Oracle Partition Table execution plan, oracle execution plan
Partition tables have many advantages: they are big, small, and small. With parallel use, loap can often improve the performance by dozens or even hundreds of times. Of course, poor table design can also be counterproductive, and the effect is worse than that of normal tables. To better use a partitioned table, let's take a look at the execution
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The first figure shows the execution plan
Inaccurate MySQL execution plan-Overview, mysql execution plan
The execution plan for the Mao MySQL optimizer is often inaccurate, but not optimal (cpu + io )???
Too many factors ::
The information of information_schema is regularly refreshed. In many cases, it is not the most authentic, or even the difference is very large (when it is not a mountain peak, make
There are many ways to view execution plans. I will introduce them one by one in my blog in the future. This article describes the first method. You can use the explain plan command to view the execution plan.1. log on to the database with an hr user[Oracle @ ENMOEDU ~] $ Sqlplus hr/oracle @ ENMOEDUSQL * Plus: Release 11.2.0.3.0 Production on Thu Apr 10 00:11:00 2014Copyright (c) 1982,201 1, Oracle. All rig
Framework Plan essay I. Background and vision, Framework Plan essay vision
It has been 11 years since I registered my blog. In fact, I forgot how I registered my blog. Afterwards, I never remembered writing my own blog.
Recently, I am working on my own architecture plans, and I am gradually guiding the back-up for coding, and I plan to write my own. net-based ORM
Explanation of MySQL execution plan, mysql execution planExplain syntax
Explain select ...... Variant: 1. explain extended select ...... Decompile the execution plan into a SELECT statement and run show warnings to obtain the query statement optimized by the MySQL optimizer. 2. explain partitions select ...... Used to EXPLAIN the Partition Table
Information contained in the execution
View the Oracle Execution Plan and the oracle execution plan1. PL/SQL explain Plan window
Advantages:
Disadvantage: limited information2. explain_plan
It is easier to optimize a sentence.3. sqlplus
Run the following command in Sqlplus:
Set autotrace on
Select * from emp;
After the data is displayed, follow the execution plan:
The advantage of this s
,Let's build this one. Index: CREATE index idx_col2_col3 on Teststatistics(col2,col3)Executes a query that is estimated to be 4127.86 rowsThen drop the index above and continue creating an index: Create index idx_col3_col2 on Teststatistics(col3,col2)Note that the order of COL2 and COL3 is inconsistentContinue execution of the above query (the query condition is unchanged, the data is unchanged, only the index column order has changed), this time is estimated to be 2414.91 row Query conditions,
To add, if you want to do a SQL automatic audit tool, where can I start?1, through the Sql*plus tool in the explain PLAN for judgment, the use of Dbms_xplan. Display displays.2, through the Sql*plus tool in the SET autotrace command display3, Sql_trace, in the database global (performance problem, is basically a waste of options), or to the current session definition Sql_trace, or use Dbms_system. Set_sql_trace_in_session gets the sql_trace of the oth
Label:When you create a new plan, remember that the execution plan requires the SQL Agent service (SQL Server Agent) to also open the Maintenance dialog box: "SQL Server has blocked access to the process ' dbo.sp_set_sqlagent_properties ' of component ' Agent XPs ' because this component has been shut down as part of this server's security configuration." SQL Server blocked access to the process ' dbo.sp_se
Content contained in the website construction plan: Key Points of the website construction plan
The success or failure of a website has an extremely important relationship with the website planning before the website is built. Before establishing a website, you should clarify the purpose of website construction, determine the functions of the website, determine the website size, investment costs, and conduc
Team plan (4.20), team plan 4.20
Completion: Understand the as interface and basic functions
Develop basic personal module plan
And link: Run helloworld: http://jingyan.baidu.com/album/90895e0fce970264ec6b0bf2.html? Picindex = 5
As introduction to knowledge: http://blog.csdn.net/yanbober/article/details/45306483
Plan
Tags: style color get C strong fileAutotrace is an sql*plus feature that automatically tracks the generation of an execution plan for SQL statements and provides statistics about the processing of the statement. Sql*plus Autotrace can be used instead of SQL Trace, the benefit of autotrace is that you do not have to format the trace file, and it automatically displays the execution plan for the SQL statement
The following execution plan is printed out. Many friends still don't know. In fact, there are only three statements:
Explain plan for the SQL statement you want to view; commit; select * from table (dbms_xplan.display );
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First, let us know a principle,When you look at the execution plan, start from the first l
Create a power plan what to choose
To create a power plan is a timing function, such as how long we do not use the computer automatically into the screen saver or longer without the system automatically sleep state.
How do I create a power plan? (Win8.1)
1. Click the "Start" option, as shown below.2. Select the "Control Panel" option to open the entry details
2. Table join(Table join)
So far, we have been dealing with a single table. Let's look at the connections in the query. The following query gets the employee information and connects firstname and lastname, so that the returned information is more friendly.
SELECT e.[Title], a.[City], c.[LastName] + ', ' + c.[FirstName] AS EmployeeNameFROM [HumanResources].[Employee] eJOIN [HumanResources].[EmployeeAddress] ed ON e.[EmployeeID] = ed.[EmployeeID]JOIN [Person].[Address] a ON [ed].[Ad
Create your own oracle interpretation plan and oracle interpretation plan
1. Explain the plan
When an explain plan is used to generate an expected execution plan for a query, the output includes the following:
Each table accessed by SQL;
Method for accessing each table;
The
Cost Calculation Method in execution plan, execution plan cost
Concept:
Blevel: Binary Height = index height-1
Clustering_factor: Cluster factor, number of blocks in the table to be scanned after index scan, clustering_factor
Index scan calculation formula:Cost =
Blevel +Ceil (leaf_blocks * Valid tive index selecti.pdf) +
Ceil (clustering_factor * Valid tive table selecti.pdf)
The test is performed unde
raw service object.Mservice =NewMessenger (service); Mcallbacktext.settext ("Attached."); //we want to monitor the service for as long as We are//connected to it. Try{Message msg= Message.obtain (NULL, messengerservice.msg_register_client); Msg.replyto=Mmessenger; Mservice.send (msg); //Give It some value as an example.msg = Message.obtain (NULL, Messengerservice.msg_set_value, This. Hashcode (), 0); Mservice.send (msg); } Cat
App->activity->custom Dialog Example using Activity to implement a custom dialog boxThe class customdialogactivity itself is nothing special. The key point is its definition in Androidmanifest.xml: android:label=" @string/activity_custom_dialog " Android:theme = "@style/theme.customdialog"> Customdialogactivity uses a custom Customdialog style (Theme). Android apps can use a custom interface style (Theme), Theme as a set of related style definitio
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