Database Administrator

Cannot set user id: Resource temporarily unavailable A while ago, Infra reported that the database server could not be connected through putty and SecureCRT. The error message is Resource temporarily unavailable. Since there are almost 20 nstance on

Oracle multi-key partition Test Partitions can be partitioned by two fields. The first column is compared first. If yes, the second column is ignored. If the first column is not met, the second column needs to be compared. This partitioning method

MySQL changes the password and forgets the ROOT password This document introduces how to modify the user password of MYSQL and how to handle the problem after the root password is forgotten. I. Three password modification methods 1. Modify the logon

Summary of MySQL paging technology -- Method 1: directly use the SQL statements provided by the database--- Statement style: MySQL can use the following method: SELECT * FROM table name limit m, N--- Applicable scenario: Suitable for scenarios with

ORA-12519, TNS: no appropriate service handler found Sometimes it can be connected to the Oracle database, and sometimes it cannot be connected. It may be that the current number of connections on the Oracle database has exceeded the maximum

Summary of MySQL performance monitoring methods --- First, the concept that logical reads in Oracle correspond to physical reads is to count and classify the number of data accesses using the data cache technology.--- Physical read, which actually

Install MySQL 5.5 using CMake This article introduces how to install MYSQL 5.5.36 database through rpm. I. Environment Description OS: Oracle LINUX SERVER _ 64 6.3 software source code package storage location/usr/local/src Source code package

The display of MySQL execution plan does not match the execution process The process of creating a table and phenomena is as follows: Create table t1 (id1 INT, a1 INT, b1 INT, primary key (id1 ));Create table t3 (id3 int unique, a3 INT, b3 INT

Instance recovery and Oracle SCN, instance oraclescn A simple understanding of oracle's SCN is its own time function, just like the linux system's own time, oracle also has its own set of time. When you close the database cleanly, shutdown immediate

Summary of keywords of database query statements, and Keywords of database statementsAfter reading the niuyun video, I wrote the background code in the first 17 episodes, especially when talking about query statements. I suddenly felt that the

Four SQL languages: DDL, DML, DCL, TCL, and dmldcl1. DDL (Data Definition Language) Database Definition Language statements are used to define the database structure or schema. Defines the three-level structure of the database, including the

Chapter 2 User Authentication, Authorization, and Security (9): prevents login names and users from viewing metadata, authenticationSource: Workshop Without the consent of the author, no one shall be published in the form of "original" or used for

Tracking the SQL statement execution process and related knowledge development in oracle, oraclesql select * from v$sqlarea; select * from v$sqlarea where first_load_time>'2010-11-27/09:30:00';Each record in the query result of this method displays

The procedure of the test interview (Database concept knowledge) and the test interview Section 1: Related Concepts: 1> Data: Data is the basic object stored in the database and a symbolic record describing a transaction. 2> DataBase: a DataBase is

Oracle cluster heartbeat and Its Parameter misscount/disktimeout/reboottime, oracle Cluster In Oracle RAC, you can check the health status of RAC from multiple levels and different mechanisms, that is, you can isolate faults through the heartbeat

In the xxMapper. xml file of mybaits, the numbers are greater than the numbers and smaller than the numbers.Method 1: Because it is in xml format, it is not allowed to contain characters such as ">", but both can be used symbols are described, so

QlikView calculates the sales data from the beginning of the year to today. The sum of sales from the beginning of the new fiscal year to today is a common demand of many students. There are two ideas: 1. You can generate a field named YTDFlag when

PHP converts the database content to a csv file, PHP converts the database content into csv files separated by commas (,). To prevent the contents of the database from containing commas (,) and affect file content display, add "" (double quotation

Oracle initialization or shutdown in progress solution, oracleshutdown I encountered an error message "oracle initialization or shutdown in SS" when logging on to oracle today. I searched the internet and tried many methods. Finally, I combined

Oracle merge into... USING two table join operations (high efficiency), mergeinto... using When the data volume is small, you can use subqueries to associate two tables. However, when the data volume is large, the subquery efficiency is too low