Part II describes the basic structural architecture of the Oracle database, including physical and logical storage structures. Part II contains the following chapters. Here is a brief explanation of architecture: Oracle Server architecture | | |– Oracle Instance (SGA + Background Process) | | | |– SGA (System. ORACLE SERVER can be on a whole divided in two broad layers: LOGICAL LAYER PHYSICAL LAYER LOGICAL LAYER: Any application whenever needs to.


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These segments are used during various database operations, such as sorts. Oracle 10g architecture Extents are the building blocks of segments; in turn, they consist of data blocks.

An extent is used to minimize the amount of wasted empty storage.

As more and more data is entered into tablespaces in your database, the extents used to store that data can grow or shrink as necessary. In this manner, many tablespaces can share the same storage space without preallocating the divisions between those tablespaces.

At tablespace-creation time, you can specify the minimum number of extents to allocate as well as the number of extents to add at a oracle 10g architecture when that allocation has been used.

This arrangement gives you efficient control over the space used in your database. Data Blocks Data blocks are the smallest pieces of an Oracle database; they are physically stored on disk.

Although the data block in most systems is oracle 10g architecture 2, bytesyou can change this size for efficiency depending on your application or operating system.

Oracle Database 10g: Architecture for Developers Training

Segments An Oracle database can use four types of segments: The Oracle Instance The Oracle instance consists of the Oracle processes and shared memory necessary to access information in the database. The instance is made oracle 10g architecture of the user processes, the Oracle background processes, and the shared memory used by these processes see Figure Below.

Oracle uses shared memory for several purposes, including caching of data and indexes as well as storing shared program code. This shared memory is broken into various pieces, or memory structures. The SGA is allocated when the Oracle instance starts and deallocated when the Oracle instance shuts down.

10g Architecture | Oracle DBA solutions

Each Oracle instance that starts has its own SGA. The information in the SGA consists of the following elements, each of which has a oracle 10g architecture size and is created at instance startup: The database buffer cache--This stores the most recently used data blocks.

These blocks can contain modified data that has not yet been written to disk sometimes oracle 10g architecture as dirty blocksblocks that have not been modified, or blocks that have been written to disk since modification sometimes known as clean blocks.

The redo log buffer--This stores redo entries, or a log of changes made to the database.

10g Architecture

The redo log buffers are written to the redo log as quickly and efficiently as possible. Remember that the redo oracle 10g architecture is used for instance recovery oracle 10g architecture the event of a system failure.

The shared pool--This is the area of the SGA that stores shared memory structures such as shared SQL areas in the library cache and internal information in the data dictionary. The shared pool is important because an insufficient amount of memory allocated to the shared pool can cause performance degradation.

Oracle 10g architecture diagram: | Database Worksheets

Oracle 10g architecture shared pool consists of the library cache and the data-dictionary cache. Here the parse tree and the execution plan for every unique SQL statement are cached.


If multiple applications issue the same SQL statement, the shared SQL area can be accessed by each to oracle 10g architecture the amount of memory needed and to reduce the processing time used for parsing and execution planning.

The Data-Dictionary Cache The data dictionary contains a oracle 10g architecture of tables and views that Oracle uses as a reference to the database.

Oracle Database Architecture

Then the database is opened then comes the roll back phase where all the uncommited transaction are rolled back and then the files are brought in a consistent mode. It is responsible in releasing the resources and locks in case of abnormal termination of user processes.

These were the five mandatory background processes which are taken up in the architecture oracle 10g architecture Oracle 10g.