db2 tuning

Linux system tuning authoritative guide, linux tuning Guide 1. Disable SELINUX.1.1 modify the configuration file to make SELINUX disabled permanently effectiveSed's # SELINUX = enforcing # SELINUX = disables # G'/etc/selinux/config ==> restart the system to take effect1.2 temporarily disable SELINUX[Root @ hadoop01 xningge] # setenforceUsage: setenforce [Enforcing | Permissive | 1 | 0]==> The number 0 indic

Need for Performance Tuning In this world of SAP programming, ABAP is the universal language. in most of the projects, the focus is on getting a team of ABAP programmers as soon as possible, handing over the technical specifications to them and asking them to church n out of the ABAP programs within the "given deadlines ". Often due to this pressure of schedules and deliveries, the main focus of making a efficient program takes a back seat.

JVM tuning-calculate the active data size and jvm tuning Active Data Active Data, sometimes called survival data, refers to the size of long-lived objects in the Java heap when the application is in stable running state. In other words, the space occupied by the Java heap after FullGC in the stable running state of the application (memory usage ). 1. Importance of active data computing The calculation of t

JVM tuning-New Generation and jvm tuning New Generation A new generation of Java virtual machines, including eden space and two dedicated vor spaces. The new generation is used to store newly created objects. The new generation features fast object updates and produces a large number of "Dead objects" in a short time ". Garbage collection for young generations is called secondary garbage collection (minor

JVM tuning series: garbage collection and jvm Tuning Summary: jvm is a required series, which summarizes some common jvm collection mechanisms for easy reference. Before optimization, we must understand how it runs. java's Garbage Collection is usually called "GC", which was born in The Lisp Language of MIT in 1960, after more than half a century, it has become very mature. Therefore, this article focuses

Jdk1.6 VM tuning practices (1) and jdk1.6vm tuning practices Linux 2 CPU 16 GB memory, tomcat7 JAVA_OPTS = "-Xmx1024m-Xms1024m-Xss1024K-XX: PermSize = 512 m-XX: MaxPermSize = 1024 m"Cygwin = false Heap memory: Xmx, xms is up to 1/4 of the physical memory size, which saves xms and xmx allocation. Xss, single thread Permsize: permanent partition size, Maxpermsize: up to 1/4 of the physical memory size

JVM tuning summary, jvm Tuning Heap size settingsThe maximum heap size in JVM has three restrictions: the data model (32-BT or 64-bit) of the relevant operating system; the available virtual memory limit of the system; and the available physical memory limit of the system. Generally, 32-bit systems are limited to Gbps ~ 2 GB; 64 indicates that the operating system has unlimited memory. In Windows Server

Chapter 9 JVM tuning recommendations and chapter 9 JVM tuning recommendations Note: This article mainly references distributed Java applications: basics and practices 1. JVM optimization is mainly about memory optimization, mainly in two aspects: Size of each generation Garbage Collector Selection 2. Size of each generation Common Adjustment Parameters -Xmx -Xms -Xmn -XX: Invalid vorra

JVM Tuning Tool Jconsole,jprofile,visualvm JCONSOLE:JDK, the function is simple, but can be used in a certain load of the system. The garbage collection algorithm is tracked in detail. Detailed description Reference here Jprofiler: Commercial software, you need to pay. function is powerful. Detailed description Reference here VISUALVM:JDK, powerful, similar to Jprofiler. Recommended. How to Tune Observe memory release, collection class checking,

:37YesOrchid Island Main 15:34:51Oh.Orchid Island Main 15:35:12Other, not quite understand your data in the situation, not very good fine optimization.Orchid Island Main 15:35:44Should still be quick.Snow Leopard 15:36:34GoodSnow Leopard 15:36:36Let me seeOrchid Island Main 15:37:16For example: The index of the other two tablesSnow Leopard 15:37:31WellOrchid Island Main 15:37:43The full table scan, although the table is small, but to 0.5s, should also be a small proportion.Snow Leopard 15:37:55I

inner table size is multiplied by the number of parallel service processes greater than the physical size.3) Pq_distribute (Tab_name, none,broadcast): This combination forces all data rows within the table to be broadcast to each consuming parallel query service process, while the outer data rows are randomly partitioned. This hint is recommended when the inner table is more than the outside hour. An important principle is that the none/broadcase hint is recommended when the inner table size is

Cache Size| Query_cache_type | On | cache type, determines what queries are cached| Query_cache_wlock_invalidate | OFF | when other clients are writing to the MyISAM table If the query cache is returned , the cache result, or wait for the write operation to complete the reread table to get results+------------------------------+---------+Mysql> show global Status Like "qcache%";+-------------------------+-------+| variable_name | Value |+-----------------------

can avoid Key lookup is perfect, let's revise non-clustered index to include it in the index with the Include keyword His fields are:[SQL] DROP INDEX idx_non_clust_salesorddetaildemo_modifieddate on salesorddetaildemo GO CREATE nonclustered INDEX idx_non_clust_salesorddetaildemo_modifieddate on salesorddetaildemo (ModifiedDate) INCLUDE ( ProductID, UnitPrice ) GO --Clear the cache, only for the development environment! DBCC Freeproccache DBCC dropcleanbuffers GO

Tags: establishing operations common Invalid database index characters NULL join exist Establish an appropriate index (refer to "pose for proper database indexing") Replace or with union (for indexed columns) Replace in, not exist with exist, not Do not declare numbers in character format (invalidates the index, resulting in a full table scan) Do not use SELECT * (List each column after select) Do not perform calculations in join and WHERE clauses (t

ObjectiveIn the previous article we analyzed the role of statistical information in the database, and we have learned how the database uses statistics to control the distribution of the contents of tables in the database. Children's shoes are not clear and can be clicked for reference.As a tuning series of articles, the index of the database is certainly not less, so this article we began to analyze this piece of content, about the basic knowledge of

Tags: upd alt has meaning tab logic for good problem useObjective In the previous article we analyzed the role of statistical information in the database, and we have learned how the database uses statistics to control the distribution of the contents of tables in the database. Children's shoes are not clear and can be clicked for reference. As a tuning series of articles, the index of the database is certainly not less, so this article we began to an

The following articles mainly describe the basic knowledge of DB2 data types. We all know that DB2 has multiple built-in data types, including. Numeric), string character string), graphic string), binary string) or datetime ). There is also a special data type called DATALINK. The DATALINK value contains logical references to files not stored in the database. Numeric DB