Databases Reference
In-Depth Information
c.
Specify quotas as necessary for the Oracle schemas that will need to store data on the
DBFS file system
d.
Create external tables and specify an appropriate degree of parallelism for segments
using this DBFS data store as appropriate
Listing 21-6 will show how to create an Oracle directory on this
DBFS
file system and grant permissions so that an
APPS
schema can access the directory with unlimited quotas:
Listing 21-6.
lst21-06-dbfs-dir-perm.sql
SQL> create directory dbfs_dir
as '/data_dbfs/DATA_DBFS'
/
Directory created.
SQL> grant all on directory dbfs_dir to apps
/
Grant succeeded.
SQL> alter user apps quota unlimited on dbfs_tbs
/
User altered.
SQL>
How It Works
Oracle's Database File System on Exadata functions as it does on non-Exadata 11gR2 Oracle installations. With Oracle
Exadata, use of
DBFS
is widely recognized as a very fast mechanism to load data into your database from external files,
and as such, is used in many Oracle migrations to Exadata
DBFS
for performance reasons.
At its core, DBFS uses storage defined inside the database and externalizes this to operating system file systems.
Its roots are with Oracle iFS (Internet File System), but its functionality and capabilities have been extended with
Oracle 11gR2. Some of the reasons why
DBFS
can be an excellent fit in your Exadata environment include the
following:
DBFS
files can be parallelized using parallel query for optimal performance.
•
Operations against
DBFS
file systems, with parallel operations,
typically yields the fastest way to bulk load data into your database.
•
A data load strategy involving external tables on
DBFS
, they can participate in the same RMAN backup strategy and
deployment as the rest of your database files.
•
When you store files in
DBFS
file systems can reside in ASM disks, so you can get the performance and availability
features of ASM within your
DBFS
file system.
•
DBFS
file systems can be mounted using a number of performance, security, and storage
features including compression, de-duplication, encryption, and partitioning. The encryption
configuration on
DBFS
provides the framework for Oracle Secure Files.
•
■
to learn more about oracle
DBFS
file system mount options, please consult the oracle 11gr2 secure Files and
large objects production documentation at
http://docs.oracle.com/cd/E14072_01/appdev.112/e10645/adlob_client.htm
.
to learn more about oracle secure Files and
DBFS
, please refer to
http://www.oracle.com/technetwork/database/
Note
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