oracle sql performance analyzer

) function. Distinct requires a sort operation, while the others need to perform at least two sorting. Typically, SQL statements with union, minus, and intersect can be overridden in other ways. If your database is well-sort_area_size, using union, minus, intersect can also be considered, after all, they are very readable()optimize GROUP By:Increase the efficiency of the group BY statement by filtering out unwanted records before group by. The followi

(rollback segments) is used to hold information that can be recovered. If you do not have a COMMIT transaction, Oracle restores the data to the state it was before it was deleted (exactly before the delete command was executed) and when the truncate is applied, the rollback segment no longer holds any recoverable information. When the command runs, The data cannot be restored. So very few resources are invoked and execution times are short. (Translat

To facilitate their own work, the use of Delphi developed a database query analysis management tools. Share to everyone, the following characteristics:1. Due to the use of ADO connection, the theory supports all databases such as SQL Server, Access, MySQL, Oracle, etc.2. Support SQL keyword automatic prompt3. Support automatic prompt for table name4. Support tabl

Tags: style blog http ar color OS using SP dataOriginal: SQL Server access Oracle Query performance Problem Resolution1. Questions　　The system has a module that needs to query the data in the Oracle database. It is now implemented by establishing a linked server.　　SQL Server

oracle| Performance | optimization 39. Always use the first column of the index If the index is based on multiple columns, the optimizer chooses to use the index only if its first column (leading column) is referenced by the WHERE clause. Translator by: This is also a simple and important rule. See the following examples. Sql> CREATE TABLE Multiindexusage

increasing number of users and data volumes. Scalability is limited. Oracle Parallel servers extend the capabilities of Windows NT by enabling a set of nodes to share work in the same cluster, providing high-availability and highly scalable clusters of solutions. If WindowsNT does not meet the needs, users can move the database to UNIX. DB2 DB2 has a good parallelism. The DB2 extends the database management to the parallel, multi-node environment.

oracle| Performance | optimization 27. Selection of the base table The underlying table (driving table) refers to the table that is first accessed (typically accessed as a whole table scan). Depending on the optimizer, the selection of the underlying table in the SQL statement is different. If you are using a CBO (cost BASED OPTIMIZER), the optimizer checks t

oracle| Performance | optimization 31. Force Index Invalidation If two or more indexes have the same level, you can force the Oracle optimizer to use one of them (through which the number of records retrieved is low). Example: SELECT ename From EMP WHERE EMPNO = 7935 The index on DEPTNO + 0 =/*deptno will fail. and Emp_type | | The index on the ' =

The former is easy to locate. All operating systems allow us to look at CPU-intensive tasks. These tasks can be traced back to a specific user, a specific application module. CPU-intensive modules are generally caused by poor code and/or structure, rather than poor performance SQL. Once you've identified the module, you have to try to make it more efficient. One possible solution is to take some processing

oracle| Performance | optimization 24. Analyze SQL statements with explain plan EXPLAIN Plan is a good tool for analyzing SQL statements, and it can even parse statements without executing SQL. By analyzing, we can see how Oracle