Glossary
BFILE
A Large Object datatype that is a binary file residing in the file system, outside of the database data files and tablespace. Note that the BFILE
datatype is also referred to as an external LOB in some documentation.
Binary Large Object (BLOB)
A Large Object datatype that has content consisting of binary data and is typically used to hold unstructured data. The BLOB
datatype is included in the category Persistent LOBs because it resides in the database.
Character Large Object (CLOB)
The LOB data type that has content consisting of character data in the database character set. A CLOB can be indexed and searched by the Oracle Text search engine.
data interface
Data interface is a generic term referring to whichever interface is in use, to query the database or to update the database.
deduplication
Deduplication enables Oracle Database to automatically detect duplicate LOB data and conserve space by only storing one copy (if storage parameter is SECUREFILE
).
DBFS
The Database Filesystem, which is visible to end-users as the client-side API (dbms_dbfs_content
).
DBFS Link
Database File System Links (DBFS Links) are references from SecureFiles LOBs to data stored outside the segment where the SecureFiles LOB resides.
external LOB
A Large Object datatype that is stored outside of the database tablespace. The BFILE
datatype is the only external LOB datatype. See also BFILE
.
internal persistent LOB
A large object (LOB) that is stored in the database in a BLOB
/CLOB
/NCLOB
column.
Large Objects (LOBs)
Large Objects include the following SQL datatypes: BLOB
, CLOB
, NCLOB
, and BFILE
. These datatypes are designed for storing data that is large in size. See also BFILE
, Binary Large Object, Character Large Object, and National Character Large Object.
LOB attribute
A large object datatype that is a field of an object datatype. For example a CLOB
field of an object type.
LOB value
The actual data stored by the Large Object. For example, if a BLOB
stores a picture, then the value of the BLOB
is the data that makes up the image.
mount point
The path where the Database File System is mounted. Note that all file systems owned by the database user are seen at the mount point.
National Character Large Object
The LOB data type that has content consisting of Unicode character data in the database national character set. An NCLOB
can be indexed and searched by the Oracle Text search engine.
persistent LOB
A BLOB
, CLOB
, or NCLOB
that is stored in the database. A persistent LOB instance can be selected out of a table and used within the scope of your application. The ACID (atomic, consistent, isolated, durable) properties of the instance are maintained just as for any other column type. Persistent LOBs are sometimes also referred to as internal persistent LOBs or just, internal LOBs.
A persistent LOB can exist as a field of an object data type and an instance in a LOB-type column. For example a CLOB
attribute of an instance of type object
.
See also temporary LOB and external LOB.
SECUREFILE
LOB storage parameter that allows deduplication, encryption, and compression. The opposite parameter, that does not allow these features, is BASICFILE
.
SPI
The DBFS Store Provider Interface, visible to end-users as the server-side SPI (dbms_dbfs_content_spi
).
Store
A unified content repository, visible to the DBFS, and managed by a single store provider. The store itself may be a single relational table, a collection of tables, or even a collection of relational and non-relational entities (e.g., hierarchical stores like tapes and the cloud, elements inside an XML file, components of HDF-style documents, and so on.