Oracle Advanced Notes-Administrator 1-Database logical Structure

-------------------------------Logical Structure------------------------------------

Reference Document: Chapter 12

Tablespace table Space Maximum storage unit Establishment object specifies that the table space is stored

Segment segment: Can store data table segment (set up table XS must suggest segment XS)

Extent Area: Space allocation unit (at least one area of the object)

Oracle data Block database blocks minimum i/0 units

Contiguous data blocks store the same type of data region as a segment in a single table space only one table space in a single database

For example: I set up a table xs (ID number, name char (10)) to specify that the Tablespace insert 1 data for users

CREATE TABLE Scott.xs (ID number, name char (TEN)) tablespace users;

INSERT into SCOTT.XS values (1, ' Tom ');

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Commit

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The data that is inserted into the XS segment is allocated in the Users table space

How much space is allocated to the XS segment, if I continue to insert data, the segment will be full and continue to allocate space in extent units

Select Segment_name,segment_type, tablespace_name,extent_id, BLOCKS

From Dba_extents

where OWNER = ' SCOTT ' and segment_name= ' XS ';

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Segment name XS

is a table segment

Using space is the users

extent_id First District is 0 (numbering starting from 0)

Blocks occupies 8 blocks

What is the size of a block?

Sql> Show Parameter Db_block_size

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Summary: I set up a segment XS using the uses table space, allocating 1 zones to occupy 8 blocks total size of 64K

Continue inserting, what if the amount of data is larger than the 64K database?

INSERT INTO SCOTT.XS select * from Scott.xs;

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Sql> Select Segment_name,segment_type, tablespace_name,extent_id, BLOCKS

From Dba_extents

where OWNER = ' SCOTT ' and segment_name= ' XS ';

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Area is a contiguous block of data

block_id Start number

Select Segment_name,segment_type, tablespace_name,extent_id, block_id,blocks

From Dba_extents

where OWNER = ' SCOTT ' and segment_name= ' XS ';

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Tablespaces and data files table space relationships

Table spaces are divided into large file tablespaces: Only 1 data files in a tablespace can be supported to 128T (?).

Small file Tablespace (default): There can be multiple data files in a table space

System and Sysaux are forced by default when building a library

System must be online, storage is core function (data dictionary)

Sysaux Information for storing EM

System Sysaux does not recommend storing user data

Summarize:

1 Oracle Server =instance +database

2 instance =meomoy +process

3 Physical Structure

4 Logical Structure