Oracle Storage Structure and oracle Storage Structure

Oracle Storage Structure and oracle Storage Structure
Oracle Storage Structure
Storage Structure-Table Storage StructureTable space: A table space is composed of one or more files. The space capacity of a table space is the total size of multiple files.
Create an intermediate layer between a table and a data file. There are many tables in the tablespace.

Select * from DBA_TABLESPACES;
System Level:
SYSTEM: the information of orale itself is the data dictionary. The data dictionary table is placed in the system tablespace.
Sysaux: refers to the tablespace attached to the system and stores system information.
// The preceding two tablespaces must be online.
UNDOTBS1: Change the storage location of the previous data block
TEMP: Temporary tablespace, used when temporary storage is required. For example, in sorting as mentioned earlier, when sort_area space is insufficient

Users: User tablespace
Example: example tablespace

However, in actual production, we can also create tablespaces.

Oracle is a multi-tablespace architecture, which is managed by dividing different tablespaces and then dividing different data.
Note: a tablespace contains one or more data files, and a data file only belongs to a tablespace.
The size of a segment is allocated in the unit of zone. A zone consists of a series of consecutive blocks.

A schema is a user.
Select * from DBA_SEGMENTS;
A user must belong to one user.




Oracle Block
Oracle block 8 bytes
Oracle block physical storage structure
Line Link
Row migration
File System block: dumpe2fs/dev/sda1 4 bytes
Sector: 512 bytes

Normally, multiple rows are placed in the next block.

Pct free: indicates that when 10% of data is inserted to a block, the block is deemed to be full.
Why? To avoid data addition during update, the data cannot be modified.

Row migration: the pct free setting is too small.
Line link:
Oracle tries its best to put a row of data in a block