Reading Notes: logical architecture of oracle

I. oracle logical architecture Diagram

Ii. Logical Structure

The logical structure of oralce includes:

1. tablespace

2. Segment

3. Zone

4. Block

The oracle database consists of several tablespaces. The tablespace consists of several segments, which are composed of several partitions.

Tablespaces are divided into system tablespaces, rollback segment tablespaces, temporary tablespaces, and user tablespaces.

The table we created corresponds to the segment in the logical structure. The T table is the T segment, but a table does not correspond to only one segment (if the table contains the lob field, then the lob field corresponds to at least two segments, one data segment and one index segment, or the table is a partition table, each partition corresponds to one segment)

The area is designed to avoid excessive expansion because the block size is too small. If the block size is expanded, the efficiency is too low;

The block is the minimum Logical Data Unit of oralce, And the partition is the minimum unit for oracle space allocation. The default size of the database block is 8 k, or other sizes, generally, it is an integer multiple of the OS block of the operating system.

Database block size

SQL> show parameter db_block_size;

NAME TYPE VALUE
----------------------------------------------------------------------------------------
Db_block_size integer 8192

Iv. Logical Structure of tablespaces

1. query common data table space, rollback segment tablespace, and system tablespace data files in the dba_data_files table.

2. query temporary tablespace data files in the dba_temp_files table

V. Logical Structure Zone

1. view the region information of a table