Therefore, you can see the advantages of using
ASM: You can easily add another disk volume to the disk group where the datafile resides, and
Oracle will automatically redistribute the contents of the datafile and allow the tablespace to
grow??”all of this occurring while the database (and the tablespace itself) is available to users.
By default, tablespaces are created as smallfile tablespaces; you can specify the default tablespace
type when the database is created or at any time with the alter database command, as in this example:
SQL> alter database set default bigfile tablespace;
Database altered.
Bigfile Tablespace ROWID Format
To facilitate the larger address space for bigfile tablespaces, a new extended ROWID format is
used for rows of tables in bigfile tablespaces. First, we will review the ROWID format for smallfile
tablespaces in previous versions of Oracle and for Oracle 11g. The format for a smallfile ROWID
consists of four parts:
OOOOOO FFF BBBBBB RRR
Tablespace Block Size Maximum Smallfile Datafile Size Maximum Bigfile Datafile Size
2K 8GB 8TB
4K 16GB 16TB
8K 32GB 32TB
16K 64GB 64TB
32K 128GB 128TB
TABLE 16-1 Maximum Tablespace Datafile Sizes
Chapter 16: Managing Large Databases 547
Table 16-2 defines each part of a smallfile ROWID.
In contrast, a bigfile tablespace only has one datafile, and its relative datafile number is always
1024. Because the relative datafile number is fixed, it is not needed as part of the ROWID; as a
result, the part of the ROWID used for the relative datafile number can be used to expand the size
of the block number field.
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