Identify two situations in which the block header grows in a data block. (Choose two.)
A.
When row directories need more row entries
B.
When there is row migration in the data block
C.
When there is an increase in the PCTFREE value for the data block
D.
When more transaction slots are required than are initially configured
block header
A part of a data block that includes information about the type of block, the address of the block, and sometimes transaction information.
data block
Smallest logical unit of data storage in Oracle Database. Other names for data blocks include Oracle blocks or pages. One data block corresponds to a specific number of bytes of physical space on disk.
Block header : block header contains the segment type ( such as table or index ) , data block address , table directory , row directory, and transaction slots. The size of each slot is approximately 23 bytes in the modified block rows will use these slots . Since the block header
The growth is carried out .
• Row data: This is the actual data block rows . Bottom- line growth in the data space .
• Free Space : free space in the middle of the block , and row data that allows head- space growth when necessary. When you insert a new row or update an existing row of columns with a larger value of the data row will occupy free space.
Example led to the growth include :
– Row entries need more lines
– Transaction requires more than the number of slots initially configured
Initially, the block of free space contiguous. However , delete, and update operations may cause the block of free space becomes fragmented. Oracle server when necessary engagement block of free space
What led to the growth of the event include:
– Row directory entries need more lines
– Transaction requires more than the number of slots initially configured
Block headed grows
PCTFREE – specify how much free space in a block for future UPDATE
BLOCK有長大,不是因為多了空閒空間(PCTFREE).
C is wrong