plan digitizer

Introduction: This article provides a comprehensive overview of the relevant concepts of the Oracle execution plan, accessing data access methods, linking between tables, and more. and a summary and overview, easy to understand and memory! +++ Directory---one. Related concept ROWID concepts recursive SQL concept predicate (predicate) driving table (Driver table) probed table (probed table) combined index (Concatenat Ed index) optional (selectivity) Tw

Dbms_xplan is a package that Oracle provides to view SQL plans, including execution plans and interpretation plans, and I used the set autotrace command when I looked at the SQL execution plan, but now it seems that Dbms_ The Xplan package gives a simpler way to get and display a plan. These 5 functions correspond to different display plans, and the Dbms_xplan package can not only get an interpretation

Label:Explain the difference between a plan and an execution planWith the development tools that explain the output of the plan, such as the widespread use of toad, generating an interpretation plan becomes quite simple. Rather than simply getting the execution plan.Explain the planEXPLAIN plan is used to display the e

Label:The parameter sniff problem is to reuse the execution plan generated by other parameters, leading to the non-optimization of the execution plan by the current parameters. Presumably familiar with the data of the students should know that the most typical problem of producing parameter sniff is the use of parameterized SQL (or stored procedures using parameterized), if there is uneven distribution of d

A cache plan can be divided into two classes: the compiled plan and the execution context. The former is shared with all users, and the latter is for a specific user, and it contains information about the specific parameters of a user executing the plan. There are four types of compiled plans, which can be viewed through the following statements: SELECT * FROM s

The Webform+easyui-based business management system formation journey-construction planning arrangement, mainly introduces the whole construction plan list and the editing interface.Check out the construction plan below (Ⅰⅱⅲⅳⅴⅵⅶⅷ)Ⅰ, Construction Plan inquiry The Construction plan query interface, as shown in.Clic

The Oracle execution plan has 5 types of index scans, depending on the type of the index and the where constraints, namely, index unique scans (the index unique scan), index range scans (the index range Scan), index full scan Scan), Indexing Quick Scan (index fast full scan) index skip-Scan (index skip scan).1, the index unique Scan (index unique scan)Finding a value through a unique index often returns a single rowid. Oracle often implements a unique

. Explanations of the columns in the execution plan: Column Name Explain Special Instructions Id The identifier for the Select Select in the query of the ordinal, the same sequence number is indicated to be a group, the larger the number of the first execution, the lower the number of the outer layer, if the union result is null, the same group will be executed from top to bottom in the order.

If you want to analyze a performance problem with a SQL, you usually have to look at the SQL execution plan to see if there is a problem with every step of the SQL execution. If a SQL is normally performed well, but one day suddenly performance is poor, if the system resources and blocking reasons, then the basic can be concluded that the implementation of the plan. Understanding the execution

Topic: Where do you plan to go in your career? -- The second discussion minutes of agile individual A1 Group Participants:Zhang Jun (Organizer), Mai Cui ran, Zhang Xiaoyu (Recording), Zhang chunchao, Xu shuifeng, and Xu xiufeng Discussion time:To Discussion form:YY voice communication Step 1: share your personal experience Summary:Are you happy to work? Do you think it is a pain to go to work every day? Do you want to know what you really

Startup phase Figure 3-1 tasks and artifacts in the startup phase Product research Study the status of the product field to provide a basis for project demonstration. The study covers: Current Situation and Prospects in the product Field Business models and business processes in the product Field Product value and Profitability Product Features and complexity Technical feasibility study Study the product impleme

Abstract: developing a website promotion plan is also a website promotion strategy. The promotion plan is not only a promotion action guide, but also a measure of whether the promotion effect meets the expected objectives. The website promotion plan should include at least three basic content: the stage objectives of website promotion; the website promotion metho

To improve the efficiency of database operation, we need to hit the execution plan as much as possible to save the running time. To improve the efficiency of database operation, we need to hit the execution plan as much as possible to save the running time. 1 Overview The essence of SQL is a series of pseudo-code, which expresses what is done, not what it means. Like other languages, SQL statements mus

Label:Recently often see the word "parameter sniffing", read a few articles, so I try to do a test to deepen the impression! Go to the official website to download the database: AdventureWorks2012 Direct Test it! Find a few familiar tables to associate with, Use ProductID as a condition to find two IDs returns a value that has a large difference in the number of rows. productid=870 (4688 lines) productid=897 (2 lines)"Test One"---First empty the plan

Scope of application: Windows 8 Consumer Preview version Knowledge Point Analysis: Change power Plan settings under Windows 8 system Operation Steps: 1. In Control Panel, change the upper-right corner view to large icons, find power options, or open system and security directly under categories to find power options; 2. In power Options, select the right "change power Plan" to do power

1. In Control Panel, change the upper-right corner view to large icons, find power options, or open system and security directly under categories to find power options. See figure below 2, in the "Power Options" to select the right "change power Plan" to carry out power plan modification. See figure below 3, in the "Edit plan settings" can

Win7 system users create some power plans on their computers, and when they do not want to use these power plans later, how can they be removed? Now it's a simple way to teach you a small story. Interested users can experience a look! 1. Click the "Power" icon in the lower right corner of the taskbar and select "More Power Options". 2, then in the Open interface, select the system's default power Plan "energy saving", "balance (recommended)", "High

that a system of SQL execution plan incorrectly results in a sharp increase in logical reading. Analysis of AWR reportsthe logical reading of the top SQL at the time of failure can see that CDWJDD67X27MH SQL logic reads abnormally largeAnalysis of CDWJDD67X27MH logical reading in normal time point AWR reportBy comparison, we can find that the number of CDWJDD67X27MH statements in the two awr is almost the same, but the single logical reads from 800

Bad SQL not only directly affects the SQL response time, but also affects the performance of the DB, resulting in other normal SQL response time to become longer. How to write good sql, learn to see the implementation plan is essential. Let me briefly talk about the implementation of MySQL plan, only listed a number of common situations, I hope to help. Test table structure: Copy Code code as follows

The next article is to record their own blind spots, but also reveal their own development process (may not be developed, can only be said to be blind). Of course, some blind spots are also in the process of work and exploration slowly some, now also willing to carry forward the dedication of the blog park, to come out and share with you.At the beginning of the work, always with their own "high-tech" work, and feel special, often in front of others to say something to make others feel tall on th