国产av日韩一区二区三区精品,成人性爱视频在线观看,国产,欧美,日韩,一区,www.成色av久久成人,2222eeee成人天堂

Home Database Oracle How to read the oracle explanation plan

How to read the oracle explanation plan

Apr 11, 2025 pm 11:21 PM
oracle access

Oracle Interpretation Plan is a detailed description of the SQL statement execution process. To get an explanation plan, use the EXPLAIN PLAN command. The Interpretation Plan shows a series of operations, each containing the type of operation, the object name, the number of rows and bytes processed, and the cost. Operations such as TABLE ACCESS FULL, INDEX RANGE SCAN, and NESTED LOOPS show how the query is performed. The cost field identifies performance bottlenecks, and optimization measures such as creating indexes or adjusting predicates can resolve them.

How to read the oracle explanation plan

How to interpret Oracle Interpretation Plan

Oracle Interpretation Plan is information provided by the database about the execution plan of SQL statements. It provides in-depth insights into how statements are executed and why they are executed in this way. Understanding how to interpret interpretation plans is critical to optimizing query performance.

Step 1: Get an explanation plan

To get an explanation plan, you can use the EXPLAIN PLAN command:

 <code class="sql">EXPLAIN PLAN FOR <sql statement>;</sql></code>

Step 2: Understand the planning structure

An explanation plan consists of a series of rows, each representing an operation in the query execution. The plan tree is rendered from top to bottom, and the root node represents the main operation of the query.

Step 3: Key fields

Each plan line contains the following key fields:

  • Operation: Operation type, such as TABLE ACCESS FULL, INDEX RANGE SCAN
  • Object Name: The name of the object participating in the operation, such as a table or index
  • Rows: Estimate the number of rows processed in this operation
  • Bytes: Estimate the number of bytes processed in this operation
  • Cost: Estimated cost of operations

Step 4: Interpret the operation

It is crucial to understand the meaning of each operation:

  • TABLE ACCESS FULL: Scan all rows from the table.
  • INDEX RANGE SCAN: Use index to scan a subset of the table.
  • NESTED LOOPS: Check two tables row by row.
  • CARTESIAN PRODUCT: Match all rows in two tables.

Step 5: Identify Performance Bottlenecks

The cost field is the key to identifying performance bottlenecks. High-cost operations indicate the need for optimization.

Step 6: Optimize Query

Once the performance bottleneck is identified, the problem can be solved by optimizing the query. For example, you can create or rebuild the index, adjust the query predicate, or use a different join type.

Example:

Consider a query that contains the following explanation plan:

 <code class="text">Operation | Object Name | Rows | Bytes | Cost -------------------------------------------------------- TABLE ACCESS FULL | t1 | 10000 | 50000 | 10 INDEX RANGE SCAN | t2 | 100 | 1000 | 2 NESTED LOOPS | | 10 | 100 | 1</code>

This plan shows that scanning all rows from Table t1 (TABLE ACCESS FULL) is the most expensive operation. Optimizing queries by creating indexes on t1 can reduce costs and improve performance.

The above is the detailed content of How to read the oracle explanation plan. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

10 latest tools for web developers 10 latest tools for web developers May 07, 2025 pm 04:48 PM

Web development design is a promising career field. However, this industry also faces many challenges. As more businesses and brands turn to the online marketplace, web developers have the opportunity to demonstrate their skills and succeed in their careers. However, as demand for web development continues to grow, the number of developers is also increasing, resulting in increasingly fierce competition. But it’s exciting that if you have the talent and will, you can always find new ways to create unique designs and ideas. As a web developer, you may need to keep looking for new tools and resources. These new tools and resources not only make your job more convenient, but also improve the quality of your work, thus helping you win more business and customers. The trends of web development are constantly changing.

How to uninstall MySQL and clean residual files How to uninstall MySQL and clean residual files Apr 29, 2025 pm 04:03 PM

To safely and thoroughly uninstall MySQL and clean all residual files, follow the following steps: 1. Stop MySQL service; 2. Uninstall MySQL packages; 3. Clean configuration files and data directories; 4. Verify that the uninstallation is thorough.

Oracle's Role in the Business World Oracle's Role in the Business World Apr 23, 2025 am 12:01 AM

Oracle is not only a database company, but also a leader in cloud computing and ERP systems. 1. Oracle provides comprehensive solutions from database to cloud services and ERP systems. 2. OracleCloud challenges AWS and Azure, providing IaaS, PaaS and SaaS services. 3. Oracle's ERP systems such as E-BusinessSuite and FusionApplications help enterprises optimize operations.

How to understand DMA operations in C? How to understand DMA operations in C? Apr 28, 2025 pm 10:09 PM

DMA in C refers to DirectMemoryAccess, a direct memory access technology, allowing hardware devices to directly transmit data to memory without CPU intervention. 1) DMA operation is highly dependent on hardware devices and drivers, and the implementation method varies from system to system. 2) Direct access to memory may bring security risks, and the correctness and security of the code must be ensured. 3) DMA can improve performance, but improper use may lead to degradation of system performance. Through practice and learning, we can master the skills of using DMA and maximize its effectiveness in scenarios such as high-speed data transmission and real-time signal processing.

How to add your WordPress site in Yandex Webmaster Tools How to add your WordPress site in Yandex Webmaster Tools May 12, 2025 pm 09:06 PM

Do you want to connect your website to Yandex Webmaster Tools? Webmaster tools such as Google Search Console, Bing and Yandex can help you optimize your website, monitor traffic, manage robots.txt, check for website errors, and more. In this article, we will share how to add your WordPress website to the Yandex Webmaster Tool to monitor your search engine traffic. What is Yandex? Yandex is a popular search engine based in Russia, similar to Google and Bing. You can excel in Yandex

How to fix HTTP image upload errors in WordPress (simple) How to fix HTTP image upload errors in WordPress (simple) May 12, 2025 pm 09:03 PM

Do you need to fix HTTP image upload errors in WordPress? This error can be particularly frustrating when you create content in WordPress. This usually happens when you upload images or other files to your CMS using the built-in WordPress media library. In this article, we will show you how to easily fix HTTP image upload errors in WordPress. What is the reason for HTTP errors during WordPress media uploading? When you try to upload files to Wo using WordPress media uploader

MongoDB vs. Oracle: Choosing the Right Database for Your Needs MongoDB vs. Oracle: Choosing the Right Database for Your Needs Apr 22, 2025 am 12:10 AM

MongoDB is suitable for unstructured data and high scalability requirements, while Oracle is suitable for scenarios that require strict data consistency. 1.MongoDB flexibly stores data in different structures, suitable for social media and the Internet of Things. 2. Oracle structured data model ensures data integrity and is suitable for financial transactions. 3.MongoDB scales horizontally through shards, and Oracle scales vertically through RAC. 4.MongoDB has low maintenance costs, while Oracle has high maintenance costs but is fully supported.

MySQL vs. Oracle: Licensing, Features, and Benefits MySQL vs. Oracle: Licensing, Features, and Benefits May 08, 2025 am 12:05 AM

The main difference between MySQL and Oracle is licenses, features, and advantages. 1. License: MySQL provides a GPL license for free use, and Oracle adopts a proprietary license, which is expensive. 2. Function: MySQL has simple functions and is suitable for web applications and small and medium-sized enterprises. Oracle has powerful functions and is suitable for large-scale data and complex businesses. 3. Advantages: MySQL is open source free, suitable for startups, and Oracle is reliable in performance, suitable for large enterprises.

See all articles