MySQL\Oracle\Informix\MS SQL\BDB\Sqlite\NoSQL etc

mysqld_multi 配置MySQL多实例



wget -c ftp://ftp.mirrorservice.org/sites/ftp.mysql.com/Downloads/MySQL-5.1/mysql-5.1.60.tar.gz


MySQL Cluster fault tolerance – impact of deployment decisions

MySQL Cluster fault tolerance – impact of deployment decisions

Typical management configuration

Fig 1. Typical management configuration

MySQL Cluster is designed to be a High Availability, Fault Tolerant database where no single failure results in any loss of service.

This is however dependent on how the user chooses to architect the configuration – in terms of which nodes are placed on which physical hosts, and which physical resources each physical host is dependent on (for example if the two blades containing the data nodes making up a particular node group are cooled by the same fan then the failure of that fan could result in the loss of the whole database).

Of course, there’s always the possibility of an entire data center being lost due to earthquake, sabotage etc. and so for a fully available system, you should consider using asynchronous replication to a geographically remote Cluster.

Fig 1. illustrates a typical small configuration with one or more data nodes from different node groups being stored on two different physical hosts and a management node on an independent machines (probably co-located with other applications as its resource requirements are minimal. If any single node (process) or physical host is lost then service can continue.


不同场景下 MySQL 的迁移方案

一 目录

二 为什么要迁移


Configuring MySQL Master-Master Replication

MySQL Master-Master replication adds speed and redundancy for active websites. With replication, two separate MySQL servers act as a cluster. Database clustering is particularly useful for high availability website configurations. Use two separate Linodes to configure database replication, each with private IPv4 addresses.

This guide is written for a non-root user. Commands that require elevated privileges are prefixed with sudo. If you’re not familiar with the sudo command, you can check our Users and Groups guide.

This guide is written for Debian 7 or Ubuntu 14.04.

Install MySQL


使用 Informix Dynamic Server 的复制技术


IBM® Informix® Dynamic Server(IDS)一直以来都是一种具备强大复制技术的数据库。企业复制(Enterprise Replication,ER)和高可用性数据复制(High-Availability Data Replication,HDR)多年来为客户提供了可靠的服务。在较新的 IDS 版本 11.1 以及目前的 11.5 中,又添加了一些新的技术:远程独立(Remote Standalone)备用服务器和共享磁盘(Shared-Disk)备用服务器。本文将通过使用这些技术来简要了解各种技术的特征和细节。

通过 oncheck 理解 Informix 索引结构

通过 oncheck 理解 Informix 索引结构

在 Informix 数据库中,索引对数据库的性能有着重大的影响。本文通过 oncheck 命令来展示实际的 Informix 索引结构,使读者对 Informix 索引的层次、根节点、分支节点、叶节点等有较深的理解,明白“单列索引和多列索引”、“唯一索引和非唯一索引”在内部结构上的区别。读者理解 Informix 索引结构后,可以更好的设计 Informix 索引,较大的提升 Informix 数据库和 Informix 应用程序的性能。


在 Informix 中,可以通过索引来快速定位“需要使用的数据行”。那么一般的 Informix 索引是通过什么结构来实现“快速定位数据行”的目的呢?本文将通过 oncheck 命令来展示实际的 Informix 索引结构,为您揭晓这个问题的答案。 继续阅读



要登录到 Microsoft SQL Server 的实例,主体必须有一个有效的 SQL Server 登录名。 在身份验证过程中会使用此登录名,以验证是否允许主体连接到该 SQL Server 实例。 可在 sys.server_principals 目录视图和 sys.syslogins 兼容性视图中查看服务器实例上的 SQL Server 登录名。

SQL Server 登录名使用映射到 SQL Server 登录名的数据库用户访问各个数据库。 此规则有两种例外情况:

  • guest 帐户。 这个帐户在数据库中启用后,能够使未映射到数据库用户的 SQL Server 登录名作为 guest 用户进入数据库。
  • Microsoft Windows 组成员身份。 如果某 Windows 用户是 Windows 组的成员,并且此组也是数据库中的用户,则基于该 Windows 用户创建的 SQL Server 登录名可以进入数据库。

有关 SQL Server 登录名与数据库用户的映射关系的信息存储在数据库中。 其中包括数据库用户的名称以及对应 SQL Server 登录名的 SID。 该数据库用户的权限用于在数据库中进行授权。 继续阅读

如何在 SQL Server 2005 实例之间传输登录和密码

本文介绍如何在不同服务器上的 Microsoft SQL Server 2005 实例之间传输登录和密码。

有关如何在其他版本的 SQL Server 实例之间传输登录和密码的更多信息,请单击下面的文章编号,以查看 Microsoft 知识库中相应的文章:

246133 如何在 SQL Server 实例之间传输登录和密码


onunload and onload

The onunload functionality of the application is a database or table written to tape, the program in binary form to the disk page as a unit to remove the data, the data unloaded in this way the efficiency of higher than dbexport.
Read to use onload applications created by onunload tape. The machine receiving data and create a tape machine must have the same page size.
Only users with database DBA privileges to remove the database. Only the owner of the table or the table where the database user with DBA privileges can remove the table.
Remove the table, only the data and index pages associated with the table is removed. Defined for the table access permissions and synonyms related to the table or view is not unloaded onto the tape.
Remove the operation during onunload exclusive way to block new database or table.

onunload 应用程序的功能是将数据库或表写到磁带上,该程序以二进制形式,以磁盘页为单位卸下数据,这种方式卸下的数据其效率高于dbexport。