1 性能优化概述

1.1 性能优化简介

This guide provides information on tuning anOracle Database system for performance. Topics discussed in this guide include:

这个小节提供了对一个oracle数据库系统进行性能优化的知识。包括一下几个主题

1.1.1性能规划

Before starting on the instance or SQL tuningsections of this guide, make sure you have read Part II, "Performance Planning".

在学习本小节的实例和sql优化部分之前，请先阅读II部分：性能规划

Based on years of designing and performanceexperience, Oracle has designed a performance methodology. This brief sectionexplains clear and simple activities that can dramatically improve systemperformance. It discusses the following topics:

基于多年的设计和性能方面的经验，oracle已经设计了一套关于性能方面的方法体系。本节描述了能够显著提高系统性能的清晰和简单的方案。该方案涉及到一下主题:

1.1.2实例优化

Part III, "Optimizing Instance Performance" ofthis guide discusses the factors involved in the tuning and optimizing of anOracle database instance.

本节的III部分，“优化实例性能”讨论涉及到oracle数据库实例调优和优化的各种因素。

When considering instance tuning, care mustbe taken in the initial design of the database system to avoid bottlenecks thatcould lead to performance problems. In addition, you need to consider:

当考虑实例优化的时候，数据库系统初始化设计必须要注意防止一些瓶颈，这些瓶颈可能会带来性能方面的问题。此外你需要考虑一下几点：

After the database instance has beeninstalled and configured, you need to monitor the database as it is running tocheck for performance-related problems.

在安装和配置数据库实例之后，你需要监控数据库，因为它时刻运行着来检查跟性能相关的一些问题。

1.1.2.1性能准则

Performance tuning requires a different,although related, method to the initial configuration of a system. Configuringa system involves allocating resources in an ordered manner so that the initialsystem configuration is functional.

对于系统的初始化配置来说 性能调优需要一种与之不同的尽管相关的方法。要以有序的方式分配资源来配置一个系统，这样系统的初始化配置才能起作用。

Tuning is driven by identifying the mostsignificant bottleneck and making the appropriate changes to reduce oreliminate the effect of that bottleneck. Usually, tuning is performedreactively, either while the system is preproduction or after it is live.

通过找到最重要的瓶颈且做一些合适的变更来减少或消除瓶颈的影响来驱动调优的进行。通常来说，调优是需要有反应来验证的，这个系统要么是在试运行中，要么是已经在生产运行了。

1.1.2.2基线

The most effective way to tune is to have anestablished performance baseline that can be used for comparison if aperformance issue arises. Most database administrators (DBAs) know their systemwell and can easily identify peak usage periods. For example, the peak periodscould be between 10.00am and 12.00pm and also between 1.30pm and 3.00pm. Thiscould include a batch window of 12.00am midnight to 6am.