, converting lowercase letters to uppercase and then executing
(20) Use the connector "+" connection string sparingly in Java code!
(21) Avoid using not on indexed columns usually
(22) Avoid using calculations on indexed columns
(23) Replace > with >=
(24) Replace or with union (for indexed columns)
(25) Replace or with in
(26) Avoid using is null and is not NULL on an indexed column
(27) Always use the first column of an index
(28) Replace union with Union-all (if possible)
Performance Tuning for mysql SQL statements
Performance Tuning for mysql SQL statements
In server development, there are sometimes requirements on the concurrency, and sometimes an SQL
Label:Original: SQL Server database Performance tuning tipsThe reasons for the slow query are many, and the following are common: 1. No index or index is not used; 2, I/O throughput is small, forming a bottleneck effect; 3, insufficient memory; 4, the network speed is slow; 5, the amount of data queried is too large; 6, lock or deadlock; 7, the return of unnecess
milliseconds) above and the maximum wait time as a reference. Using the information provided by Sys.sysprocesses to count, about sys.sysprocesses use can refer to "SQL Server performance tuning from user session state analysis". This view listens for blocking information over a period of time. You can set a monitor statement to run every 10 seconds, storing bloc
Tags: disco net text http speed data start time NTS database applicationOriginal: SQL Performance Detection Tool: SQL Server Profiler and Optimization tool: Database Engine Tuning Advisor I. Summary of TOOLS? database application system performance is low, it needs to be opt
indexes are fully utilized during execution. normally, if the index is fully utilized, the name of the execution step will be index seek. note: When analyzing Io, You need to execute the set statistics Io on statement to open the IO analysis.4. Based on the analysis results, add the corresponding indexes and reduce the I/O later.5. for stored procedures, the event viewer should be used to further filter their information. If spid is used (which can be obtained through select @ spid), then the m
poorly run applications outweigh the investment in human, program, and technology using reliable load testing methods. Therefore, I would like to provide the following list of load tests for your application, which will be a magic bullet to prevent your SQL Server performance tuning problem.
Checklist: Load test--sql
.
Experiments have found that different indexes can be created on the master/slave database without interfering with each other (this is related to replication configuration). This makes it possible to create more optimized indexes based on the different usage patterns of the master and from the database. I saw on a foreign blog that using the dynamic view of SQL Server 2005, indexes are automatically created based on the usage patterns of t
SQL Server Performance Tuning 3 Index MaintenancePreface
The previous article introduced how to improve database query performance by creating indexes, which is just the beginning. If you do not need proper maintenance in the future, the indexes you have previously created may even become a drag-and-drop attack and a h
Tags: instance default help input extern data package MSDN One fixOriginal: SQL Server performance Tuning resource waiting network I/OI. OverviewThe main wait for network I/O is async_network_io, when SQL Server returns a data result set to the client, the result set is populated into the output cache (ouput cache), an
Transferred from: http://www.cnblogs.com/MR_ke/archive/2010/08/25/1807856.htmlSQL 2005 Performance TuningSQL Server runs for a period of time, and as data accumulates, SQL runs less efficiently, and in order to use business system normal actions, IT departments often need to spend a high price on SQL tuning experts to
);} /// ///generate time information from the GUID returned by SQL SERVER/// /// comb that contain time information/// Time Public Staticdatetime getdatefromcomb (System.Guid Guid) {datetime basedate=NewDateTime (1900,1,1); byte[] Daysarray =New byte[4]; byte[] Msecsarray =New byte[4]; byte[] Guidarray =GUID. Tobytearray (); //Copy The date parts of the GUID to the respective byte arrays.Array.copy (Guidarray, Guidarray.length-6, Daysarray,2,2);
I. Analysis Phase
In general, there are often too many areas of concern in the system analysis phase, system functionality, availability, reliability, security requirements tend to attract most of our attention, but we must note that performance is a very important non-functional requirements, must be based on the characteristics of the system to determine its real-time requirements, response time requirements , hardware configuration, and so on. It
SQL Server Performance Tuning entry (graphic version)
Step 1: capture sample data during business peaks(About 2 hours ). The tool used is the profiler that comes with sqlserver, also known as the event probe. For example, after entering, click the button on the leftmost side to create a new trail: DBO permission is required for logon, therefore, you can log on wi
There should be different filegroups in the database before the partition table is created;Assuming the database name is Df17datapro, create the user table UserID, put the first 500,000 data in the primary filegroup, place the 50~100 in the FG1 filegroup, and put more than 100 in the FG2 filegroup1. Add File group Fg1,fg2ALTER DATABASE Df17datapro ADD FILEGROUP FG1ALTER DATABASE df17dataproadd FILEGROUP fg22. Adding files to a filegroupALTER TABLEDf17dataproADD FILE(NAME=Df17datapro1,filename=
Recently, the following project encountered an urgent problem, my old horse and young people to fight together. The problem is that many queries are incredibly slow when the pressure data is poured into the database.
Said there must be some basic guidelines for performance issues. The order of performance problems tunning
1 Architecture design (software architecture and database design, poor design is alm
execution plan you can see that the performance improvement is still very large. This is the data of the test environment, if the data volume is large, the advantage is more obvious.So for this problem, the cause is that there is a job data processing frequency is relatively high, in the test environment is difficult to locate where there is a problem, and the speed can also be accepted, but in the production environment is always slower, in fact, th
2014-08-23 BaoxinjianI. Summary
A script that is circulated online to query the efficiency of a single SQL query and export it as an HTML report, similar in function to Dbms_profilerQuery sql_id by session, only run script, export as HTML reportThe SQL script: Http://files.cnblogs.com/eastsea/sqlcheck.zipIi. cases-Using the script data SQL
whenever possible. This section will be a topic at the end of this series. A detailed description of the process is presented here (simplification – Exploration – implementation).Summarize:This paper introduces the process of compiling query, and the concrete content of generating cache, reusing cache, recompiling, etc. There are a number of things to note about optimizing our T-SQL statements, and the more hits we have on the execution plan cache, t
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