Database Administrator

Select count (1) from table use index (unique key ); Faster than using primary key indexes. I tested million production environment data, at least faster3Times .....   EXPLAINSELECT COUNT(1)From'Order'UseINDEX(PRIMARY) \ G; *

1. Create required data CREATE TABLE "TEST" ( "ID"NUMBERNOT NULLENABLE, "NAME"VARCHAR2 (50 BYTE)NOT NULLENABLE, "AGE"NUMBERNOT NULLENABLE, "DEPT"VARCHAR2 (50 BYTE)NOT NULLENABLE, CONSTRAINT "TEST_PK" PRIMARY KEY("ID") ENABLE ) XML

I. Transaction Concept Concept: transactions in databases are logical units of work. A transaction is composed of one or more SQL statements that complete a group of related behaviors, the transaction mechanism is used to ensure that the operations

1: Redis is a DSL tool for operating data structures. It provides TCP-based protocols to operate on rich data structures. 2: Redis is a memory database. It is precisely because of the fast access to memory that Redis can have such high performance.

Mysql multi-instance STARTUP script: #! /Bin/bash If ["$1" = ""] (enter the mysq port number to stop)ThenEcho "Please input mysqld GNR number 110-112" (this is the range of enabled port numbers) Elif (["$1 "! = "110"] & ["$1 "! = "111"] & ["$1 "!

Steps for upgrading Oracle from 10 Gb to 11 GBDatabaseOld Version: 10.2.0.4New database version: 11.2.0.2OS: Solaris 10Reference: Complete Checklist for Manual Upgrades to 11gR2 [ID 837570.1]Part 1-install 11gR2 SoftwareHereSoftwareOfInstallFor more

1. user_source Process Code of the current user2. user_objects contains all database objects owned by the user3. user_segments4. user_tables tablespace and tablespace Information5. user_tab_partitions partition information6. user_views7.

Recently, I have been playing with DG. Due to the shortage of disk resources, a policy for archiving logs is required. I found several scripts on the Internet and found that writing is so troublesome. Mao, So I simply wrote one, and the actual path

Background:Just a netizen asked the ORA-30009 error, the database version is 10.2.0.5, the operating system version is RedHat 4; then I took into account the hardware and buffer constraints, the verification, the details are as follows: Error

I. Performance adjustment objectives of Rodo Log: Among the many factors that can affect Oracle performance, Redo Log-related factors are, to some extent, the most important and most noteworthy. In an OLTP system, Oracle tries its best to complete

1. Create a table: Create table test (id int, name varchar (20), quarter int, profile int )) Insert into test values (1, 'A', 1,1000 );Insert into test values (1, 'A', 2,1000 );Insert into test values (1, 'A', 3,1000 );Insert into test values (1, 'A'

Tutorial 18: Table connection Query The purpose of this experiment is to master basic joint queries. Table join To obtain information from multiple tables, we can join the tables for query under certain conditions. Related reading: Basic query

Before executing an SQL statement, Oracle needs to first check the SQL Execution Plan and then execute the SQL statement according to the execution plan. The optimizer is responsible for analyzing the execution plan, under different conditions, an

Study mysql master-slave replication. During the Database Import and Export process, it is okay to export the master data, but the error mysqldump 1449 is returned when importing the master data from the database, then I searched for the solution on

The most important purpose of redo log files is to restore data (you can also use logminer). It records the database buffer cache (high-speed cache area) in the system global area (sga) all change information is recorded in the log buffer. However,

How to view the parameter of the Oracle database Method 1-show parameter SQL> show parameter NAMETYPE VALUE ----------------------- Background_core_dump stringPartial Background_dump_dest string D: \ ORACLE \ PRODUCT \ 10.2.0 \ ADMIN \

Here we use a project integrating mongodb in spring-data. First, add the dependency on it in maven. Here we use version 1.0.0.M5. Dependency> GroupId>Org. springframework. dataGroupId> ArtifactId>Spring-data-mongodbArtifactId> Version>1.0.0.M5

Install MySQL 5.5 in CentOS 1. Install cmake# Install the required dependency packageYum-y install gcc libxml2-dev curl screen \Libpng12-dev autoconf libpcre3-dev make bzip2 \Libevent-dev patch libjpeg62-dev libcurl4-openssl-dev \Libfreetype6-dev g +

After watching the struts video, I started learning about Hibernate. After writing a few examples, I found that this framework is really convenient and easy to use. Its advantages and disadvantages: 1. A special advantage of Hibernate is to simplify

Differences between Oracle row triggering and statement triggering 1. the row trigger has a for each row clause. The statement trigger does not have a for each row clause.2. the row trigger can have the when as the trigger limit. You can use new/old.