how to optimize sql query using execution plan

is large, also must see what in the condition is what, later returns the data. In the case of this SQL statement, the efficiency difference is not very large. You can look at the I/O statistics: Table Scan: 　　 Clustered Index Scan: 　　 This is beyond the scope of this article, the efficiency is not in the context of this article, this article only consider the differences between the various scans, and why the resulting.3. Clustered Index LookupCluste

(procedure/ Function/package), T (TYPE), R (TRIGGER), and Q (SEQUENCE) www.2cto.com Using this method, you can precisely delete a SQL from the shared pool, This allows Oracle to regenerate the execution plan for this SQL. This method only targets a single

Tags: proc ORM scan SSE query condition exec pre res loop1. The test data is as follows:Sql> select * from T1;A | B | C---+----+---1 | 10 | 12 | 20 | 23 | 30 | 34 | 40 | 45 | 50 | 56 | 60 | 6(6 rows)Sql> select * from T2;A | B | D---+----+---1 | 10 | 12 | 20 | 23 | 30 | 3(3 rows)2. Parse the example SQL as follows:SELECT *From (SELECT * from t1 where C >= 2) T1 L

look at the I/O statistics:Table Scan:　　Clustered Index Scan:　　This is beyond the scope of this article, the efficiency is not in the context of this article, this article only consider the differences between the various scans, and why the resulting.3. Clustered Index LookupClustered Index Lookup: Scans a specific range of rows in a clustered index.See execute the following SQL statement:'73164' The implementation

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

accurate execution plan. Create a statistic for the condition by using the following statement Statistics businesstablefilterstatistics on businesstable (BUSINESSSTATUS1,BUSINESSSTATUS2) where BusinessStatus1= andBusinessStatus2=--withfullscan After the statistics are created, a statistic that you just created is added to the table. Now look at the

Query Optimizer will navigate directly to the desired data row through the index to complete thePolling Of course, the premise is that you cannot have group by operations in query. If you use min () or Max ()Waiting◇using Filesort: When we include an order by operation in our query and cannot use the index to complete

primary key not back to the tableCase 3([emailprotected]) [dbt3]> DESC SELECT *, LineItem, where, l_shipdate Union result merges two tables using the temporary, with the temporary table, the union will go heavy, so to build a temporary table, with a unique index on it, there are two indexes, so that a SQL can only use one index is not rightCase 4([emailprotected]) [employees]> DESC Select, Emp_no, De

Summary of Oracle SQL Execution Plan and Analysis Oracle has multiple ways to obtain a query plan for an SQL statement, such as using the explain p