The binary large object (
BLOB) data type is used to store large amounts of binary objects in a database. You can regard
BLOB objects as bitstreams that do not have character set semantics. A
BLOB object has a maximum length of 48 MB and uses the
BINARY character set.
BLOB objects have full transaction support. The changes that you make by using
SQL statements or the
DBMS_LOB package participate fully in the transaction. You can submit and roll back operations on
BLOB values. However, you cannot save a
BLOB locator in PL/SQL in one transaction and then use it in another transaction or session.
If you store an oversized binary file, the database performance is degraded.
In most cases, the
BLOB fields are used to store the information about large files in a database, such as images, files, and music files. The database converts large files to binary files and then stores the binary files.
In the following example, a table named blob_table is created, and the
BLOB data type is specified for the blob_cl column.
CREATE TABLE blob_table (blob_cl BLOB);