Oracle 9i Database Administration in 10 Minutes
CH1: Understanding the Oracle Environment | CH2: Understanding the Oracle Instance | CH3: Understanding the working of Oracle Instance | CH4: Understanding Oracle Database | CH5: Oracle 9i Software Installation | CH6: Oracle 9i Database Design using DBCA | CH7: Enabling Other Computers to Access Oracle Server | CH8: Oracle Enterprise Manger | CH9: Oracle Backup & Recovery -Simple Technique | CH10: Oracle Performance Tuning
Chapter 4: Understanding Oracle Database
Logical Architecture:
Logically the data inside the database resides inside the tablespaces.
Each tablespace is comprised of segments. Oracle Instance allocates a
segment each time you create a object (table, view etc) inside the
database. Each segment is composed of Extents and What are Extents? Each
extent is a group of contiguous DB Blocks. Now what are DB Blocks? A DB
Block is the smallest building block of the database and is usually the
even multiple of OS Block e.g. DB Block can be (2 * OS Block) but not
(1.37 * OS Block). The size of the DB Block can be specified using
DB_BLOCK_SIZE init.ora parameter. You can assign values like 2KB (2 Kilo
Byes) and if the OS permits you can have 4KB, 8KB etc.
Figure 11: Oracle database logical architecture.
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Chapter 4: Understanding Oracle Database
CH1: Understanding the Oracle Environment | CH2: Understanding the Oracle Instance | CH3: Understanding the working of Oracle Instance | CH4: Understanding Oracle Database | CH5: Oracle 9i Software Installation | CH6: Oracle 9i Database Design using DBCA | CH7: Enabling Other Computers to Access Oracle Server | CH8: Oracle Enterprise Manger | CH9: Oracle Backup & Recovery -Simple Technique | CH10: Oracle Performance Tuning