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In order to answer this question, I think it might be
best to clarify some terminology. Oracle introduced
Large Objects (LOBs) back in Oracle 8. The collection
of LOB datatypes are meant to replace the LONG and
LONG RAW datatypes available in earlier Oracle
versions.
For storing large character data, Oracle has the
Character LOB, or CLOB. This replaces the LONG
datatype. For storing binary large objects directly in
the database, use the Binary LOB datatype, or BLOB.
This replaces the LONG RAW datatype.
Additionally, one can reference binary objects from
the table, but the object does not even exist in the
database. This is done with the BFILE datatype. The
BFILE datatype is nothing more than a pointer to a
Binary File located on your database server's
filesystem.
Hopefully, you can see that there is a difference
between a "BLOB" and a "BFILE". A BLOB is stored
internally, and a BFILE is stored externally. A BLOB
gets the benefits of any internal datatype. A BFILE
must be managed by the OS. The OS is responsible for
the security of the object, backing up the object, and
handling the object. The database does all of this for
the BLOB.
Since a BFILE is stored externally, the database can
only read the binary object. It cannot write to the
BFILE. The only way to modify the BFILE object is to
use external programs, utilities, or OS commands to
modify the contents of the file itself. For many
applications, the easiest way to accomplish this is to
just erase the file and put a new file in it's place.
The database does not need to be updated since it just
has a pointer to the BFILE.
Oracle has supplied a PL/SQL package, DBMS_LOB, to
manipulate CLOBs and BLOBs right from your PL/SQL
routines, i.e. packages, procedures, triggers,
functions. If you do not like using the DBMS_LOB
package for your LOB manipulation, then many
application interfaces support LOB manipulation. For
instance, if you are coding in Java, then the JDBC
libraries contain functions for LOB manipulation.
Other application programming interfaces have similar
routines and you may want to check them out!
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