Distributed Database Architecture by liamei12345


									Oracle Architecture

A well-crafted architecture will also help you work more efficiently. The same is true for
databases. Despite the name “Oracle”, there is no magic!

The architecture that Oracle has built its database around is designed to perform quickly,
efficiently and without errors.

In this section we will introduce you to the Oracle architecture. This architecture includes the
following components:

* The System Global Area (SGA) and other memory areas that utilize RAM

* Database related background processes

* Tablespaces and Datafiles

* Database related files

* The instance and the database


 Scalability and Performance

          Concurrency
          Read Consistency
          Locking Mechanisms
          Quiesce Database
           RAC  Oracle Real Application Clusters (RAC) — an option for the Oracle
           Database software produced by Oracle Corporation and introduced in 2001 with Oracle9i —
           provides software for clustering and high availability in Oracle database environments
          Portability


          Self managing database
          OEM  Oracle Enterprise Manager (OEM or EM) aims to manage software produced
           by Oracle Corporation as well as by some non-Oracle entities.
          SQL*Plus
          ASM  Automatic Storage Management (ASM) is a new feature that has be introduced in
           Oracle 10g to simplify the storage of Oracle datafiles, controlfiles and logfiles.
          Scheduler
      Resource Manager

Backup and Recovery

High availability

Business Inteligence

      Data Warehousing
      ETL
      Materialized views
      Bitmap indexes
      Table compression
      Parallel Execution
      Analytic SQL
      OLAP
      Data mining
      Partitioning

Content Management

      XML
      LOB
      Oracle Text
      Oracle Ultra Search
      Oracle interMedia
      Oracle Spatial


Data integrity/Triggers

      Integrity constraints
      Triggers

Information Integration Features

      Distributes SQL
      Oracle Streams
          Database Replay                                           Partitioning

         Explore Database Replay, the new tool that                  Learn about Referential, Internal, and Virtual Column
captures SQL statements and lets you replay them at       partitioning; new sub-partitioning options; and more.

          Transaction Management                                    Schema Management

         Get an introduction to Flashback Data Archive                Add columns with a default value easily and explore
and explore Enterprise Manager's LogMiner interface.      invisible indexes, virtual columns, and read only tables.

          SQL Plan Management                                       SQL Performance Analyzer

           Use bind variables that pick the right plan             Accurately assess the impact of rewriting of SQL
every time and ensure a new execution plan is perfect     statements and get suggested improvements.
before it's used.

          SQL Access Advisor                                        PL/SQL: Efficient Coding

          Get advice about optimal table design based                 Triggers that fire several times at different events and
on actual use of the table, not just data.                ability to force triggers of the same type to follow a sequence
                                                          are some new gems.

          RMAN                                                      Security

          Explore Data Recovery Advisor, do parallel              Learn about Tablespace Encryption, case-sensitive
backup of the same file, and create and manage virtual    passwords, data masking, and other features.

          Automatic Storage Management                              Manageability

          Learn about new SYSASM role, variable                       Explore automatic memory management, multicolumn
extent sizes, and other ASM improvements.                 statistics, online patching, and more features.

          Caching and Pooling                                       SQL Operations: Pivot and Unpivot

         Explore SQL Result Cache, PL/SQL Function                  Present information in a spreadsheet-type crosstab
Cache, and Database Resident Connection Pooling.          report from any relational table using simple SQL, and store any
                                                          data from a crosstab table to a relational table.

          SecureFiles                                               Resiliency

          Explore next-generation LOBs: LOB                         Explore Automatic Health Monitor, Automatic
encryption, compression, deduplication, and               Diagnostic Repository, and other new resiliency features.

          Data Guard                                                PL/SQL Performance

          Query the physical standby database in real              Explore in-lining of code, "real" native compilation,
time without shutting down recovery, just for starters.   PLS timer, use of simple integer, and more.

          Data Warehousing and OLAP                                 And Don't Forget...

          Get a tour of new features in these areas,              COPY command, Export/Imports, Data Pump
including Cube Organized MVs.                             improvements, and more.
Distributed Database Architecture

A distributed database system allows applications to access data from local and
remote databases. In a homogenous distributed database system, each database
is an Oracle Database. In a heterogeneous distributed database system, at least
one of the databases is not an Oracle Database. Distributed databases use
a client/server architecture to process information requests.

This section contains the following topics:

      Homogenous Distributed Database Systems

       A homogenous distributed database system is a network of two or more Oracle
       Databases that reside on one or more machines.

      Heterogeneous Distributed Database Systems

       In a heterogeneous distributed database system, at least one of the databases is
       a non-Oracle Database system. To the application, the heterogeneous distributed
       database system appears as a single, local, Oracle Database. The local Oracle
       Database server hides the distribution and heterogeneity of the data.

      Client/Server Database Architecture

       A database server is the Oracle software managing a database, and a client is an
       application that requests information from a server. Each computer in a network
       is a node that can host one or more databases. Each node in a distributed
       database system can act as a client, a server, or both, depending on the

A Distributed database is a set of databases in a distributed system that can appear to
applications as a single data source.

Parallel execution is one of the fundamental database technologies that enable

organizations to manage and access terabytes of data. Without parallelism, these
large databases, commonly used for data warehouses but increasingly found in

operational systems as well, would not exist.

Simply defined, parallel execution is the ability to apply multiple CPU and IO

resources to the execution of a single database operation. While every major

database vendor today provides parallel capabilities, there remain key

differences in the architectures provided by the various vendors.

      Data concurrency means that many users can access data at the same time.
      Data consistency means that each user sees a consistent view of the data,
       including visible changes made by the user's own transactions and
       transactions of other users.

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