Chapter8 Flashcards
facilitates the storage, modification and retrieval of this data.
Database Management System
the data consists of a set of relational objects.
relational database management system
Language used to interact with the Oracle
SQL
primary tool for an Oracle DBA
SQLPlus
web bases database management tool that is bundled with the Oracle
Enterprise Manager Database Control
Oracle server architecture can be described in three categories
User-related processes, Oracle instance, database
collection of logical memory structures
Oracle instance
Physical file structures
database
composed of the memory structures and background processes
instance
two type of process allow to user to interact with the instance and dabatase
User processes and server processes
process of initiating and maintaining communication between the user process and instance
connection
When the connection is made, the user establishes what?
session
it generally have a one-to-one relationship with user process
server process
Oracle’s main memory structure and shared memory area
System Global Area(SGA)
Required SGA components
Shared pool, Database buffer cache and redo log buffer
Caches the most recently used SQL statement that have been issued by the database users
Shared Pool
Caches the data that has been most recently accessed by the database users
Database buffer cache
Stores transaction information for recovery purposes
Redo log buffer
Memory in the SGA is allocated in units of contiguous memory called
granules
Three kinds of Database buffer cache
dirty buffers, free buffers, pinned buffers
buffer blocks that need to be written to the data files
Dirty buffers
do not cotain any data or are free to be overwritten
Free buffers
are the buffers that are currently being accessed or explicitly retained for future use.
Pinned buffers
Algorithm used to manage the contents of the shared pool and database buffer cache
Least Recently Used Algorithm
Writes the database blocks from the database buffer cache to the data files
Database Writer(DBWn)
A circular buffer in the SGA that holds information about the changes made to the database data.
Redo Log Buffer
changes made in the database are called
redo entries
writes the redo log information to other online redo log files
Log writer(LGWR)
Updates the data file headers following a checkpoint event
Checkpoint(CKPT)
Cleans up failed user database connections
Process Monitor
Performs instance recovery following an instance crash, coalesces free space in the database, and manages space used for sorting
System Monitor
An additional memory structure is also created for each user is called
Program Global Area(PGA)
Process that manages the size of each individual SGA components
Memory Manager
Process that gathers and analyzes statistics used by the Automatic Workload Repository feauture
Memory Monitor
Physical storage structures include three types of files
Control files, data files, redo log files
Information contained in this file are the locations of other physical files, database name, database block size, database character set, recovery information.
Control files
Information contained in this file are all application data and internal metadata
Data file
Information contained in this file are the record of all changes made to the database
Red log file
Main Database Architecture Components
Instance, Process, Storage, Memory
Database Instances:
Shutdown, NoMount, Mount, Open
Database instance where the instance started
NoMount
Database instance where the control file opened for this instance
Mount
Database instance where all files as describe by the control file for this instance
Open
Performs manageability-related background tasks
Memory Monitor(MMON)
Performs frequent and lightweight manageability-related tasks
Memory Monitor Light(MMNL)
Performs automatic memory management tasks
Memory Manager(MMAN)
Runs user jobs used in batch processing
Job Queue Coordinator(CJQ0)
Monitors the Streams Advanced Queuing message queues
AQ Coordinator(QMNC)
A data file can belong to one and only one tablespace. A tablespace could have more than one data file associated with it
true.
Smallest unit of storage in Oracle
Block
grouping of blocks
extent
it is a set of extents allocated for logical grouping
segment
Provides large memory allocations for:
- Session memory for the shared server and the Oracle XA interface
- I/O server processes
- Oracle Database backup and restore operations
Large pool
It started when a database user or a batch process connects to Oracle Database
User process
Connects to the Oracle instance and is started when a user establishes a session
Server Process
Are started when an Oracle instance is started
Database Processes
- It is used with distributed databases configuration
- Automatically connects to other databases involved in in-doubt distributed transactions
- Automatically resolves all in-doubt transactions
- Removes any rows that correspond to in-doubt trasactions
Recoverer Process
- Copy redo log files to a designated storage device after a log switch has occurred
- Can collect transaction redo data and transmit that data to standby destinations
Archiver Processes(ARCn)
a ____ is a set of database structures, such as tables, indexes, user-defined attributes.
Schema
