Oracle

Oracle Execution Plan (5)-index range scan for cost costs-B-Tree Index   SQL> select * from T1 where a Row 599 has been selected. Used time: 00: 00: 00.03 Execution Plan ---------------------------------------------------------- Plan

I suddenly thought of testing the real I/O capabilities of the database. Although the hardware engineer has a set of methods to test iops, Oracle also launched the oraxxx test tool. in the actual application environment, iops is affected by table

How can I flash it back when I delete some table data? Some data is inserted to the table within 20 minutes.   Query by SCN number Select a, B, c, versions_xid, versions_starttime, versions_endtime,Versions_startscn, versions_endscn,

Oracle process session, cursor, and transaction relationship If you use top in Linux, you can see the running Oracle process. In addition to background processes, Oracle also has user processes.Both parallel and separate processes are enabled.

Alter table tab_large add col_new number (9) default 1; This statement will fill in the value of all records. For the field tab_large, there are about pieces of data, this step needs to be executed for several hours. You can change the statement:

Yesterday, I used a script to generate a bunch of index monitoring statements.   Select 'alter Index' | index_name | 'monitoring usage ;'From user_indexes;   Alter index IX_BASE_PROUSER_USER monitoring usage;Alter index IX_BASE_PROUSER_LOWEX

Function: two users, one of which has no data structure. User A can access all data of user B through user A. Only User A has the permission to read data and cannot see user B's data structure. User A can only query data. 1. Create read-only user: --

I. When do I need instance recovery? In shutdown normal or shutdown immediate, the so-called clean shutdown will automatically trigger the checkpoint and write the SCN record back. When a checkpoint occurs, the SCN is written to four places:   Three

1. Instructions Oracle Data is placed in the table, and the table segment (segment) is composed of extents, and extents is composed of blocks. Each block can store multiple rows. Oraclesga is composed of a DB buffer cache, which consists of default,

Some customers may encounter serious system performance problems due to unstable SQL Performance and sudden deterioration. For large systems, SQL Performance is unstable and sometimes deteriorated suddenly, which is a common problem. This is also a

There is a scenario where the user information table uses deletel; insert into select; To update user data. This causes keyword exceptions and data loss. There is no way to re-import data from another database; truncate table userinfo; insert into

Many parameters are required to optimize the Oracle database. Some of these parameters have a great impact on the system performance. These parameters are variable parameters. Variable parameters can be divided into two categories based on their

1. Host Name Planning: -- Before modification: # Public Network-(eth0)192.168.10.11 rac1192.168.10.12 rac2 # Private Interconnect-(eth1)10.10.10.11 rac1priv10.10.10.12 rac2priv # Public Virtual IP (VIP) addresses-(eth0)192.168.10.21 rac1vip192.168.10

1. What is audit?Audit (Audit) is used to monitor database operations performed by users, and Oracle stores audit trail resultsOS file(The default location is $ oracle_base/admin/$ oracle_sid/adump/) orDatabase(Stored in the system tablespaceSYS.

To put it simply, the blocks in oracle all have the identifier of an active transaction. If a transaction commit, because some blocks have been written back to datafile before the commit, or the number of Blocks Affected by the transaction is too

During the weekend, the RAC program was integrated in the nest, especially the VBOX software used in the notebook. Due to the unstable VBOX, the computer crashed and the graphical interface was not accessible. In this way, one node was dried

Some automatic conversion tools, including access export through odbc and csv import, were tried at the beginning of the migration, and some problems were found: for example, the field type conversion is not satisfactory, such as Boolean being

The maximum and minimum values of Histogram are oracle internal. The values queried by SQL select are encrypted. For example, all_tab_cols.low_value and all_tab_cols.high_value store the maximum and minimum values of a field in a table. However, if

Document directory Delete ---- truncate ---- drop Delete ---- truncate ---- drop Address: http://www.examw.com/Oracle/jishu/104237/ Delete (delete the statements recorded in the data table) Delete from table name where condition; Note: deleting a

Common oracle table partition usage: 1. table partitioning type: A) range Partition B) hash Partition C) List Partition D) composite partition includes range-Hash partition and list-Hash partition. 2. table partitioning syntax: syntax   A)