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You can declare intermediate markers called savepoints within the context of atransaction. Savepoints divide a long transaction into smaller parts.Using savepoints, you can arbitrarily mark your work at any point within a longtransaction. You then have the option later of rolling back work performedbefore the current point in the transaction but after a declared savepoint within the transaction. For example, you can use savepoints throughout a long complex series of updates,soif you make an erro

摘自myourBSP : blog service provider，博客（托管）服务提供商。意思是公司或者非营利组织为单个人或者其他组织免费或者有偿提供blog服务，blog服务包括空间、 blog程序、blog服务维护等。国内有博客中国、blogcn、blogdriver、blogbus等，国外有blogger、typepad等。为什么会有bsp的产生？首先，确实有一大批人想使用blog服务，而不会自己架设服务器和程序，或者因为各种原因，总之自己不可以做bsp说做的事情，所以需要bsp；而bsp因为可以获得用户所产生的流量，及相应的广告位资源，进而获得相应的收益和投资，所以bsp也原因给这些用户

摘自sparkweaverlilina is a simple but powerful news aggregator written in PHP. No database is needed, RSS/ATOM parsing is done by the excelent MagpieRSS library (it is included, no additional installation needed). It features feed auto-discovery and an easy-to-use interface.lilina是一个小而实用的新闻聚合器，越来越多的朋友喜欢把lilina放到自己的博客上，这样可以在自己的网站上与朋友分享知识的同时也很方便地阅读自己订阅的一些博客。lilina目前是一个独立的应用程序.[@more@]

摘自monn-soft传统的网络服务程序，如：ftp、pop和telnet在本质上都是不安全的，因为它们在网络上用明文传送口令和数据，别有用心的人非常容易就可以截获这些口令和数据。而且，这些服务程序的安全验证方式也是有其弱点的，就是很容易受到“中间人”（man-in-the-middle）这种方式的攻击。所谓 “中间人”的攻击方式，就是“中间人”冒充真正的服务器接收你的传给服务器的数据，然后再冒充你把数据传给真正的服务器。服务器和你之间的数据传送被“中间人”一转手做了手脚之后，就会出现很严重的问题。 SSH的英文全称是Secure SHell。通过使

Rolling back means undoing any changes to data that have been performed by SQLstatements within an uncommitted transaction. Oracle uses undo tablespaces (orrollback segments) to store old values. The redo log contains a record of changes.Oracle lets you roll back an entire uncommitted transaction. Alternatively, you can rollback the trailing portion of an uncommitted transaction to a marker called a savepoint.All types of rollbacks use the same procedures:■ Statement-level rollback (due to stat

Committing a transaction means making permanent the changes performed by theSQL statements within the transaction.Before a transaction that modifies data is committed, the following has occurred:■ Oracle has generated undo information. The undo information contains the olddata values changed by the SQL statements of the transaction.■ Oracle has generated redo log entries in the redo log buffer of the SGA. The redolog record contains the change to the data block and the change to the rollbackbl

A transaction in Oracle begins when the first executable SQL statement is encountered.An executable SQL statement is a SQL statement that generates calls to an instance,including DML and DDL statements.When a transaction begins, Oracle assigns the transaction to an available undotablespace to record the rollback entries for the new transaction.A transaction ends when any of the following occurs:■ A user issues a COMMIT or ROLLBACK statement without a SAVEPOINT clause.■ A user runs a DDL statem

Oracle provides a means for suspending, and later resuming, the execution of largedatabase operations in the event of space allocation failures. This enables anadministrator to take corrective action, instead of the Oracle database server returningan error to the user. After the error condition is corrected, the suspended operationautomatically resumes.A statement runs in a resumable mode only when the client explicitly enablesresumable semantics for the session using the ALTER SESSION statement

If at any time during execution a SQL statement causes an error, all effects of the statement are rolled back. The effect of the rollback is as if that statement had never been run. This operation is a statement-level rollback.Errors discovered during SQL statement execution cause statement-level rollbacks. An example of such an error is attempting to insert a duplicate value in a primary key. Single SQL statements involved in a deadlock (competition for the same data) can also cause a statement

A SQL statement that runs successfully is different from a committed transaction. Executing successfully means that a single statement was: ■ Parsed ■ Found to be a valid SQL construction■ Run without error as an atomic unit. For example, all rows of a multirow update are changed. However, until the transaction that contains the statement is committed, the transaction can be rolled back, and all of the changes of the statement can be undone. A statement, rather than a transaction, runs succes

