oracle performance analyzer

Oracle optimization of database memory parametersØ Oracle -related system kernel parameters Ø SGA,PGA parameter setting Oracle lower disk storage performance OptimizationØ File System selection (ext2/ext3,xfs,ocfs2) Ø Oracle ASM storage 1. What to know before optimizing

with each column. This allows you to reduce parsing time and reduce syntax errors caused by column ambiguity. Note: column ambiguity refers to the fact that because different tables in SQL have the same column name, the SQL parser cannot determine the attribution of this column when the column appears in the SQL statement. 2, the effect of the conditional order of the WHERE clause in Oracle on performance:

commit transaction, Oracle will recover the data to the State before the deletion (which is precisely the State before the deletion command is executed). When truncate is used, rollback segments no longer store any recoverable information. after the command is run, the data cannot be restored. therefore, few resources are called and the execution time is short. (The translator Press: truncate only applies when deleting the entire table, Truncate is D

(X.ROWID)From EMP X WHERE x.emp_no = e.emp_no);(9) Replace Delete with truncate:When you delete a record in a table, in general, the rollback segment (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 r

information that can be recovered. If you do not have a COMMIT transaction, Oracle restores the data to the state before it was deleted (to be exact, 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. (Translator Press: truncate only in Delete full

contain Bush in the employee table. The following SQL statement can be used: Select * from employee where last_name like '% Bush % '; Here, because the wildcard (%) appears at the beginning of the search term, the Oracle system does not use the last_name index. This situation may not be avoided in many cases, but it must be well understood. Using wildcard characters will reduce the query speed. However, when a wildcard appears at another position of

processing, those unnecessary indexes can slow down query response times. and the larger the table, the more serious the impact. Where to use the index: 1, to avoid using not on the index column,　 We want to avoid using not on indexed columns, not the same effect as using functions on indexed columns. When Oracle "encounters" not, he stops using the index instead of performing a full table scan. 2. Avoid the use of calculations on indexed column

unnecessary indexes can slow query response time. and the larger the table, the more serious the impact.The places to be aware of using indexes:1. Avoid using not on the index column,We want to avoid using not on indexed columns, and not to have the same effect as using functions on indexed columns. When Oracle "encounters" not, he stops using the index instead of performing a full-table scan.2. Avoid using calculations on indexed columns.Where claus

Test Hardware Description: The test is using my Love machine, configured as follows: cpu:c433 Memory: 128M HDD: Cool fish 2 generation 20G Test Software Description: WIN32 under Windows NT Server4,sp5,apache 1.3.12,php3.0.15 and Php4rc1,mysql 3.22.29,oracle 8.0.5 Linux under the Bluepoint linux1.0, Apache 1.3.12, Php4rc1,mysql 3.22.32 Test Code Description: Using a very simple table, MySQL and Oracle use

Using a very simple table, MySQL and Oracle use the same table structure, with only three fields, with the following structure: MySQL table structure: CREATE TABLE Board ( board_id smallint (6) not NULL auto_increment, Board_name char (+) is not NULL, Board_manager Char (20), PRIMARY KEY (board_id) ); Structure of Oracle: CREATE TABLE php_oracle. " BOARD " ("board_id" FLOAT, "Board_name" CHAR (+) is not NUL

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