oracle024 Oracle's storage structure
storage structure-the storage structure of tablesTablespace: Consists of one or more files, and the spatial capacity of the tablespace is the sum of multiple file sizes
Tables and data files create a middle tier with many tables in the table space.
SELECT * from Dba_tablespaces;
System level:
System:orale's own information is the data dictionary, and the data dictionary table is placed in the system table space.
Sysaux: Is the system's satellite table space, and it is also the repository information
The above two table spaces must be online
UNDOTBS1: The location of the data block before the change
Temp: Temporary table space, used when temporary storage is needed, such as when the sort mentioned earlier, Sort_area space is insufficient
Users: User table space
Example: Sample table Space
But in actual production we can also create table spaces
Oracle is a multi-table space architecture that can be managed by dividing different table spaces and then dividing different data
Note: A tablespace contains one or more data files, and a data file belongs to only one table space
Assigning a segment the size is allocated in units of a region, with a series of contiguous blocks
A scheme (schema) is a user
SELECT * from Dba_segments;
One must belong to a user
Oracle Block
Oracle Block 8 bytes
Oracle Block physical storage Architecture
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Row Migration
file system block: dumpe2fs/dev/sda1 4 bytes
sector: 512 bytes
put more than one block under normal conditions.
pct Free: Indicates that a block is full when the remaining 10% of the data is inserted
Why do you do this? In order to avoid update when the data is increased, the data can not be modified
row migration: PCT free setup too small
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Oracle tries to put a row of data in one block
Oracle's storage structure
