lowercase characters. Consists of the system name +_+user+_+ noun (or abbreviation) or noun phrase (or abbreviation). III. Basic co