Database Administrator

ONS (Oracle notification service) ONS--A publish and subscribe service for communicating Fast Application Notification (FAN) events. Mainly used for connecting middleware and databases. Ps-ef | grep onsCrs_stat-t Name Type Target State Host ---------

When performing the MERGE operation, how do I obtain the number of updated rows and the number of inserted rows? First, create a test table as follows:Create table emp_sourceSELECT * FROM emp; -- 14 rows Create table emp_targetSELECT * FROM

Oracle 11g (11.2.0.1.0) has a bug. When the table has no data, no segment is assigned. Solution: 1. insert a row and then roll back to generate a segment. This method inserts data into an empty table and then deletes it, resulting in a segment. An

#! /Bin/bash# Function:# Backup user_data# History:# Copyright @ 2011 zhaohaihuaExport extfile = 'date' + % Y % m % d % H % m''Export bak_dir =/home/Oracle/data_bakSu-oracle-c "exp user01/user01 file = $ bak_dir/user01. $ extfile. dmp compress = y

-- Oracle PagingDefined cursor Create or replace package chj1_packageType chjiw.cursor is ref cursor;End chj1_package; -- StepSelect t1. *, rownum from (select * from chengji) t1-- Step 2Select t1. *, rownum rn from (select * from chengji) t1 where

When I first came into contact with SQL Server, I thought that SQL Server would update statistics while changing data. In fact, SQL Server did not. based on performance considerations, SQL Server uses the following algorithm to update

After I restored the Deleted Data Based on scn last time, I felt that I should have a good understanding of the scn. Today I found some related introductions on the Internet and referred to some articles, here I will summarize the experiment. After

MySQL string truncation functions: left (), right (), substring (), substring_index (). There are also mid () and substr (). Here, mid () and substr () are equivalent to substring () functions. substring () functions are very powerful and flexible. 1

The group by Statement supports basic having conditions and provides information aggregation functions for rollup and cube, similar to subtotal. Rollup: vertical subtotal, which summarizes each column one by one from right to left and generates an

Today, when the company changed tomcat, the connection to the database failed. In the beginning, the password expired. Later, the password was changed from Oracle. When trying to connect, an error was reported that the password was locked, check the

I always thought that except rollup and cube, group by can be aggregated at different granularities according to the fields specified in the clause. There are no other methods. Today, another method is found because of the groupby bug (hash group B

Mmgr is the memory management module of postgresql. Its code is distributed in three files: aset. c, mctx. c, and portalmem. c. Here we mainly analyze its heap memory management mechanism, that is, the content in the aset. c file. AllocSetContext is

1. Description of mysql_install_dbWhen the MySQL System Database (mysql System Database) fails or a new mysql instance needs to be added, You need to initialize the mysql

As a test, in order to eliminate the impact of the cache, it is clear that the cache is a common thing, so the command to clear the cache must still be remembered. below is the FLUSH parameter of my mobile phone from other websites. Flush_option can

Modifying the DATABASE spfile file in Oracle 11GR2 RAC is not the original $ ORACLE_HOME/dbs/init . ora file. If we manually modify this file, it will still take effect when SQL plus is used to manually start the database, but if we use srvctl or

The front-end can select multiple different conditions under the same field, which involves the problem of SQL statement concatenation. The following is a method for processing query conditions using regular expressions. It is the simplest method I

Install postgresql on openSUSE and record the steps below. Read more: Install Mono on openSUSE and release ASP. Net programs Environment I tested the installation of postgresql 8.4.6 on openSUSE 11.3, and the installation of postgresql 9.0.3 on

SQL Server provides the sp_monitor stored procedure for you to view SQL Server performance statistics, including CPU, Network, and IO. With this information, you can have a general understanding of your database performance. The following example

An Oracle error message ORA-28001: the password has expired was reported when an alert was received that the monitored user could not connect to the database. the script for getting the user's basic information was as follows: Connect/as sysdba; Col

An error occurred while connecting to the database using rman today.[Bkjia @ rhel55 ~] $ Rman target sys/Oracle @ orcl ORA-12514: TNS: listener does not currently know of service requested in connect descriptor[Bkjia @ rhel55 ~] $ Lsnrctl