sql performance tuning steps

%9A%84%E5%93%8D%E5%BA%94%E9%80%9F%E5%BA%A6% e5%88%a9%e5%99%a8/https://my.oschina.net/moooofly/blog/1570635.NETSTAT Network program Communication IP, port, service process number related information (display IP traffic)Https://linux.cn/article-2434-1.htmlCommon commands areNETSTAT-ANTP: Displays information about all TCP connectionsNETSTAT-TNLP: Lists TCP in the listenerNETSTAT-ANLP: List all the listening6.iftop: Network interface traffic monitoring, can be specific to a specific IP address traf

support Create compressed data page19, can dynamically turn off the InnoDB update metadata statistics function: Pollution buffer pool, annlyze table and Show table status will also read the table metadata pollution buffer pool20. Enhanced copy function21. Relay Log Self-repair22, open InnoDB Strict check mode23, dynamically change the system configuration parameters, new parameters can be changed dynamically is a separate table space, InnoDB lock timeout time24. Changes in

same time, tracking different databases and tablesIf you are working with Database Engine Tuning Advisor for SQL, it's better to analyze your SQL statement performance if, and will tell you how to modify it would be better, let's have a look.How Database Engine Tuning Advis

Index | performance ORA FAQ Performance Tuning Series-- The Oracle (tm) Users ' co-operative FAQ Why would a reverse index to useful when the leading column of the "index is" generated from a sequence? When the first column of the index is generated by the sequence, what is the use of a reverse index? --------------------------------------------------------------

filtering out unwanted records before group by. The following two queries return the same result but the second one is significantly faster.The code is as follows:Low efficiency:SELECT JOB, AVG (SAL)From EMP GROUP job has job = ' president ' and AVG (SAL) >xxxEfficient:SELECT JOB, AVG (SAL)From EMPWHERE JOB = ' President 'OR job = ' MANAGER ' GROUP JOB having and AVG (SAL) >xxx7, usually, if the statement can avoid the use of subqueries, as far as possible without sub-query.Because the overhead

threads.Of course, here are a few thread operations can set their own, the maximum recommended for the current system configuration of the logical core number, of course, the large set can be just useless.Second , index Hint hints (index Hint)The so-called index hint hint is to force the query optimizer to perform a scan of a query statement or use a specified index.In this way, we often use in the tuning of a way, many times we create the index is i

This article introduces 10 MySQL Performance tuning methods. each method is very detailed and practical. For more information, see MYSQL, which is the most popular WEB backend database. WEB development languages have developed rapidly recently. PHP, Ruby, Python, and Java have their own characteristics. although NOSQL has been mentioned more recently, I believe most architects will choose MYSQL for data sto

Query performance tuning is a big topic, where the technology involved is very broad, but we can generally divide it into the following levels: 1. Reduce data access. The related technique is to create an appropriate index that converts time-consuming operations such as full table scans, index scans (scan), to index lookups (seek). Establish the correct index, can make the database query

need to focus on and learn in IOS7, and then explore the chapters of their own interest. Plan to inherit the form of notes similar to WWDC2012 and hope that the domestic developers will be helpful.At lastOf course there are some other minor changes, including the addition of the attachment button in the Messageui, Xcode started to support the module, and so on. A complete list of iOS7 new features can be found here (for the time being, you should also need a developer account). The last good ne

Mysql Tomcat C3p0 System Performance Tuning personal summary, System Information The application logic is to use c3p0 to query data in the database and return Json data over http. 1. the initial test result JMeter test result before optimization No. Type Original 1000 data bigger 1 500 Connection 250 query/S 63q/S70q/S 2 1000 connections 255q/S 57q/S65

The latest project used QT 5.5, the project in the process of running a period of time the CPU occupancy rate of 25%, and frequent disconnection of the situation, then decided to optimize the performance of the project.The optimization tool is also VS2010 's own performance analysis tool, the specific method of use see: http://www.cnblogs.com/smark/archive/2011/10/12/2208039.htmlYou can choose "Just My Code

you to optimize the SQL statement for join. Also, the fields that are used for join should be of the same type. For example, if you want to join a DECIMAL field with an INT field, MySQL cannot use its index. For those string types, you also need to have the same character set. (The character set of two tables may be different) "Avoid select *" "always set an ID for each table" We should set an ID for each table in the database as its primary key, a

' Using XML, JSON, or plist Using Nscoding Archive Using a local SQL database similar to SQLite Using Core Data What is the problem with Nsuserdefaults? Although it is very nice and convenient, but it only applies to small data, such as some simple Boolean settings options, and then you need to consider other waysWhat about this structured file of XML? Overall, you need to read the entire file into memory to parse it, which is ve

Tags: mysq tuning target considerations level MySQL performance efficiency transaction1. The leftmost principle notice encounters > 2. Invalid left-most index encountered for like query3.SQL Performance Optimization Goal: at least the range (range lookup to index) level is required to be a ref (normal index) level, pre

· InnoDB Storage Engine 14. Using an Object-relational mapper (relational Mapper) With ORM (Object relational Mapper), you can gain reliable performance gains. All the things an ORM can do, can be written manually. However, this requires a senior expert. The most important thing about ORM is "Lazy Loading", that is to say, only when the need to take the value of the time to really do. But you also need to be careful about the side-effects of this mec

-------------------------------------------------------------------------| Id | Operation | Name | Cost (%CPU) |-------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 4 (0) || 1 | TABLE ACCESS by GLOBAL INDEX rowid| SALES | 4 (0) || 2 | INDEX RANGE SCAN | Index_qu_sold | 3 (0) |-------------------------------------------------------------------------9 Rows selectedSql> alter session Set "_use_nosegment_indexes" =true;Session altered.Sql> CREATE index

order to better match the permission record in the Mysql.user (some are defined by hostname).If the MySQL server has a DNS server set up and the client IP does not have a corresponding hostname on the DNS, then this process is slow and causes the connection to wait.After adding skip-name-resolve, I skipped a process.If the table scan rate exceeds 4000, indicating that too many table scans have been performed, it is likely that the index has not been built, and that increasing the read_buffer_si

and reduced sorting. In the real world, optimized indexes are primarily considered in the following ways: The higher the filter, the more forward the field needs to be. Core SQL Overlay index to ensure maximum efficiency; The sorting field enters the index without interfering with the filter; Multi-SQL comprehensive consideration, re-use index; The third is to find the appropriate proportions by controllin

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, optimization of index items, and other information.In this article we analyze the detection o

WebSphere Performance Tuning dump commandWebSphere - built enterprise applications, often with performance problems and, in severe cases, a memory overflow, is a very annoying thing to do. when the WebSphere application Server (WAS) runs, memory overflows, generating a large number of overflow files, such as Javacore, Heapdump and other files, which takes up a l