tuning oracle sql queries

Oracle scalar queries and their own defined functions are sometimes easier to use, and are often used by developers. Small amount of data does not matter. The amount of data is large and there are often performance problems.Here is a test to help you understand the scalar quantum query thoroughly. Sql> CREATE TABLE A (ID int,name varchar2 (10)); Table created.

One of the practical skills that can greatly improve the performance of SQL TUNING optimization. When we perform SQL optimization, we often encounter the need to sort a large number of datasets and then retrieve the first part of the results from the sorted set. In this case, when we write SQL statements according to t

cases. First, if the data block of the selected row has been read to the data buffer, the server process will directly pass the data to the client instead of querying the data from the database file. If the data is not in the buffer, the server process queries the relevant data from the database file and puts the data into the data buffer. Note that many types of cache are defined in the Oracle database.

fromV$thread T, V$parameter vWHEREV.name= 'Thread' and(V.value= 0 ORt.thread#=To_number (v.value))) I, (SELECTVALUE fromV$parameterWHERENAME= 'user_dump_dest') D;3.2 Using the Tkprof command to beautify the generated trace fileHere is what I often use, for more detailed instructions on the tkprof command, you can see the tkprof command directly enter.Tkprof xxx.trc xxx.txt Explain=system/Oracle sys=nReference URL: http://www.eygle

"Performance Tuning" Oracle AWR reporting metrics full resolution What is AWR? ===================================================================================================== AWR (Automatic workload Repository) A bunch of historical energy data, placed on the Sysaux table space, AWR and Sysaux are all 10g, are the key features of Oracle

Oracle and is not configured to connect to SQL Server.The idea is to use a transparent gateway in Oracle, first in Oracle's installation name, Oracle Net Services and Oracle Transparent gateways, and select Oracle under this key

oracle| Data Oracle relational database management system is a popular relational database in the world, it is an extremely powerful, flexible and complex system, it is said that in the use of Oracle should be the idea, that is in the SQL can almost achieve any idea. The following is a method of using

. Database writer contention alertCheck Points for the total length of bad queries, write requests, and database writer DBWR. When the Write Request Length is greater than 3 or greater than the number of DBWR checkpoint waits, you need to adjust the database writer process. Data Dictionary failure rate alertYou will be prompted for too many requests for the data dictionary metadata. Sometimes you can addShared_pool_sizeinit.oraThe value of this para

server process will actually execute this SQL statement. This statement can also be executed in two cases. First, if the data block of the selected row has been read to the data buffer, the server process will directly pass the data to the client instead of querying the data from the database file. If the data is not in the buffer, the server process queries the relevant data from the database file and put

queries that reference the distributed partitioned view name to run on any member server. The system operates as if each member server has a copy of the original table, but there is only one member table and one distributed partitioned view on each server. The location of the data is transparent to the application. 11. Rebuild the index DBCC REINDEX, DBCC INDEXDEFRAG, shrink data and log DBCC SHRINKDB,DBCC shrinkfile. Sets the auto-shrink log. For la

placed at the end of the SQL statement.2.14 What you should knowBefore you learn the next chapter, check to see if you have mastered the following: 1, What is the relational database key selection (selection) operation. 2 . How to use the WHERE clause to qualify the selected data row. 3,6 common comparison operators (Operators). 4, How to construct the conditions in the WHERE clause. 5. Between and and in comparison operators (Operators). 6. Use of t

Oracle query table space usage -- Query table space usage SELECTUPPER (F. TABLESPACE_NAME) tablespace name, D. TOT_GROOTTE_MB tablespace size (M), D. TOT_GROOTTE_MB Oracle queries table space usage-queries table space usage select upper (F. TABLESPACE_NAME) tablespace name, D. TOT_GROOTTE_MB tablespace size (M), D. TOT

) avgsal from EMP Group by DEPTNO) A1 where A2.deptno=a1.deptno and A2.sal > a1.avgsal; Summary: When a subquery is used in the FROM clause, the subquery is treated as a view, so it is called an inline view, and when a subquery is used in the FROM clause, the subquery must be given an alias. --You can use as for a column alias, but aliases for tables, views, and subqueries cannot be used as Page out Oracle's paging is the most complex, with 2 sub-queries