how to optimize sql query using execution plan

Tags: factor auto-generated program development OTA UI Images customer plan When doing a patrol on an Oracle server, using the following SQL to find the highest disk_read top SQL analysis, there are some anomalies in the parsing process that have an SQL statement, which make

implemented in a stored procedure, we use a undocument query hint directly on the statement, which causes the parallel cost threshold of the query to be reduced to 0, which forces the statement to go parallel and the statement execution time from 20 seconds to 5 seconds (note: Using the hash join hint is 7 seconds). T

following is a simple example showing the effect of using this hint, example T-SQL as shown in Listing 1: SELECT * from [adventureworks].[ Sales]. [SalesOrderDetail] A INNER JOIN [Sales]. SalesOrderHeader B on A.salesorderid=b.salesorderid Code Listing 1. The statement does not go in parallel by default and the execution

we use a undocument query prompt directly to the statement, forcing the parallel cost threshold for the query to be dropped to 0, forcing the statement to go in parallel, and the statement execution time from 20 seconds to 5 seconds (note: Use a hash join hint for 7 seconds). The following is a simple example showing the effect of

on the statement, which causes the parallel cost threshold of the query to be reduced to 0, which forces the statement to go parallel and the statement execution time from 20 seconds to 5 seconds (note: Using the hash join hint is 7 seconds). The following is a simple example of the effect of using this hint, as shown

ObjectiveWe talked about the effect of clustered indexes on nonclustered indexes and the performance optimizations that the database has been emphasizing, so we'll take a look at the index to see what the query execution plan is, what the short content is, and how to understand it.View query

SQL Profile provides other information except system statistics and object (table and index) statistics for an SQL statement, such as the running environment and more accurate statistics, to help the optimizer select a more suitable execution plan for SQL statements.SQL Prof

Sm66 can view the runningProgramAnd execution time.St04 can monitor many sessions,Click: Detailed analysis list. You can select an analysis and monitoring session. For example, you can select an oracle session to view the SQL statements being executed.You can click the SQL statement to be monitored to go to the details page. Click the

1 withQs as(2 SelectCp.objtype asObject_type,/*type*/3 db_name(st.dbid) as [Database],/*Database*/4Object_schema_name (St.objectid,st.dbid) as [Schema],/*Architecture*/5 object_name(st.objectid,st.dbid) as [Object],/*Object Name*/6 Convert(Char( -), Qs.creation_time, -) asPlan_creation,/*Scheduled build time*/7 Convert(Char( -), Qs.last_execution_time, -) asLast_execution,/*Last Execution Time*/8 Qs.plan_generation_num

Tags: style blog class tar ext colorAfter a piece of SQL code is written, you can initially predict the performance of the SQL at run time by looking at the SQL execution plan, especially if you find that the SQL statement is inef

STATISTICS.SET AUTOTRACE onIncludes both the optimizer execution path and the SQL statement execution statistics.SET AUTOTRACE traceonlyLike SET AUTOTRACE on, but suppresses the printing of the user's query output, if any.Note: If the set autotrace on statement is executed, the following

Objective An analysis of the impact of SQL Server focused indexes on nonclustered indexes we talked about the effect of clustered indexes on nonclustered indexes, the performance optimization that the database has been emphasizing, so this section we talk about using the index to see how the query execution

Experiment with SQL profile fixed execution plan Oracle has outlines before 10 Gb, and SQL profile after 10 Gb is one of the new features. Outlines is insufficient for SQL statements that are not bound to variables. The following is the experiment process. -- 1. preparatio

connections is much faster than looping nesting. From the principle of merging joins it is not difficult to imagine that merging connections first requires both parties to be orderly. And the condition of the join is equal to the number. Since two input conditions are already in order, it is not difficult to see why the merge join is only allowed to be equal to the join after a row is compared from each input set, equal returns, and unequal discards. We can see this principle from the icon in F

Analysis of SQL Server's focus on using indexes and query execution plans and SQL Execution plans Preface In the previous article "Analysis of the Impact of SQL Server focused indexes o

generates its actual execution plan when each query is running. Using showplan XML or showplan XML statistics profile to capture all execution plans will undoubtedly increase the burden on the server. These are not lightweight events. Even if showplan XML for

E-book URL The execution plan is simply the result calculated by the query optimizer, which indicates the most efficient way to execute the submitted query. The execution plan tells you how the

the ModifiedDate field, to become an index Seek treatment.Let's change the query statement by adding two additional fields to the SELECT:[SQL] SELECT ModifiedDate, SalesOrderID, Salesorderdetailid From Salesorddetaildemo WHERE modifieddate=' 2005-07-01 00:00:00.000 ' GO The execution pl