A transaction is a logical unit of work that contains one or more SQL statements. Atransaction is an atomic unit. The effects of all the SQL statements in a transaction canbe either all committed (applied to the database) or all rolled back (undone from thedatabase).A transaction begins with the first executable SQL statement. A transaction ends whenit is committed or rolled back, either explicitly with a COMMIT or ROLLBACK statementor implicitly when a DDL statement is issued.事务简介1. 包含

SNS:Social Network Sofwaret，社会性网络软件，依据六度理论，以认识朋友的朋友为基础，扩展自己的人脉。并且无限扩张自己的人脉，在需要的时候，可以随时获取一点，得到该人脉的帮助。　　SNS网站，就是依据六度理论建立的网站，帮你运营朋友圈的朋友。　　六度关系理论:美国著名社会心理学家米尔格伦(Stanley Milgram)于20世纪60年代最先提出，在人际脉络中，要结识任何一位陌生的朋友，这中间最多只要通过六个朋友就能达到目的。就是说你想认识一个人，托朋友找朋友找认识他的人，之间不会超过六个人。[@more@]

The lowest-level software connecting the user side to the Oracle side of the programinterface is the communications software, which is provided by the host operatingsystem. DECnet, TCP/IP, LU6.2, and ASYNC are examples. The communicationsoftware can be supplied by Oracle, but it is usually purchased separately from thehardware vendor or a third-party software supplier.操作系统的通信传输软件通信传输软件是用户侧连往Oracle侧最底层的程序接口软件[@more@]

Drivers are pieces of software that transport data, usually across a network. Theyperform operations such as connect, disconnect, signal errors, and test for errors.Drivers are specific to a communications protocol, and there is always a default driver.You can install multiple drivers (such as the asynchronous or DECnet drivers) andselect one as the default driver, but allow an individual user to use other drivers byspecifying the desired driver at the time of connection. Different processes can

The program interface consists of the following pieces:■ Oracle call interface (OCI) or the Oracle runtime library (SQLLIB)■ The client or user side of the program interface (also called the UPI)■ Various Oracle Net Services drivers (protocol-specific communications software)■ Operating system communications software■ The server or Oracle side of the program interface (also called the OPI)Both the user and Oracle sides of the program interface run Oracle software, as do thedrivers.Oracle Ne

The program interface is the software layer between a database application andOracle. The program interface:■ Provides a security barrier, preventing destructive access to the SGA by client userprocesses■ Acts as a communication mechanism, formatting information requests, passingdata, and trapping and returning errors■ Converts and translates data, particularly between different types of computers orto external user program datatypesThe Oracle code acts as a server, performing database tasks

The user and server processes are separate, distinct processes. The separate serverprocess created on behalf of each user process is called a dedicated server process (orshadow process), because this server process acts only on behalf of the associated userprocess.This configuration maintains a one-to-one ratio between the number of user processesand server processes. Even when the user is not actively making a database request,the dedicated server process remains (though it is inactive and can

top命令和ps命令的基本作用是相同的，显示系统当前的进程和其它状况；但是top是一个动态显示过程，即可以通过用户按键来不断刷新当前状态。如? 前台执行该命令，它将独占前台，直到用户终止该程序为止。比较准确的说，top命令提供了实时的对系统处理器的状态监视。它将显示系统中CPU最“敏感”的任务列表。该命令可以按CPU使用、内存使用、执行时间对任务进行排序；而且该命令的很多特性都可以通过交互式命令或者在个人定制文件中进行设定。在后面的介绍中将把命令参数和交互命令分开讲述。top命令语法：top [-] [d delay] [q] [c] [s] [S

Certain administrative activities cannot be performed while connected to a dispatcherprocess, including shutting down or starting an instance and media recovery. An errormessage is issued if you attempt to perform these activities while connected to adispatcher process.These activities are typically performed when connected with administrator privileges.When you want to connect with administrator privileges in a system configured withshared servers, you must state in your connect string that you

Each shared server process serves multiple client requests in the shared serverconfiguration. Shared server processes and dedicated server processes provide thesame functionality, except shared server processes are not associated with a specificuser process. Instead, a shared server process serves any client request in the sharedserver configuration.The PGA of a shared server process does not contain user-related data (which needs tobe accessible to all shared server processes). The PGA of a sha