how to optimize sql query using execution plan

database engine reduces the current overhead to push it to zero. The database engine checks the execution plan again until enough execution plans are deleted to meet memory requirements. If there is insufficient memory, the execution plan can increase or decrease its overhe

subsequent execution does not need to be re-compiled, and the final execution10000The total number of queries is only used1Second. 2 , Check and analyze SQL Server Execute the execution plan in the cache Through the above introduction, we can see thatSQLThe memory used by the cache. You know.SQL ServerThe conten

graphical execution plan (http://msdn.microsoft.com/zh-cn/library/ms178071.aspx) is a good start. Other useful resources includeGrant Fritchey's book,SQL Server execution plan (available as a free ebook) andFabiano Amorim about the various operators found in the

Tags: purpose sharing work tar Mic HTTP ISS archive technology shareoutline: Objective to describe the approximate use of execution plans in SQL Server, which can be useful when a query performance bottleneck is encountered, and with a more detailed learning document and plan, which the reader can follow as I

displaying the query plan are as follows: Requires a graphical query plan, using the SQL Editor toolbar of the Administration studio, the show estimated execution

reused; 3.3 Modify Sql:select * from Employee (add a space after the SELECT) to execute and view the execution plan The result is a new execution plan that SQL Server considers to be two different SQL statements and establish

executed, which is generated by the query optimizer (Query Analyzer) and is an efficient, least expensive scenario, which is the execution plan. I do not know the query optimizer can read before I write a blog: the T-SQL Advanced

from V$sqlarea where Sql_text like ' select Object_ name from s% '; no rows selectedFrom the above query results can be seen that the command did delete the S1 corresponding to the SQL execution plan, but also the table S2 corresponding SQL

it still needs to generate an adhoc execution plan for each sentence query. So it is not the most effective way to reduce the ratio. Using sp_executesql can increase execution plan reuse more effectively. 5. Stored Procedure It

ordersview, the definition code is preceded by. Let's take a look at what the execution plan would be if we were to use this view directly:As you can see from this view, SQL Server does a full table scan of table orders and should be inefficient. Take a look at the following query:As you can see from this execution

minor changes, such as changes in the Time field, can still reuse the cached execution plan, to avoid the impact of recompilationOf course I'm just a simple example here, and the actual application is much more complicated than thisFor example, the distribution of the special multi-data has two characteristics, the first distribution of the indicator is not only one, the second distribution of uneven data

statement:SET STATISTICS time OFF;This option is useful when you need to analyze the performance of a single statement. Metrics are different when you need to use batch mode to run statements. The value of the Sysdatetime function is saved and written to a table before the query. Note that the time format returned by this function is DATETIME2, which can be accurate to 100 nanoseconds. The accuracy of this function depends on the computer hardware an

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

the quality of an execution plan. 2, for the table connection order, in most cases using nested loops, especially in the case of good index availability, the use of nested loops is best, but when Oracle discovers that the data table needs to be accessed large, the cost of the index is high, or no suitable index is available, consider

, To determine the quality of an execution plan. 2, for the table connection order, in most cases using nested loops, especially in the case of good index availability, the use of nested loops is best, but when Oracle discovers that the data table needs to be accessed large, the cost of the index is high, or no suitable index is available, consider

try again. Refine view Query In other words, the optimized view query, although the view is also defined by a query statement, is essentially a query, but it and the general query in the optimization, there is a difference. The main difference here is that although the vi

although the view is defined by a query statement, it may not make much sense to parse the query definition, because the view is not used directly, but before it is used, it is preceded by a where statement, or in other statements for use by the FROM clause. Here's an example of a view Ordersview in my demo database, defined in front of the code. Let's take a look at what kind of

Tags: Microsoft wildcard scalar SOF ZMQ system size Server sumFirst, how to open the execution plan? Open "Include Actual execution Plan" (shortcut key: ctrl+m) in Microsoft SQL Server Management Studio, execute SQL statement to s

Tags: style blog http io color OS using SP strongOriginal: "MS SQL" analyzes SQL performance by execution planHow to know the execution efficiency of a SQL statement, only know the following 3 kinds:1. Analysis of disk activity vo

Let's first use a small table to explain which aspects should be paid attention to in the Oracle execution plan. HR @ orcl> set autotrace traceonlyhr @ orcl> select * from t; when fuzzy comparison of the two SQL statements, we recommend that you first check the following two values: cost (% CPU): CPU cost, this value must be an algebraic sum. For example, 3 + 3 =