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Tags: find return cache response free temporary analysis CCache cannotSQL Server submits a user-submitted DML statement that, through a series of optimizations, produces a scenario that can be identified and efficiently "responded" by SQL Server using the Ctrl+m (actual execution plan) in Ctrl+l (estimated execution plan)Committing a DML statement (CRUD) can cause a series of activities.1. Activities that o

Tags: rom mit nested RAC row index driver who statementHow to read Oracle Execution Plan First, what is the implementation plan An explain plan is a representation of the access path, that's taken when a query is executed within Oracle. Second, how to access data At the physical level Oracle reads blocks of data. The smallest amount of data read is a single Orac

Read SQL Server query planRead Catalogue Begin How SQL Server looks for records SQL Server Join method More specific execution procedures Index statistics: The choice of the query plan is based on Optimizing View Queries Recommended Reading-MSDN Articles For SQL Server optimizations, tuning queries can be a common thing. Due to the optimization of the database, it is also a wide-ranging topic, so this article only

1. What is an execution plan) Execution Plan: the execution process or access path of a query statement in ORACLE.Ii. How to view the execution plan1: Press F5 under PL/SQL to view the execution plan. Third-party tools such as toad.Many people think that the PL/SQL Execution Plan can only see basic information such as

restriction condition of the application query. Therefore, if a large table has a restriction condition in the WHERE condition (such as the equivalence restriction ), this large table is also suitable as the driving table, so not only a small table can be used as the driving table. The correct statement should be based on the restrictions of the application query, returns the table with fewer row sources as the driving table. In the Execution Plan, i

Brief introduction: This article introduces comprehensively in detail OracleImplement the relevant concepts of the plan, access methods of accessing data, connections between tables, and so on. and a summary and overview, easy to understand and memory! +++ Directory---one. Concepts related to the concept of rowid recursive SQLConcept predicate (predicate) driving table (Driver table) probed table (probed table) combined index (concatenated Index) Opti

Label:This document is based on the relevant data collated, summarized, mainly on the Oracle database, to obtain the most authoritative and correct method of SQL statement execution plan, and also explained in detail the meaning of the options available in each method and how to use, so as to facilitate everyone and their daily work to consult the use of Because I did not find this blog support attachment upload function, need to PDF file format frien

1 Overview The nature of the SQL language is a string of pseudo code that expresses what to do rather than what to do. As in other languages, SQL statements need to be compiled before they can be run, so every SQL needs to be interpreted by the compiler to run (and also to optimize SQL). These steps require running costs, so there is something called an execution plan in the database, and the compiler will store the compiled SQL in the execution

Tags: parameter sniffThe 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 di

Label:Prior to the 11g version, the stored outlines (SQL Profile) feature was provided to save the SQL execution plan. In 11g, a new feature SQL plan management (SQL Management) feature was introduced to save SQL performance. The database automatically controls the evolution of the SQL execution plan, with SQL plan ba

To obtain the execution plan in the cache library, you can directly query the dynamic performance view v $ SQL _plan and v $ SQL _plan_statistics_all, but the more convenient method is SQL _id and sub- To obtain the execution plan in the cache library, you can directly query the dynamic performance view v $ SQL _plan and v $ SQL _plan_statistics_all, but the more convenient method is SQL _id and sub- 1