db2 performance tuning

let's go back to the experience we just mentioned: "Put the most selective column in front of the index definition", as we discussed, in most cases is right. But there are several exceptions, let's imagine an example, in order to begin, our husband has this most selective index in the definition.Selectzipcode,phone_numberfromcontactwherezipcode= ' 60606 'If you let the two indexes be selected, the DB2 optimizer will most likely choose the index at (z

In addition to the integrated VISUALVM and Jconsole, the JDK itself provides performance tuning monitoring tools such as JPS, Jstack, Jmap, Jhat, and Jstat.In Java development, we sometimes encounter the following problems:OutOfMemoryError, Low memoryMemory leaksThread deadlockLock contention (lock contention)The Java process consumes too much CPU......These problems may be overlooked by many people in thei

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 statement, such as a stored procedure, affects the speed. Now, if the execution of an SQL statement is slow during server code execu

database SELECT statement printed from the log of the program) after the SELECT statement Jmeter testresult No. Type Original Bigger 1 500Connection query/s CPU 100%150q/s 2 Connections 255q/s 160q/s160q/s The problem now is that the Tomcat request 160q/s no more tuning, Tomcat's memory configuration 4G actually used less than 1 G, CPU 8 core utiliza

indicates how many new connection requests are allowed to wait in the queue when all threads are used to process requests. When the queue is full, any new request will be rejected. The default value is 100.The configuration example is as follows: Maxthreads is the maximum number of threads started by Tomcat. The default value is 200. acceptcount is the number of requests queued when the number of threads started by Tomcat reaches the maximum. The default value is 100, the two values work toget

Guide Performance tuning has always been one of the most important work of operations engineers, if you are in a production environment encountered a slow system response, hard disk IO throughput anomalies, data processing speed is lower than expected, or such as CPU, memory, hard disk, network and other system resources have been exhausted for a long time, Then this article will really help you, if no

1 read the Apache configuration optimization recommendations below, then adjust the relevant parameters to observe the status of the server.2 Apache Configuration Tuning Recommendations:3Enter/usr/local/apache2/conf/under the extra directory4 Apache optimization,5 after the above operation, Apache has been able to run properly. However, for sites with a slightly larger number of accesses, the Apache default configuration is not sufficient, we still ne