You executed the following command to create a tablespace called
SALES_DATA:
SQL> CREATE TABLESPACE sales_data DATAFILE SIZE 100M SEGMENT SPACE
MANAGEMENT AUTO;
Which two statements are true about the SALES_DATA tablespace? (Choose two.)
A.
The database automatically determines the extent-sizing policy for the tablespace.
B.
The segments are automatically shrunk when the contents are removed from them.
C.
The allocation of extents within the tablespace is managed through the dictionary tables.
D.
The space utilization description of the data blocks in segments is recorded in bitmap blocks.
E.
The space utilization description of the data blocks in segments is managed through free lists.
In a local tablespace, there are 2 methods that Oracle use to manage segment space: automatic and manual. Auto segment space management delivers better space utilization than manual segment space management. Although automatic segment space management is default for new permanent local tablespaces, you can explicitly enable it with the SEGMENT SPACE MANAGEMENT AUTO clause.
The units of database space allocation are data blocks, extents, and segments. When you create a table, Oracle allocates to the table’s data segment an initial extent of a specified number of data blocks. Oracle looks for free space to allocate to a new extent by first determining a candidate datafile in the tablespace and then searching the datafile’s bitmap for the required no of adjacent free blocks. If that datafile does not have enough adjacent free space, then Oracle looks in another datafile.
Every table has some free space. The free space is either BELOW the high water mark (the
point at which data has been inserted into the table) or ABOVE the HWM.
The free space BELOW the HWM is maintained in freelists. By default a segment has 1
freelist.
Free space can be managed automatically inside database segments. The in-segment free/used space is tracked using bitmaps, as opposed to free lists.
AUTO MGT – SIZE – BITMAP