Oracle is a powerful database management system that can not only store and manage large amounts of data, but also efficiently query and process data. Oracle's SGA (System Global Area) is an important area in the memory of the database. It stores various information required for the operation of the Oracle database, including data dictionary information, buffers, log buffers, etc. This article will discuss how to modify Oracle's SGA to improve database performance and stability.
- Understanding Oracle's SGA
Before modifying Oracle's SGA, we first need to understand the structure and function of SGA. SGA is an important part of Oracle database memory. It undertakes very important tasks when the database is running. SGA is mainly divided into the following parts:
(1) Shared Pool: The shared pool occupies an important position in SGA. It stores Oracle's shared SQL and PL/SQL statements, shared Shared components such as cursors.
(2) Data Dictionary Cache: The data dictionary is a very important component in the Oracle database. It stores various objects of the database, including tables, indexes, triggers, etc. The data dictionary cache stores all data in the data dictionary.
(3) Buffer Cache: The buffer is a very core component in Oracle. It stores all data blocks in Oracle. The buffer cache stores the most commonly used data blocks on disk.
(4) Redo Log Buffer: The redo log cache stores information about database operations, including inserts, updates, deletes, etc.
(5) Fixed Area: The fixed area stores some data structures within the Oracle database.
- How to modify SGA
After understanding Oracle's SGA structure, we can start to modify SGA. There are many ways to modify SGA. Below we introduce several common methods.
(1) Modify SGA by modifying the parameter file
The most common way to modify Oracle's SGA is by modifying Oracle's parameter file (init.ora or spfile). The following parameters can be modified:
SGA_TARGET: This is a new parameter after Oracle 10g. In 10g and later versions, a fixed SGA size can be set. By setting SGA_TARGET, the Oracle system will automatically allocate the size of each part of the SGA. For example, if you need to set SGA_TARGET to 3GB, the Oracle system will automatically allocate the size of the shared pool, data dictionary cache, buffer cache, and redo log cache to meet the size limit of SGA_TARGET.
SGA_MAX_SIZE: This parameter defines the maximum value of SGA. If you need to increase the size of SGA, you can do so by modifying the SGA_MAX_SIZE parameter.
PGA_AGGREGATE_TARGET: This parameter defines the size of the PGA, which is the memory size used by Oracle to process data. If you need to increase the size of the PGA, you can do so by modifying the PGA_AGGREGATE_TARGET parameter.
For example, if you need to set SGA_TARGET to 3GB, SGA_MAX_SIZE to 3.5GB, and PGA_AGGREGATE_TARGET to 500MB, you can add the following configuration information to the initialization parameter file:
SGA_TARGET=3G
SGA_MAX_SIZE=3.5G
PGA_AGGREGATE_TARGET=500M
(2) Dynamically modify SGA
If you need to modify SGA without restarting the Oracle instance, you can use dynamic SGA parameters set up.
You can modify the following parameters:
SGA_TARGET: You can dynamically modify the SGA_TARGET parameters through ALTER SYSTEM SET SGA_TARGET=XXX.
SAG_MAX_SIZE: The SGA_MAX_SIZE parameter can be dynamically modified through ALTER SYSTEM SET SGA_MAX_SIZE=XXX.
PGA_AGGREGATE_TARGET: The PGA_AGGREGATE_TARGET parameter can be dynamically modified through ALTER SYSTEM SET PGA_AGGREGATE_TARGET=XXX.
For example, if you need to set SGA_TARGET to 2GB without restarting the Oracle instance, you can use the following statement:
ALTER SYSTEM SET SGA_TARGET=2G
(3 ) Modify using SGA management tools
Oracle also provides some SGA management tools, such as Oracle Enterprise Manager and Database Configuration Assistant, which can be used to modify SGA. These tools can manage SGA through a graphical interface, making SGA modification more intuitive and convenient.
- Notes
Before modifying SGA, you need to pay attention to the following issues:
(1) Modify SGA with caution
You need to be very careful when modifying SGA, because improper modification may cause the database to crash. Before modifying, it is recommended to back up the data and parameter files so that the database can be quickly restored when problems occur.
(2) The size of the SGA needs to be determined based on the actual situation
The size of the SGA needs to be determined based on the actual situation. If the SGA is too small, it may cause database performance to decrease; if the SGA is too large, it may cause an OOM (Out of Memory) error in the operating system, or even cause the database to crash.
(3) The size of SGA needs to be dynamically adjusted
The size of Oracle's SGA needs to be dynamically adjusted. For different applications and loads, the size of the SGA needs to be adjusted dynamically. It is recommended to regularly monitor the performance indicators of the database, such as Buffer Cache hit rate, PGA usage, etc., so that SGA problems can be discovered and adjusted in a timely manner.
- Summary
The SGA of Oracle database is an important part of the database memory, which stores various information required for database operation. When modifying SGA, it needs to be adjusted according to the actual situation and load. It is recommended to treat SGA modifications with caution to avoid database crashes caused by improper modifications. At the same time, it is recommended to regularly monitor the performance indicators of the database in order to promptly detect SGA problems and make adjustments to ensure the stability and efficiency of the database.
The above is the detailed content of Let's talk about how to modify Oracle's SGA. For more information, please follow other related articles on the PHP Chinese website!

This article explains PL/SQL cursors for row-by-row data processing. It details cursor declaration, opening, fetching, and closing, comparing implicit, explicit, and ref cursors. Techniques for efficient large dataset handling and using FOR loops

This article examines Oracle database segment types (data, index, rollback, temporary), their performance implications, and management. It emphasizes choosing appropriate segment types based on workload and data characteristics for optimal efficienc

This article explores Oracle database performance testing tools. It discusses selecting the right tool based on budget, complexity, and features like monitoring, diagnostics, workload simulation, and reporting. The article also details effective bo

This article guides users through downloading Oracle Database. It details the process, emphasizing edition selection (Express, Standard, Enterprise), platform compatibility, and license agreement acceptance. System requirements and edition suitabil

This article explores Oracle Database client tools, essential for interacting with Oracle databases without a full server installation. It details commonly used tools like SQL*Plus, SQL Developer, Enterprise Manager, and RMAN, highlighting their fun

This article examines Oracle's default tablespaces (SYSTEM, SYSAUX, USERS), their characteristics, identification methods, and performance implications. It argues against relying on defaults, emphasizing the importance of creating separate tablespac

The article explains how to create users and roles in Oracle using SQL commands, and discusses best practices for managing user permissions, including using roles, following the principle of least privilege, and regular audits.

This article details Oracle Data Masking and Subsetting (DMS), a solution for protecting sensitive data. It covers identifying sensitive data, defining masking rules (shuffling, substitution, randomization), setting up jobs, monitoring, and deployme


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Dreamweaver CS6
Visual web development tools

Zend Studio 13.0.1
Powerful PHP integrated development environment

SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

Atom editor mac version download
The most popular open source editor
