Chapter 8. Managing Large Objects

Oracle8 and PL/SQL8 support the storage and manipulation of large objects (a.k.a. LOBs). A LOB, which can be a column in a table or an attribute of an object type, may store up to four gigabytes of data, such as character text, graphic images, video, or “raw” data. The DBMS_LOB package (new to Oracle8) provides a set of procedures and functions to access and manipulate LOBs from within PL/SQL programs.

You can also manipulate LOBs from within SQL; refer to the Oracle documentation for these SQL-specific aspects of LOB management.

Getting Started with DBMS_LOB

The DBMS_LOB package is created when the Oracle8 database is installed. The dbmslob.sql script (found in the built-in packages source directory, as described in Chapter 1) contains the source code for this package’s specification. This script is called by catproc.sql, which is normally run immediately after database creation. The script creates the public synonym DBMS_LOB for the package and grants EXECUTE privilege on the package to public. All Oracle users can reference and make use of this package.

DBMS_LOB Programs

Table 8.1 summarizes the programs available in DBMS_LOB.

Table 8-1. DBMS_LOB Programs

Name

Description

Use in SQL

APPEND

Appends the contents of a source internal LOB to a destination internal LOB

No

COMPARE

Compares two LOBs of the same type; parts of LOBs can also be compared

Yes

COPY

Copies all or part of the contents of a source internal LOB to a destination ...

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